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Common Barn Owl - Tyto alba
Common Barn Owl - Tyto alba

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Scientific classification 
Kingdom: Animalia 
Phylum: Chordata 
Class: Aves 
Subclass: Neornithes 
Infraclass: Neognathae 
Superorder: Neoaves 
Order: Strigiformes 
Family: Tytonidae 
Subfamily: Tytoninae 
Genus: Tyto 
Species: Tyto alba

These pale, nearly worldwide, birds are closely associated with man through their traditional use in the Old World of barn lofts and church steeples as nesting sites. Although widely known beforehand, it was in 1769 when the Barn Owl was first officially described by Giovanni Scopoli, an Italian naturalist. The species name "alba" also refers to the colour white. Other names for the Barn Owl have included Monkey-faced Owl, Ghost Owl, Church Owl, Death Owl, Hissing Owl, Hobgoblin or Hobby Owl, Golden Owl, Silver Owl, White Owl, Night Owl, Rat Owl, Scritch Owl, Screech Owl, Straw Owl, Barnyard Owl and Delicate Owl.

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The Upperparts are light grey with numerous fine dark lines and scattered pale spots on the feathers. There are buff markings on wings and on the back. The underparts are white with a few black spots, occasionally none. Feathering on the lower legs may be sparse. The heart-shaped facial disc is white with a brownish edge, with brown marks at the front of the eyes, which have a black iris. Its beak is off-white and the feet are yellowish-white to brownish. Males and females are similar in size and colour, females and juveniles are generally more densely spotted.

Female: Length 34-40cm (13.5-15.5") Wingspan 110cm (43") Weight 570g (20oz)
Male: Length 32-38cm (12.5-15") Wingspan 107cm (42") Weight 470g (15.5oz)

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The Barn Owl is one of the most wide-spread of all land birds. They are found on all continents (except Antarctica) and large islands and occur over the whole of Australia, including Tasmania. They occur throughout most of Britain and Europe and across many parts of Asia, Africa, and in much of North America. In South America they are found in areas of suitable grassland, as well as on oceanic islands such as the Galapagos. They were introduced to Hawaii in 1958.

The Barn Owl is found in virtually all habitats but much more abundantly in open woodland, heaths and moors than forested country. They usually roost by day in tree hollows but have also been found in caves, wells, out-buildings or thick foliage. 

Generally nocturnal, although it is not uncommon to see this species emerge at dusk or be active at dawn, occasionally being seen in flight during full daylight. Flight is noiseless, with wingbeats interrupted by gliding. 

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The Barn Owl calls infrequently, the usual call being a drawn-out rasping screech. The courtship call of male at nest is a shrill repetitive twittering. Adults returning to a nest may give a low, frog-like croak. When surprised in its roosting hollow or nest, it makes hissing and rasping noises and snapping sounds that are often called bill snapping, but possibly made by clicking the tongue. 

Hunting & Food: 
Barn Owls specialise in hunting small ground mammals, and the vast majority of their food consists of small rodents. Voles (field mice) are an important food item, as well as pocket gophers, shrews, mice and rats. Barn Owls breed rapidly in response to mouse plagues. Other prey may include baby rabbits, bats, frogs, lizards, birds and insects. Prey are usually located by quartering up and down likely looking land - particularly open grassland. They also use low perches such as fence posts to seek quarry.

Barn Owls will breed any time during the year, depending on food supply. In a good year, a pair may breed twice. Rodent plagues cause Barn Owl numbers to increase dramatically. During courting, males may circle near the nest tree, giving short screeches and chattering calls. The majority of Barn Owls nest in tree hollows up to 20 metres high. They will also nest in old buildings, caves and well shafts. 3 to 6 eggs are laid (occasionally up to 12) at 2 day intervals. The eggs are 38 to 46mm (1.5-1.8") long and 30 to 35mm (1.2-1.4") wide and will be incubated for 30 to 34 days. Chicks are covered in white down and brooded for about 2 weeks, and are fledged in 50 to 55 days. After this, they will remain in the vicinity for a week or so to learn hunting skills and then rapidly disperse from the nest area. Young birds are able to breed at about 10 months.

Barn Owls are short-lived birds. Most die in their first year of life, with the average life expectancy being 1 to 2 years in the wild. In North America the oldest known Barn Owl in the wild lived to be 11 years, 6 months. In Holland, a wild barn owl lived to be 17 years, 10 months old.
In England, a captive female barn owl was retired from breeding at 25 years old!
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  • Claudiu Constantin Nicolaescu
Hearing Skills Of Barn Owls Could Map Way To Find Problems In Humans

Science Daily — The hearing precision that lets common barn owls find prey is helping researchers fine tune their quest to diagnose a variety of problems rooted in the human brain, not only with hearing but also with behavior and potentially damaged areas.

University of Oregon researchers have found that barn owls (Tyto alba) are better able to track changes in the location of a noise, such as that made by a potential meal, when the sound source moves horizontally than when the sound changes direction vertically. The discovery was made using an infrared-monitoring procedure that measures pupil dilation responses that are influenced by changes in sound sources around an owl.

"When we are looking at problems of spatial localization, or how to locate sound in a space, the barn owl provides a great system," said Avinash D.S. Bala, a researcher in the University of Oregon's Institute of Neuroscience and lead author of a new study.

The findings -- published in Aug. 1 issue of PLoS One-- confirms and solidifies the results of an earlier study (Nature, Aug. 14, 2003), in which Bala and colleagues first documented the brain mapping of firing neurons to horizontal changes in the source of noises in the owl's brain.

Bala was the lead author on both projects, which were done in collaboration with former UO researcher Matthew W. Spitzer, who now is at Monash University in Australia, and principal investigator Terry T. Takahashi, a UO professor of biology and researcher in the Institute of Neuroscience.

"The barn owl has a portion of the midbrain which serves as a map," Bala said. "Neuron activity can be traced in the map as sound moves. Looking at this map, you can decipher which sounds are being received more actively."

