Poll: Who wins?
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Eurasian Otter
2 100.00%
Water Monitor
0 0%
Total 2 vote(s) 100%
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Eurasian Otter v Water Monitor
European (Eurasian) Otter - Lutra lutra
The European otter is the most widespread of all the otter species. They can be found in freshwater and coastal areas throughout Europe, in north Africa and Asia. European Otters mainly feed on fish, but they will also hunt other aquatic prey, such as amphibians. European Otters have a body length between 57 and 70 cms (22.5 - 28 inches), a tail length between 35 and 40 cms (10 - 16 inches) and they weigh between 7 and 10 kgs (15 - 22 lbs), although occasionally a large old male may reach up to 17 kg (37 lb). They have a long body and short, stocky legs. Their dense fur is brown in colour with a paler underside and they have a thick, muscular tail. On each paw they have five webbed toes which aid them in being excellent swimmers.

[Image: 640px-Fischotter%2C_Lutra_Lutra.JPG]

Water Monitor - Varanus salvator
The water monitor is a large species of monitor lizard. Breeding maturity is attained for males when they are a relatively modest 40 cm (16 in) long and weigh 1 kg (2.2 lb), and for females at 50 cm (20 in). However, they grow much larger throughout life, with males being larger than females. Adults rarely exceed 1.5–2 m (4.9–6.6 ft) in length, but the largest specimen on record, from Sri Lanka, measured 3.21 m (10.5 ft). A common mature weight of V. salvator can be 19.5 kg (43 lb). However, 80 males killed for the leather trade in Sumatra averaged only 3.42 kg (7.5 lb) and 56.6 cm (22.3 in) snout-to-vent and 142 cm (56 in) in total length; 42 females averaged only 3.52 kg (7.8 lb) and 59 cm (23 in) snout-to-vent and 149.6 cm (58.9 in) in total length, although unskinned outsized specimens weighed 16 to 20 kg (35 to 44 lb). Another study from the same area by the same authors similarly estimated mean body mass for mature specimens at 20 kg (44 lb) while yet another study found a series of adults to weigh 7.6 kg (17 lb). Their body is muscular with a long, powerful, laterally compressed tail. Water monitors are one of the most common monitor lizards found throughout Asia, and range from Sri Lanka, India, Indochina, the Malay Peninsula and various islands of Indonesia, living in areas close to water. Water monitors can be defensive, using their tail, claws, and jaws when fighting. They are excellent swimmers, using the raised fin located on their tails to steer through water. Water Monitors are carnivores, and have a wide range of foods. They are known to eat fish, frogs, rodents, birds, crabs, and snakes. They have also been known to eat turtles, as well as young crocodiles and crocodile eggs. Like the Komodo Dragon, they will often eat carrion.

[Image: water-monitor--varanus-salvator-1.jpg]

(05-15-2019, 07:57 PM)Bianjpr Wrote: Eurasian otter vs asian water monitor
[Image: wildcat10-CougarHuntingDeer.jpg]
Otter is like unexpected predator, at average weight otter has weight advantage here, which is beneficial in fight. At parity would be 50/50.
[Image: t70ok8.jpg]
Otter is more agile while the monitor has more dangerous bite
These Otters appear very wary of this Water Monitor:

Heres an African Otter killing a Monitor Lizard:

[Image: wildcat10-CougarHuntingDeer.jpg]
I wonder about how strong monitor's tail whip. There are some claims that a large monitor can break small dog's leg with its tail whip
(05-16-2019, 10:06 PM)Bianjpr Wrote: I wonder about how strong monitor's tail whip. There are some claims that a large monitor can break small dog's leg with its tail whip

I.M.O that's a claim I'd want to see a credible source for.

The water monitor seems to have a very broad weight distribution, and though some massive individuals are often seen the frequency of such individuals may be facilitated by human presence / the surplus of food it causes and would be otherwise record specimens in 'pure' habitats.

I don't know of any instances of these two species interacting, but with other species of otter :

On 29th March 2009, at around 08.00, an adult smooth-coated otter, of unknown sex, was observed in a pond at the Forestry Research Institute, Malaysia (FRIM) (3°13'49''N - 101°38'00''E) (Figure 1). The pond is approximately 200 m in diameter and surrounded by a mixture of by trees and lawns, the latter leading to a road around 50 m from the pond. Although otters have been observed there by the authors before, sightings are considered to be a rare event.

