Center for Animal Welfare Legal Protection    
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Published data on the adverse impact of neglected dogs on the wild fauna

This material is prepared by Yevgeny Ilyinsky and Vladimir Rybalko

Russian studies:

(see also Wild animals of RF which are exterminated by stray dogs )

1. "The impact of landscape anthropogenic transformation on the population of land vertebrates", theses of an all-Union meeting, Moscow, 1987.

The wolf and stray dogs problem.
T.K. Baratashvili. Ministry of Forestry of the Georgian SSR, Tbilisi.

      "Stray and feral dogs feel quite at home in Borzhomi Reserve. Here, they whelp and bring up their posterity, chase wild animals: the deer, the roe. Stray and feral dogs hunt hoofed animals singly, in pairs or in packs made up of a large number of individuals, they chase hoofed animals in concert, all of them barking. Among the 21 victim of the dogs registered in 1978-1980, there were 20 roes and only one deer. Half the dogs excrements contained roe remnants. More often than not, the dogs kill the young animals and pregnant females..."

The impact of the human factor on the mammalian fauna of suburban forests.
V.I. Telegin, N.G. Ivleva, Forest-Protection Experimental Station TsSBS, Siberian Division, USSR Academy of Sciences, Novossibirsk

      "The impact of the human factor on the mammalian fauna may be detrimental due to the high level of recreation, poaching, forestry operations during the breeding season, feral dogs and cats.
      The numbers of the blue hare rose from 27 individuals at the beginning of work (1964) to 120-150 individuals to remain at that level. A limiting factor for increase in the blue hare population is the location in the USSR Acad. Sci. Siberian Division area of 26 community gardens and plantations of the Central Siberian Botanical Gardens, in addition, up to 50% of the population is annually destroyed by poachers and feral dogs or cats....
      The populations of the badger, marmot and Mustelidae have declined. Those animals breed slowly and often fall prey to feral dogs or poachers".

On the human impact on the distribution and numbers of the Altai marmot on the south-facing slope of the Ketmen Range.
Zh.M. Myrzabekov, Zh.K. Kenzhebayev, Central Asian NIPCHI, Alma-Ata

"Numerous animals, particularly, young are killed by shepherd dogs, each flock of sheep having at least three such dogs. The above factors have directly affected the distribution pattern and number of the marmot"

2. Ryabov L.S. Stray and feral dogs in the Voronezh Region // Bulletin of the Moscow Society of Naturalists (MOIP), Biological Department. Moscow, 1979. Vol. 84. Vyp. 4. p.18 - 27.