The new study, in which conclusions were based on the recordings of 62 neurons that represent auditory space, also sheds light on how outside information is converted into electrical activity and transformed into behavior.

"The brain, in the case of spatial hearing, judges neuronal activity in a democratic manner," Bala said. "It listens to the responses of neurons, and it goes with an approximate average of responses. This has the advantage of reducing environmental noise that is inducing false positives, which would be more common if the owl was depending on only a few neurons. Overall sensitivity might go down, but the probability of an owl actually hitting its prey becomes much higher."

The monitoring procedure Bala and colleagues have devised, which is in the early stages of human application, has the potential to use the eyes, through changes in the size of the pupil, as a gateway to the human brain. The system would allow for measuring the response to different aspects of sound, such as volume, pitch and location, as well as diagnosing basic sensory deficits and identify areas of damage in the brain.

The National Institute of Deafness and Communication Disorders and the McKnight Foundation, a private Minnesota-based philanthropic organization, funded the work through grants to Takahashi. Spitzer was supported by a grant from the National Institutes of Health.
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  • Claudiu Constantin Nicolaescu
For Owls, Gals with Big Spots Drive the Guys Wild

By Clara Moskowitz, LiveScience Senior Writer
posted: 19 November 2010 04:31 pm ET

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Female barn owls with larger spots on their coats get more mates, a study finds. 

"What nice spots you have" could apparently be a barn owl pickup line. A new study found that female barn owls with larger spots seem to up their sexy quotient, and have greater success in mating.

Perplexingly, the same trait — large dark spots on the tips of the white feathers covering the owl's body — appears to hurt male barn owls' reproductive success. 

In the new study, researchers followed barn owls over several molting periods and measured any changes in their successive coats. They found that adult females bred earlier in the season and laid larger eggs when their new coats became scattered with larger spots. In contrast, males with this trait fared less well.

"The key story is that there is sexually antagonistic selection — females are selected in one direction, and males in another direction," said Alexandre Roulin of the University of Lausanne in Switzerland, co-author of the new study. An example of sexually antagonistic selection in humans, he said, is the hip bone. In females, larger hips are selected for because they aid in childbirth, while in males, larger hips are selected against because they hinder the ability to run fast.

However, for owls, it's less clear what adaptive function dark spots would have.

Whatever the reason, on female owls, larger spots definitely attract the boys. In a related study, the researchers found that when male barn owls were mated with females whose spots had been removed, they reduced their sperm investment, and chicks from such pairings didn't fare as well. 

But why are spots so attractive on a female?

"My guess is that the size of the spots signals gene quality," Roulin told LiveScience.

The dark coloring of the spots is caused by the pigment melanin. Whatever gene or genes in barn owls that are responsible for the production of melanin may have other biological functions that are somehow beneficial in females, Roulin said. And this same gene may be somehow harmful in males.

But it's too early to know which genes may be involved, and to figure out why they have these puzzling effects.

"Now we would like to understand why we find this result, because it seems very strange — females with spots do better and males do less well," Roulin said. "My impression is we came to a system where there are really great things to discover."

Roulin and Lausanne colleague Amelie Dreiss reported their findings in the November 2010 issue of the Biological Journal of the Linnean Society.
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  • Claudiu Constantin Nicolaescu
Barn owl wings adapted for silent flight

By Victoria Gill Science reporter, BBC Nature
19 January 2012

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The curvature of barn owls' wings helps them fly slowly and silently

Their screech is one of nature's eeriest sounds, but barn owls hunt in almost total silence.

Now researchers in Germany have revealed how the predators' wings are specially adapted to allow noiseless flight.

Their supreme stealth is thanks, largely, to their ability to fly so slowly - with relatively little beating of their wings.

And the shape and size of the owls' wings enables this very slow flight.

Dr Thomas Bachmann from the Technical University Darmstadt in Germany recently presented his study of barn owl wings at the Society for Integrative and Comparitive Biology's annual meeting in Charleston, South Carolina.

Quote:[Image: _57929035_barn_owl_lm_stone_npl.jpg]
Barn owl
  • Barn owls can locate their prey in total darkness, using only their hearing
  • The owls' heart-shaped face works in a similar way to humans' outer ears - collecting and directing sound toward the inner ears
  • Each of a barn owls' two ears is a slightly different size and shape, and one is higher on the bird's head than the other. The owls can analyse the differences in the sound received by each ear to automatically calculate the exact position of that sound-source

He explained to BBC Nature that barn owls were highly specialised nocturnal hunters.

"They hunt mainly in the dark, so visual information is very limited.

"They use acoustic information to locate their prey."

Their silent flight helps them listen for the scurrying of the voles they hunt for, and also reduces their chances of being heard by the prey as they approach.

To find out how they managed to fly so slowly and quietly, Dr Bachmann examined the birds' wings in minute detail.

He examined the plumage and took 3-D medical scans of their skeletal structure.

The wings' most important features, he explained, were the high curvature or "camber" of the wings. This curvature means that each wing beat produces more lift.

This is because, Dr Bachmann explained, the air flow is accelerated over the upper surface the curved wing. "So the pressure drops," he said. "[And] the wing is sucked upwards into the lower pressure on the upper wing surface."

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The fine feathery fringes of each wing also help silence the owl's flight

The feathery edges of each wing are also extremely fine - reducing any loud turbulence during flight, explained Dr Bachmann.

"Friction noise between single feathers is also reduced [by] their velvety surface," he told BBC Nature.

In fact, Dr Bachmann explained, "all the body parts of the owl are covered by very dense plumage - owls have more feathers than other similarly sized birds".

This soft, dense plumage absorbs other sounds the birds make as they fly.

Dr Bachmann and his team say their eventual aim is to use the structure of barn owl wings to inform the design of new, much quieter airfoils for the aviation industry.

"We're trying to understand the basic principles... that influence the airflow over aircraft and thus reduce noise," he explained.

"[But] we are far away from that point. Maybe in 20 years we can present such a wing.