The otter was initially observed catching and eating small fish at several locations within the pond over a half-hour period. At approximately 08:30 a large water monitor lizard, approximately 110-120 cm in length, swam across the pond and climbed onto a small tree protruding from the water (Figure 2). Within seconds the otter appeared at the base of the tree and grabbed the monitors' tail in its mouth (Figure 3). Although the monitor resisted the efforts of the otter, turning its head repeatedly as if trying to bite it (Figure 4), it was eventually pulled into the water where the otter immediately climbed onto its back (Figure 5).

[Image: Goldthorpe_et_al_2010_Fig2.jpg]
Figure 2: Monitor climbing into a small tree, protruding from the water.

[Image: Goldthorpe_et_al_2010_Fig3.jpg]

Figure 3: Otter launching out of the water, grabbing the monitor lizards tail in its mouth.

[Image: Goldthorpe_et_al_2010_Fig4.jpg]
Figure 4: Monitor lizard attempting to defend itself.

[Image: Goldthorpe_et_al_2010_Fig5.jpg]Figure 5: Otter managing to dislodge the monitor lizard from the tree, immediately jumping on its back as it hits the water.

[Image: Goldthorpe_et_al_2010_Fig6.jpg]
Figure 6: The monitor lizard being dragged under water during the struggle

The ensuing struggle lasted several minutes during which the monitor seemed to put most of its effort into escape. The otter, however, seemed intent on overpowering it and dragged it underwater several times (Figure 6). At one point the otter was seen biting the back of the monitors' neck and, though it was not clear if this was a fatal bite, the monitor did cease to struggle and soon after was seen floating on its back. At this point it was assumed to be dead, though this was never actually verified. The otter then gripped the “carcass” in its jaws and swam with it back to the area where the encounter had begun. Here it appeared to push the body under a partly submerged tree-limb, as if caching it; a behaviour that is not, to this authors knowledge, recorded elsewhere.

This appears, then, to be the first record of a smooth-coated otter attacking and killing such a large animal. The motivation for the attack is unclear as, whilst simple predation would be the most obvious explanation, none of the authors actually observed the otter consuming any part of the monitor lizard during or after the attack. Predation by otters on novel and high-risk species is not unheard of: Ruiz-Olmo and Marsol (2002) cite three separate accounts of Eurasian otters (Lutra lutra) killing and eating large birds, including a red kite (Milvus milvus). However, such examples of novel prey-taking tend to be the result of reductions in natural prey species (e.g. Gallant and Sheldon, 2008) and, as detailed above, all authors had seen this otter take and consume fish from the pond with apparent ease. Other explanations should, then, be considered.
Competitive exclusion is readily observed between a wide variety of species in both the animal and plant kingdoms. However, the monitor is such a generalist in nature (Gaulke, 1991; Auliya, 2006) and the otter so predominantly piscivorous that it seems unlikely that the former would present a big enough threat to the resources of the latter as to provoke such a high-risk attack (Dr. Mark Aulia, pers. Comm.. to G. Goldthorpe).

A second alternative explanation would be the protection of pups from the monitor, which would represent a very real threat to defenseless young. Again, the records of such events are extremely rare in the literature but some observations of reptiles taking otter pups have been made. For example, Weber Rosas et al. (2008) witnessed the predation of giant otter (Pteronura brasiliensis) pups being apparently predated by a tegu (Tupinambis teguixin) in the Central Brazilian Amazon. However, it should be noted that no young have been observed at this site subsequent to the observation detailed herein.

There have been multiple observations, made over a number of years, of captive Asian small-clawed otters (Aonyx cinerea) attacking and killing monitor lizards in both Singapore Zoo (Frances Lim, n.d., in litt.) and the Singapore Night Safari (Charlene Yeong, Madhavan Vijayan, Kumar Pillai, Razak Alwi, n.d., in litt.). In at least one of these observations it was noted that the presence of monitors was tolerated until the otters started to breed, at which point they became the targets of repeated “tail-nipping” by the otters.


From this, the otter should be able to take this at similar weights at land and in water I.M.O. But at maximum weights of both species the much larger water monitor would likely prevail quickly.

(05-16-2019, 10:55 PM)Canidae Wrote: From this, the otter should be able to take this at similar weights at land and in water I.M.O. But at maximum weights of both species the much larger water monitor would likely prevail quickly.

Agree. The maximum size monitor would be a big problem for the otter

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