"Until then, we will conduct many more experiments on owl wings."

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The structure of barn owls' wings could provide a guide for the design of quieter and more efficient airfoils
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  • Claudiu Constantin Nicolaescu
Baby Owls Sleep Like Baby Humans: Owlets Spend More Time in REM Sleep Than Adult Owls

Aug. 2, 2013 — Baby birds have sleep patterns similar to baby mammals, and their sleep changes in the same way when growing up. This is what a team from the Max Planck Institute for Ornithology and the University of Lausanne found out working with barn owls in the wild. The team also discovered that this change in sleep was strongly correlated with the expression of a gene involved in producing dark, melanic feather spots, a trait known to covary with behavioral and physiological traits in adult owls. These findings raise the intriguing possibility that sleep-related developmental processes in the brain contribute to the link between melanism and other traits observed in adult barn owls and other animals.
Sleep in mammals and birds consists of two phases, REM sleep ("Rapid Eye Movement Sleep") and non-REM sleep. We experience our most vivid dreams during REM sleep, a paradoxical state characterized by awake-like brain activity. Despite extensive research, REM sleep's purpose remains a mystery. One of the most salient features of REM sleep is its preponderance early in life. A variety of mammals spend far more time in REM sleep during early life than when they are adults. For example, as newborns, half of our time asleep is spent in REM sleep, whereas last night REM sleep probably encompassed only 20-25% percent of your time snoozing.
Although birds are the only non-mammalian group known to clearly engage in REM sleep, it has been unclear whether sleep develops in the same manner in baby birds. Consequently, Niels Rattenborg of the MPIO, Alexandre Roulin of Unil, and their PhD student Madeleine Scriba, reexamined this question in a population of wild barn owls. They used an electroencephalogram (EEG) and movement data logger in conjunction with minimally invasive EEG sensors designed for use in humans, to record sleep in 66 owlets of varying age. During the recordings, the owlets remained in their nest box and were fed normally by their parents. After having their sleep patterns recorded for up to five days, the logger was removed. All of the owlets subsequently fledged and returned at normal rates to breed in the following year, indicating that there were no long-term adverse effects of eves-dropping on their sleeping brains.
Despite lacking significant eye movements (a trait common to owls), the owlets spent large amounts of time in REM sleep. "During this sleep phase, the owlets' EEG showed awake-like activity, their eyes remained closed, and their heads nodded slowly," reports Madeleine Scriba from the University of Lausanne (see video in the link below). Importantly, the researchers discovered that just as in baby humans, the time spent in REM sleep declined as the owlets aged.
In addition, the team examined the relationship between sleep and the expression of a gene in the feather follicles involved in producing dark, melanic feather spots. "As in several other avian and mammalian species, we have found that melanic spotting in owls covaries with a variety of behavioral and physiological traits, many of which also have links to sleep, such as immune system function and energy regulation," notes Alexander Roulin from the University of Lausanne. Indeed, the team found that owlets expressing higher levels of the gene involved in melanism had less REM sleep than expected for their age, suggesting that their brains were developing faster than in owlets expressing lower levels of this gene. In line with this interpretation, the enzyme encoded by this gene also plays a role in producing hormones (thyroid and insulin) involved in brain development.
Although additional research is needed to determine exactly how sleep, brain development, and pigmentation are interrelated, these findings nonetheless raise several intriguing questions. Does variation in sleep during brain development influence adult brain organization? If so, does this contribute to the link between behavioral and physiological traits and melanism observed in adult owls? Do sleep and pigmentation covary in adult owls, and if so how does this influence their behavior and physiology? Finally, Niels Rattenborg from the Max Planck Institute for Ornithology in Seewiesen hopes that "this naturally occurring variation in REM sleep during a period of brain development can be used to reveal exactly what REM sleep does for the developing brain in baby owls, as well as humans."

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As they get older, baby owls change their sleeping patterns. The older they get, the less time they spent in REM sleep.

Journal Reference:
Madeleine F Scriba, Anne-Lyse Ducrest, Isabelle Henry, Alexei L Vyssotski, Niels C Rattenborg, Alexandre Roulin. Linking melanism to brain development: expression of a melanism-related gene in barn owl feather follicles covaries with sleep ontogeny. Frontiers in Zoology, 2013; 10 (1): 42 DOI: 10.1186/1742-9994-10-42

Intra-specific variation in melanocyte pigmentation, common in the animal kingdom, has caught the eye of naturalists and biologists for centuries. In vertebrates, dark, eumelanin pigmentation is often genetically determined and associated with various behavioral and physiological traits, suggesting that the genes involved in melanism have far reaching pleiotropic effects. The mechanisms linking these traits remain poorly understood, and the potential involvement of developmental processes occurring in the brain early in life has not been investigated. We examined the ontogeny of rapid eye movement (REM) sleep, a state involved in brain development, in a wild population of barn owls (Tyto alba) exhibiting inter-individual variation in melanism and covarying traits. In addition to sleep, we measured melanistic feather spots and the expression in the feather follicles of a gene implicated in melanism (PCSK2).
As in mammals, REM sleep declined with age across a period of brain development in owlets. In addition, inter-individual variation in REM sleep around this developmental trajectory was predicted by variation in PCSK2 expression in the feather follicles, with individuals expressing higher levels exhibiting a more precocial pattern characterized by less REM sleep. Finally, PCSK2 expression was positively correlated with feather spotting.
We demonstrate that the pace developmental processes occurring in the brain, as reflected in age-related changes in REM sleep, covary with the peripheral activation of the melanocortin system. Given its role in brain development, variation in nestling REM sleep may lead to variation in adult brain organization, and thereby contribute to the behavioral and physiological differences observed between adults expressing different degrees of melanism.
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  • Claudiu Constantin Nicolaescu
Barn owl nestlings recognise their siblings' calls

25 November 2013 Last updated at 09:24 Share this pageEmailPrint

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Barn owl nestlings

Barn owl nestlings recognise their siblings' calls, according to researchers.

Instead of competing aggressively for food, young barn owls are known to negotiate by calling out.

A team of scientists in Switzerland discovered that the owlets have remarkably individual calls.

They suggest this is to communicate each bird's needs and identity in the nest.

The findings were announced in the Journal of Evolutionary Biology by Dr Amelie Dreiss and colleagues at the University of Lausanne, Switzerland.

Barn owls (Tyto alba) are considered one of the most widespread species of bird and are found on every continent except Antarctica.

An average clutch size ranges between four and six eggs but some have been known to contain up to 12.

Previous studies have highlighted how barn owl nestlings, known as owlets, negotiate with their siblings for food instead of fighting.

While their parents search for food the owlets advertise their hunger to their brothers and sisters by calling out.

"These vocal signals deter siblings from vocalizing and from competing for the prey at parental return," explained Dr Dreiss.

"If there is a disagreement, they can escalate signal intensity little by little, always without physical aggression, until less hungry siblings finally withdraw from the contest."

To understand more about about this communication, researchers studied wild owls living in nest boxes in western Switzerland.

Based on recordings, the scientists estimated that a single nestling makes up to 5,000 calls a night in the absence of its parents.

They suggested that the probability of the chick making false signals is low because it is an energetically costly activity.

Earlier this year another member of the research team, Prof Alexandre Roulin, revealed that the owlets do not interrupt each other's calls and that they eavesdrop on calling contests as part of this negotiation for food.

In their latest study, Dr Dreiss and colleagues recruited students to listen to the recorded calls of owl chicks.

The students were able to tell the difference between owlets' calls by ear, suggesting that the birds had individual voices that made them identifiable to nest mates.

Further analysis of the calls revealed that they varied depending on the owlet's family, age and sex, as well as how hungry they were.

Dr Dreiss suggests this shows that sibling rivalry has promoted the evolution of individual voices amongst barn owls.

Individual vocal signatures in barn owl nestlings: does individual recognition have an adaptive role in sibling vocal competition?

A. N. Dreiss*, C. A. Ruppli, A. Roulin
Article first published online: 8 NOV 2013

DOI: 10.1111/jeb.12277

© 2013 The Authors. Journal of Evolutionary Biology © 2013 European Society For Evolutionary Biology
Issue Cover image for Vol. 26 Issue 12
Journal of Evolutionary Biology

To compete over limited parental resources, young animals communicate with their parents and siblings by producing honest vocal signals of need. Components of begging calls that are sensitive to food deprivation may honestly signal need, whereas other components may be associated with individual-specific attributes that do not change with time such as identity, sex, absolute age and hierarchy. In a sib–sib communication system where barn owl (Tyto alba) nestlings vocally negotiate priority access to food resources, we show that calls have individual signatures that are used by nestlings to recognize which siblings are motivated to compete, even if most vocalization features vary with hunger level. Nestlings were more identifiable when food-deprived than food-satiated, suggesting that vocal identity is emphasized when the benefit of winning a vocal contest is higher. In broods where siblings interact iteratively, we speculate that individual-specific signature permits siblings to verify that the most vocal individual in the absence of parents is the one that indeed perceived the food brought by parents. Individual recognition may also allow nestlings to associate identity with individual-specific characteristics such as position in the within-brood dominance hierarchy. Calls indeed revealed age hierarchy and to a lower extent sex and absolute age. Using a cross-fostering experimental design, we show that most acoustic features were related to the nest of origin (but not the nest of rearing), suggesting a genetic or an early developmental effect on the ontogeny of vocal signatures. To conclude, our study suggests that sibling competition has promoted the evolution of vocal behaviours that signal not only hunger level but also intrinsic individual characteristics such as identity, family, sex and age.
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Ceratodromeus Wrote:Barn Owl (Tyto alba) predation on Corallus hortulanus (Squamata, Boidae) (Henderson & Silva 2013)
Quote:Species of the Neotropical treeboa genus Corallus occur from Guatemala to southern Brazil and on continental and oceanic islands. They often are conspicuous members of their respective herpetofaunas. Despite this, we have few direct observations of treeboas capturing prey (Henderson, 2002; da Costa Silva et al., 2012) and even fewer observations of predation on treeboas (Henderson, 2002). The only record of predation on the geographically widespread Corallus hortulanus (Linnaeus) was by a Smooth-fronted Caiman (Paleosuchus trigonatus) in Amazonian Peru (W.W. Lamar in Henderson, 2002). Here we report predation on C. hortulanus by the geographically widespread Barn Owl (Tyto alba) along Igarapé do Galego, a small stream that lows through rice plantations and that is inundated during high tides. It is located on Ilha das Canárias, situated in the extreme eastern portion of Maranhão state, Brazil, and represents a large portion of the Parnaíba Delta (with an area of 115 km2). On the night of 14 July 2012 at 2030 h during a survey for Corallus hortulanus, one of us (PdCS) observed an adult C. hortulanus with a total length of about 1.0 m about 30 cm above ground level in a rice (Oryza) plantation and with its head moving and angled upward while licking its tongue. Also observed was an adult Barn Owl sitting on a dried branch of a Red Mangrove (Rhizophora mangle) about 2.6 m above ground level and about 6.0 m from the C. hortulanus. The owl appeared to be scanning its surroundings, presumably searching for food. At 2032 h the owl’s head was angled downward and toward the boa. At 2035 h the boa stopped moving and remained motionless while the Barn Owl continued to orient its head in the direction of the snake. At 2045 h the owl lew from the mangrove, attacked and grasped the boa at its neck, and lew off with the boa in its talons. Although Henderson (2002) suggested that raptors are the most important predators on species of Corallus, little documentation supports that assumption. Aside from the observation reported herein, Bierregaard (1984) noted predation on C. caninus by a Guiana Crested Eagle (Morphnus guianensis) in Amazonian Brazil. Nevertheless, we still are inclined to believe that raptors are the most important predators of arboreal boids in the genus Corallus.
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Barn owls threatened by Africanized bees in South Florida

Date: June 19, 2015
Source: University of Florida Institute of Food and Agricultural Sciences
Throughout the past two decades, researchers have seen barn owl populations in the Everglades Agricultural Area, centered around Belle Glade, expand from mere dozens to more than 400 nesting pairs. But these beneficial raptors, currently listed as a threatened species, are now being threatened by Africanized honey bees.

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UF/IFAS researcher Richard Raid and a barn owl in Belle Glade, Fla.

Throughout the past two decades, University of Florida researcher Richard Raid has seen barn owl populations in the Everglades Agricultural Area, centered around Belle Glade, expand from mere dozens to more than 400 nesting pairs.

But these beneficial raptors, currently listed as a threatened species, are now being threatened by Africanized honey bees. Swarming as frequently as eight times per year, the invasive bees have been taking over nesting boxes Raid and students have built for the owls, using them as hives, and displacing or even killing the desired raptors.

"In 20 years, we've never had any problems with any other critters moving into our boxes," said Raid, a plant pathologist for UF's Institute of Food and Agricultural Sciences. "But the Africanized honey bees became established in 2005 and are spreading throughout the peninsula of Florida."

These Africanized bee swarms also pose a very real threat to agricultural workers, who may unwittingly disturb their sometimes hidden colonies.

And so Raid is working with UF entomologist William Kern and graduate student Caroline Efstathion, both from the Ft. Lauderdale Research and Education Center, to build new, attractive homes for the bees -- accepting the fact that they are here to stay. The researchers have devised a "push-pull" integrated pest management strategy for dealing with the Africanized honey bee feral swarms. They spray the owl nest boxes with an insecticide that is virtually non-toxic to the owls but is repellent to the bees, pushing them out of the boxes. Additionally, they pull the bees into nearby "swarm traps," using a synthetic pheromone that honey bee workers use to mark the new hives.

Evolving out of a high school science fair project conducted some 20 years ago, the UF Barn Owl Project promotes the placement of nesting boxes on farms as a way to enhance barn owl populations.

"These birds provide environmentally friendly, low‐cost, sustainable rodent control," Raid explained. "The pests, particularly cotton rats, mice, and marsh rabbits, can cause over $30 million in damage each year to the area's 700,000 acres of sugar cane, rice and vegetable crops."

Thus far, it appears the research efforts are working. Nesting box colonization by the bees has dropped dramatically, while nearly 70 Africanized honey bee swarms have been captured. Raid points out that failing to manage these invasive hybrid honey bees could have endangered this ongoing rodent IPM program.

Story Source: University of Florida Institute of Food and Agricultural Sciences. "Barn owls threatened by Africanized bees in South Florida." ScienceDaily. (accessed June 19, 2015). 
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  • Claudiu Constantin Nicolaescu
The owls beyond the Andes: Divergence between distant populations suggests new species

Date: November 11, 2015
SourceTongueensoft Publishers
They might be looking quite identical, but each of the populations of two owl species, living in the opposite hemispheres, might actually turn out to be yet another kind. This suggestion has been made by Dr. Colihueque and his team, based on new genetic divergence analyses of the Common Barn and the Short-eared Owl populations from Chile and comparing them with those from other geographic areas. The study is published in the open-access journal ZooKeys.

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This is a short-eared owl in Chile.
Credit: Dr. Nelson Colihueque; CC-BY 4.0

They might be looking quite identical, while perched above humanised farmlands and grasslands across several continents, but each of the populations of two owl species, living in the opposite hemispheres, might actually turn out to be yet another kind. This suggestion has been made by Dr. Nelson Colihueque and his team from Universidad de Los Lagos, Chile, based on new genetic divergence analyses of the Common Barn and the Short-eared Owl populations from southern Chile and comparing them with those from other geographic areas. The study is published in the open-access journal ZooKeys.

Although much has been known about the two widespread owl species, the knowledge about them has so far been restricted mainly to aspects such as their diet, conservation status and habitats. On the other hand, their genetic divergence in comparison with populations in distant areas has received little attention. Moreover, their taxonomical status is still based on traditional identification rather than modern methods such as the herein utilised mitochondrial COI sequencing.

Thus, the Chilean research team concluded a significant genetic divergence among the populations of both species from a few distinctive groups. In the case of the Common Barn Owl they compared the new analysis of its South American representatives with already available such data about populations from North America, Northern Europe and Australasia. For the Short-eared Owl, they compared Chilean and Argentinean birds with North American and North Asian.

One of the reasons behind such an evolutionary divergence might be the geographic isolation, experienced by the peripheral South American populations of both owl species. It is a consequence of the Andean Mountains acting as a natural barrier.

"In the case of the Common Barn Owl, the existence of geographic barriers to gene flow among populations on different continents is to be expected, and this in combination with its non-migratory or short-distance migratory behaviour, should contribute to promote the genetic divergence," further explain the authors.

In conclusion, the researchers call for additional studies to clarify the taxonomic identification of these owl populations.

Story Source:
Pensoft Publishers. "The owls beyond the Andes: Divergence between distant populations suggests new species." ScienceDaily. (accessed November 12, 2015).

Journal Reference:
Nelson Colihueque, Alberto Gantz, Jaime Rau, Margarita Parraguez. Genetic divergence analysis of the Common Barn Owl Tyto alba (Scopoli, 1769) and the Short-eared Owl Asio flammeus (Pontoppidan, 1763) from southern Chile using COI sequence. ZooKeys, 2015; 534: 135 DOI: 10.3897/zookeys.534.5953

In this paper new mitochondrial COI sequences of Common Barn Owl Tyto alba (Scopoli, 1769) and Short-eared Owl Asio flammeus (Pontoppidan, 1763) from southern Chile are reported and compared with sequences from other parts of the World. The intraspecific genetic divergence (mean p-distance) was 4.6 to 5.5% for the Common Barn Owl in comparison with specimens from northern Europe and Australasia and 3.1% for the Short-eared Owl with respect to samples from north America, northern Europe and northern Asia. Phylogenetic analyses revealed three distinctive groups for the Common Barn Owl: (i) South America (Chile and Argentina) plus Central and North America, (ii) northern Europe and (iii) Australasia, and two distinctive groups for the Short-eared Owl: (i) South America (Chile and Argentina) and (ii) north America plus northern Europe and northern Asia. The level of genetic divergence observed in both species exceeds the upper limit of intraspecific comparisons reported previously for Strigiformes. Therefore, this suggests that further research is needed to assess the taxonomic status, particularly for the Chilean populations that, to date, have been identified as belonging to these species through traditional taxonomy. 
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  • Claudiu Constantin Nicolaescu
Owls hold secret to ageless ears

By Helen Briggs
BBC News
3 hours ago

[Image: _97869325_gettyimages-497741484.jpg]
Barn owls rely on their hearing to hunt

Barn owls keep their acute sense of hearing into old age, scientists have discovered.
Previously, starlings have been found to have this ability, suggesting birds are protected from age-related hearing loss.
Understanding more about the "ageless ears" of barn owls could help develop new treatments for human hearing problems.
Birds are able to naturally repair damage to the inner ear.
Georg Klump of the University of Oldenburg, Germany, a researcher on the study, said owls keep their hearing into very old age.
"Birds can repair their ears like (humans) can repair a wound," he said. "Humans cannot re-grow the sensory cells of the ears but birds can do this."
It appears that humans lost these regenerative abilities at some point in evolution. Like all mammals, people commonly suffer from hearing loss in old age.
By the age of 65, humans can expect to lose more than 30 dB in sensitivity at high frequencies.
Commenting on the study, Dr Stefan Heller of Stanford University School of Medicine, said work was underway to investigate differences between birds and mammals.
"To truly utilise this knowledge, we need to conduct comparative studies of birds and mammals that aim to find the differences in regenerative capacity, a topic that is actively pursued by a number of laboratories worldwide," he said.
The research, published in the journal, Royal Society Proceedings B, was carried out on seven captive barn owls.
The birds were trained to fly to a perch to receive a food reward in response to sounds.
Even the oldest owl, which reached the ripe old age of 23, showed no signs of age-related hearing loss.
Barn owls typically only live to the age of three or four in the wild. The birds rely on their hearing to hunt prey at night.

Journal Reference:
Bianca Krumm, Georg Klump, Christine Köppl, Ulrike Langemann Barn owls have ageless ears Published 20 September 2017.DOI: 10.1098/rspb.2017.1584

We measured the auditory sensitivity of the barn owl (Tyto alba), using a behavioural Go/NoGo paradigm in two different age groups, one younger than 2 years (n = 4) and another more than 13 years of age (n = 3). In addition, we obtained thresholds from one individual aged 23 years, three times during its lifetime. For computing audiograms, we presented test frequencies of between 0.5 and 12 kHz, covering the hearing range of the barn owl. Average thresholds in quiet were below 0 dB sound pressure level (SPL) for frequencies between 1 and 10 kHz. The lowest mean threshold was –12.6 dB SPL at 8 kHz. Thresholds were the highest at 12 kHz, with a mean of 31.7 dB SPL. Test frequency had a significant effect on auditory threshold but age group had no significant effect. There was no significant interaction between age group and test frequency. Repeated threshold estimates over 21 years from a single individual showed only a slight increase in thresholds. We discuss the auditory sensitivity of barn owls with respect to other species and suggest that birds, which generally show a remarkable capacity for regeneration of hair cells in the basilar papilla, are naturally protected from presbycusis. 
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Journal Reference:
Vera Uva, Martin Päckert, Alice Cibois, Luca Fumagalli and Alexandre Roulin. 2018. Comprehensive Molecular Phylogeny of Barn Owls and Relatives (Family: Tytonidae), and Their Six Major Pleistocene Radiations. Molecular Phylogenetics and Evolution. 125; 127-137. DOI: 10.1016/j.ympev.2018.03.013

[Image: Tytonidae_Phylogeny-2018_Uva_P%25C3%25A4..._et-al.jpg]

• Tytonidae originated in the Oligocene (ca. 28 mya) of Australasia.
• Tytonidae underwent six trans-continental radiations in the Pleistocene.
• Split of Tyto alba into three species (T. alba, T. furcata, T. javanica) is supported.
• T. rosenbergii and T. nigrobrunnea are subspecies of T. javanica; T. sororcula and T. manusi are subspecies of T. novaehollandiae.
• Grass owls and sooty owls are a single species each (T. capensis and T. tenebricosa).

The owl family Tytonidae comprises two genera: Phodilus, limited to the forests of central Africa and South-East Asia, and the ubiquitous Tyto. The genus Tyto is majorly represented by the cosmopolitan Common Barn Owl group, with more than 30 subspecies worldwide. Discrete differences in body size and plumage colouration have led to the classification of this family into many species and subspecies, but the taxonomic status and phylogenetic relationships between taxa remain unclear, and in some groups controversial. Although several previous studies attempted to resolve this problem, they have been limited in their taxonomic and geographical coverage, or have relied on restricted molecular evidence and low sample sizes. Based on the most comprehensive sampling to date (16 out of 17 Tyto species, and one out of three Phodilus species), a multi-locus approach using seven mitochondrial and two nuclear markers, and taking advantage of field data and museum collections available worldwide, our main questions in this study were: (1) what are the phylogenetic relationships and classification status of the whole family; (2) when and where did the most important speciation events occur? We confirm that the Common Barn Owl, Tyto alba is divided into three main evolutionary units: the American Barn Owl, T. furcata; the Western Barn Owl, T. alba; and the Eastern Barn Owl, T. javanica, and suggest a Late Miocene (ca. 6 mya) Australasian and African origin of the group. Our results are supported by fossil age information, given that the most recent common ancestor between the Tytonidae genera Phodilus and Tyto was probably from the Oligocene (ca. 28 mya) of Australasia. We finally reveal six major Pleistocene radiations of Tyto, all resulting in wide-range distributions.

[Image: Tytonidae_Phylogeny-2018_Vera_Martin_Alice_et-al_ii.jpg] 
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  • Claudiu Constantin Nicolaescu
Owls see as humans do
Humans and birds may be more similar than previously thought

Date: July 2, 2018
Source: Society for Neuroscience

[Image: 180702133858_1_900x600.jpg]
This montage illustrates a barn owl (Tyto alba) watching a monitor displaying a paradigm which tests behavioral and neural responses to figure-ground segregation. The paradigm consists of a target dot appearing inside the borders of the site's receptive field (figure, represented by the dashed red circle), and moving to the right (denoted by the gray arrow), surrounded by dots-array (ground). The colors of the arrows represent 3 types of movement tested: (1) magenta relates to condition where 100% of the circles moved 1350 upwards; (2) green relates to condition where 70% of the circles moved 1350 upwards; (3) blue relates to condition where 50% of the circles moved 1350 upwards. In behaving barn owls the coherency of the background motion modulates the perceived saliency of the target object, and in complementary multi-unit recordings in the Optic Tectum, the neural responses were more sensitive to the homogeneity of the background motion than to motion-direction contrasts between the receptive field and the surround.
Credit: Yoram Gutfreund

A study of barn owls published in JNeurosci suggests the visual systems of humans and birds may be more similar than previously thought.

The ability to perceive an object as distinct from a background is crucial for species that rely on vision to act on their environment. One way humans achieve this is by grouping different elements of a scene into "perceptual wholes" based on the similarity of their motion. This phenomenon has been mostly studied in primates, leaving open the question of whether such perceptual grouping represents a fundamental property of visual systems in general.

Yoram Gutfreund and colleagues addressed this question by studying the brain and behavior of barn owls as the animals tracked dark dots on a gray background presented on a computer screen. A wireless "Owl-Cam" tracked the owls' visual search behavior in one set of experiments while neural activity in the optic tectum -- the main visual processor in non-mammalian vertebrates -- was recorded in another.

The researchers indeed report evidence of perceptual grouping in the owl, suggesting that this ability evolved and was conserved across species prior to the development of the human neocortex.

Story Source: Society for Neuroscience. "Owls see as humans do: Humans and birds may be more similar than previously thought." ScienceDaily. (accessed July 2, 2018).

Journal Reference:
Zahar Yael, Tidhar Lev-Ari, Hermann Wagner, Yoram Gutfreund. Behavioral evidence and neural correlates of perceptual grouping by motion in the barn owl. The Journal of Neuroscience, 2018; 0174-18 DOI: 10.1523/JNEUROSCI.0174-18.2018

Perceiving an object as salient from its surround often requires a preceding process of grouping the object and background elements as perceptual wholes. In humans, motion homogeneity provides a strong cue for grouping, yet, it is unknown to what extent this occurs in non-primate species. To explore this question, we studied the effects of visual motion homogeneity in barn owls of both genders, at the behavioral as well as the neural level. Our data show that the coherency of the background motion modulates the perceived saliency of the target object. An object moving in an odd direction relative to other objects attracted more attention when the other objects moved homogenously compared to when moved in a variety of directions. A possible neural correlate of this effect may arise in the population activity of the intermediate/deep layers of the optic tectum. In these layers the neural responses to a moving element in the receptive field (RF) were suppressed when additional elements moved in the surround. However, when the surrounding elements all moved in one direction (homogeneously moving) they induced less suppression of the response compared to non-homogenously moving elements. Moreover, neural responses were more sensitive to the homogeneity of the background motion than to motion-direction contrasts between the receptive field and the surround. The findings suggest similar principles of saliency-by-motion in an avian species as in humans, and show a locus in the optic tectum where the underlying neural circuitry may exist. 
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  • Claudiu Constantin Nicolaescu
Tyto Alba diet in Brazil.

Sul de Minas Gerais: akodon montensis (31,8%), necromys lasiurus (30,4%), calomys cerquerai (18,11%), oligoryzomya nigripes (9,42%), cerradomys subflavus (0,72%), holochilus brasiliensis (0,72%), mus musculus (8,7%), unidentified rodent (0,72%).

1-Estação Ecológica do Tapacurá , Pernambuco: monodelphis domestica (9,7%), eumops glacinus (2,2%), molossus ater (4,3%), molossus molossus (10,8%), rattus rattus (3,2%), oryzomys subflavus (5,4%), pseudoryzomys simplex (5,4%), holochilus brasiliensis (30,1%), balomys lasiurus (19,4%), galea spixii (6,5%), thricomys apereoides (1,1%), passeriformes (1,1%), coleoptera (1,1%).

[i]2-Estação Ecológica do Tapacurá, Pernambuco:  [/i][i]Monodelphis domestica (14,9%), Gracilinanus agilis (2,0%), [/i]Cryptonanus agricolai (0,4%), unidentified marsupial (4,4%), Molossus molossus (9,7%), Galea spixii (2,0%), Holochilus sciureus (25,4%), Necromys lasiurus (8,1%), Nectomys sp. (0,4%), Rattus rattus (4,8%), unidentified rodent (0,4%), Thrichomys laurenteus (1,2%), reptiles (3,6%), birds (0,8%).

[i]Estação Ecológica do Olinda, Pernambuco: Phyllostomus discolor (0,4%), Necromys lasiurus (0,2%), Rattus rattus (26,8%), Mus musculus (16,1%), unidentified muridae (32,8%), birds (1,5%), reptiles (2,9%), arthropods (3,2%)[/i]

[i]Tyto Alba diet in Argentina.[/i]

Residencia Universitaria-Parque Biológico-Cordoba: Abrothrix illutea (1,0%), Akodon simulator (0,8%), Akodon spegazzinii (7,3%), Necromys sp. (0,3%), Andinomys edax (0,3%), Oligoryzomys brendae (14,9%), Oligoryzomys flavescens (10,7%), Calomys fecundus/venustus (18,3%), Calomys laucha/musculinus (45,8%), rattus sp. (0,2%), birds (0,2%), arthropods (0,2%).

Ingenio San Pablo-Tucuman: Akodon simulator (5,7%), Akodon spegazzinii (8,0%), Necromys sp. (4,6%), Holochilus chacarius balnearum (2,9%), Oligoryzomys brendae (9,2%), O. flavescens (21,8%), C. fecundus/venustus (37,4%), C. laucha/musculinus (3,4%), Phyllotys anitae (1,1%), rattus sp. (2,3%), chiroptera (1,1%), birds (2,3%).

Escuela de Agricultura y Sacarotecnia-Tucuman: Thylamys sp. (1,6%), Akodon simulator (4,9%), Akodon spegazzinii (9,8%), Oligoryzomys brendae (9,8%), O. flavescens (16,4%), C. fecundus/venustus (32,8%), C. laucha/musculinus (24,6%), 

Finca Buena Voluntad-Jujuy: Thylamys sp. (3,3%), Akodon caenosus (20,9%), Akodon simulator (4,8%), Necromys lactens (0,1%), Oxymycterus paramensis (2,1%), Andinomys edax (0,4%), Oligoryzomys brendae (25,3%), O. flavescens (4,7%), C. fecundus/venustus (18,8%),  C. laucha/musculinus (18,0%), mus sp. (0,1%), chiroptera (0,7%), birds (0,3%), arthropod  (0,4%).

Villa Padre Monti-Tucuman: Thylamys sp. (0,7%), Akodon simulator (15,0%), Akodon spegazzinii (16,4%), Oxymycterus paramensis (0,1%), Oligoryzomys brendae (28,7%), O. flavescens (5,4%), C. fecundus/venustus (32,7%), C. laucha/musculinus (0,19%), cavia sp (1,76%), birds (0,74%).

Quebrada Los Sosa-Tucuman: Thylamys sp. (1.0%), Abrothrix illutea (5,2%), Akodon caenosus (1,0%), Akodon simulator (2,1%), Akodon spegazzinii (60,8%), Oxymycterus wayku (1,0%), Andinomys edax (2,1%), Oligoryzomys brendae (9,3%), O. flavescens (9,3%), C. laucha/musculinus (1,0%), Phyllotys anitae (6,2%), birds (1,0%).

Localidad rural-Entre Ríos: cavia aperea  (1,45%), akodon azarae (17,39%), calomys laucha (43,84%), holochilus brasiliensis (0,36%), oligoryzomya flavescens (31,16%), oxymycterus rufus (2,9%), reithrodon typicus (0,72%), mus musculos (0,36%), rattus sp. (0,36%), lepus europaeus (0,36%), passeriformes (0,72%), Leptodactylus sp. (0,36%).

Tyto alba diet in Ecuador

Quito: phyllotis haggardi (39), reinthrodontomys soderstromi (20), oligoryzomys sp. (1), mus musculus (8), sylvilagus brasiliensis (4).

Provincia de Chimborazo: Marmosops impavidus (1), Aegialomys xanthaeolus (8), Akodon aerosus (1),
Akodon mollis (2), akodon sp. (2), Ichthyomys hydrobates (1), Melanomys sp (18), Microryzomys altissimus (3), Microryzomys minutus (3), Microryzomys sp. (48), Oligoryzomys destructor (5), Oligoryzomys sp. (63), Phyllotis andium (3), Sigmodon peruanus (46), Sigmodon alstoni (16), Proechimys decumanus (2), unidentified rodent (12), Mus musculus (57), Rattus rattus (2), Sylvilagus brasiliensis (3), birds (3), reptiles (2).

Ciudad de Cuenca: coleoptera (18), squamata (4), passeriformes (2), akodon mollis (15), microryzomys sp (13), oligoryzomys spodiurus (1), mus musculus (14), rattus rattus (86), desmodus rotundus (1).

Provincia de Guayas: didelphis sp (4), marmosa simonsis (7), Artibeus fraterculus (1), sylvilagus brasiliensis (1), Sigmodon peruanus (35), Proechimys decumanus (8), Aegialomys xanthaeolus (29), Transandinomys sp. (2).

Tyto Alba diet in Colombia

Este de los Andes de Colombia: Akodon affinis (33), Heteromys australis (2), Microryzomys sp. (66), Nephelomys albigularis (1), Neusticomys sp. (10), rattus sp (4), Reithrodontomys mexicanus (16), Sigmodontinae unidentified (177), Marmosops sp. (7), Cryptotis sp. (106), Sturnira sp. (1), Columba livia (2), Elaenia frantzii (2), Zonotrichia capensis (2), Myioborus ornatus (1), Sporophila sp. (1), Passeriformes unidentified (2), unidentified anura (37), Insecta (7).

Antioquia: cryptotis sp. (40), marmosa (4), carollia (1), Melanomys caliginosus (6), Handleyomys fuscatus (3), rattus sp. (6), Akodon affinis (10), Nephelomys albigularis (6), Reithrodontomys mexicanus (2), Sigmodontinae (33), birds (1), anura (35), coleoptera (7), hemiptera (29).

Tyto Alba diet in Peru

Quebrada de los burros: phyllotus limatus (6), mus musculus (118), geositta sp. (1), Tropidurus peruvianus (22), Liolaemus pantherinus (1).

Tyto Alba diet in Bolivia

Estacion Biologica Beni: gracilinanus (1), sturnira sp (3), eptesicus sp (7), laciurus sp (7), myotis sp (200), molossops (6), molossus molossus (69), molossus rufus (1), oligoryzomys sp (3), oryzomys nitidus (4), oryzomys capito (1), oxymycterus sp (1), Holochilus sciureus (86), balomys sp (1), cavia tschudii (149), passeriformes (28).

Santa Cruz del Valle Ameno: cavia sp (39), oryzomys sp (2), akodon sp (1), thylamys sp (2), didelphis sp (1), unidentified mammals (8), birds (5), insect (10).
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