P. 18. "Feral dogs dwelling in the where there are many deer, normally hunt deer and kill livestock or poultry only rarely".
P. 19. "Usman dogs show well-defined specialization in killing red deer. We know of 15 instances of dogs chasing red deer on the snow; and three times, chasing roe deer; but the results of the hunt are unknown."
P. 19 - 20. "In addition, 11 instances of wounding by dogs of various wild ungulates, 45 ungulate individuals having been killed. First, invariably the hind legs of the prey were injured; subsequently, the belly. Red deer accounted for 95% of the wounded and killed animal, in two instances, carnivores attacked young wild boars and once killed a wild boar."
P. 20. "With regard to deer, dogs most frequently killed young of the year (70%); females accounting for 60% (young predominating; occasionally, middle-aged and adults)), 40%, males (largely, young, weakened by the rut)."
P. 20. "Four instances are known where dogs chased antlered deer (both young and old) onto the ice; and once, a two-year-old female. All the animals were killed. In a deer crashed under the ice, the dogs would sit around the ice hole, waiting for the deer to become drowned". "Some dogs, knowing the sites of deer winter supplemental feeding, attacked the deer at troughs". "In the course of one hunt, dogs managed to kill not more than a single deer".
P. 21. "West of the Usman forest, <...> a pack of 5 - 6 dogs was frequently seen... . The pack was sighted in the fields and ravines where the dogs were hunting hares ".
P. 21. "In the south of the Novousmansky District, in the vicinity of the Novoronezhsky village, feral dogs appeared in 1971." In December 1974, an instance of four dogs chasing a wild boar was recorded; and in May 1975, five dogs surrounded and started mauling a year-old moose until passers-by drove them away ".
P. 21. "Once a big male dog attacked the hunter V.M. Fetisov, and the other five dogs of the pack followed suit. This is not until a shot was fired that the pack dispersed. ".
P. 21. (Focus in the Anninsky District) "In some cases, in the presence of humans a pack of dogs killed and devoured a small piglet in the sty within minutes and on a sheep farm killed 22 sheep during the night".
P.22. "Dogs chased deer (humans fought them off to save wounded females), chased roe deer and hares." "The dogs would use fox dens for shelter, and hare remains were found near those dens ".
P. 22. "Not long ago in northeastern Voronezh Region, the forests of the Khoper Reserve, had a large habitat of "forest dogs" that mostly hunted axis deer".
P. 22. (In 1969 - 1973 at Novokhopersk) "dogs would chase axis deer, moose, and hares. Sites were repeatedly found where dogs killed young deer and young wild boars. In the November 1973, a pack of 8 dogs in the Lake Zhletoyarnoye region chased a big antlered deer into the Khoper River."
P. 22. (The right-hand bank of the Don River) "In the early May 1974? A litter of a big dog (4 pups) was found in a dug-up fox den between Semiluki and Devitsa village. There were three killed fox pups near the den."
P.23. "In the June-July 1973, on the Kasenny Buyarak farm, feral dogs attacked turkeys, and in the Lebyazhye village a pack of dogs twice killed up to 20 geese in a single raid. In the August 1973 dogs n two night raids killed 45 sheep in an enclosure. Dogs frequently chase hares."
P.23 - 24. (Ostrogozhensky District) "The main fodder of the dogs is the garbage of the city refuse dump. Hunters repeatedly watched the tracks of dogs chasing young wild boars in the forest; once a wounded moose; and found the remains of the eaten-up hares."
P.25. (Liskinsky District) "Some instances were recorded of dogs attacking moose ".
P. 25. (Kalcheevsky District) "Cases of the dog hunt of roe-deer were recorded. They twice killed hunting dogs in the presence of humans."

3. G.A. Novikov. Fundamentals of General Ecology and Environmental Protection. - Leningrad: Leningrad University Publ., 1979, 352 p.
Table.
Causes of the destruction of wild species of mammals and birds in the 17th-20th centuries.
(after Zedlag, 1975)
Cause of deathNumber of species
MammalsBirds
Commercial hunting1615
Sporting hunting63
Gathering of eggs, nestlings-1
Capture for zoos-3
Superstition1-
Destruction as proposed pests156
Felling713
Ploughing-up, housing125
Under the impact of sheep, goats or rabbits-7
Destruction by domestic animals (dogs, cats, pigs)922
Infections-3

      (omment by site editor: It follows from the table that according to the number of species destroyed over three centuries (XVII- XX centuries) domestic mammals (dogs, cats, pigs) rank fourth, and in terms of the number of destroyed birds, rank third. However, in terms of the destroyed species (mammals + birds = 31 species) domestic animals inflicted damage equal to commercial hunting (also 31 destroyed species!), which is suggestive of domestic animals being extremely harmful to wildlife. Judging from other published studies, neglected dogs (stray or feral) are clearly the most responsible for that destruction.
      It should also be taken into account that in relation to Russia the problem of the adverse impact of neglected animals (mostly dogs) on the wildlife may be greater than the table data by several orders of magnitude. The reason for that is that are millions of abandoned cats and dogs that are breeding in the streets. Those animals were abandoned as a result of an explosion of commercial breeding of cats and dogs in the 1990s when the majority of crosses, non-purebred and even purebred animals lost their value and commercial price that they had during the USSR. The situation is aggravated by the absence in Russia of legislation ensuring the economic mechanisms for leveling off supply and demand for cats and dogs, which in Europe and the United State provide a basis for prevention of cats and dogs from finding themselves in the streets and concurrently, environmental protection and prevention from cruel treatment of animals.)

4. Collected papers of the Scientific and Practical Conference "Animals in the City ". Timiryazev Moscow Agricultural Academy jointly with the Severtsov Institute of Evolution and Ecology Research, Vol. 1-2, 2000-2003.

Game Animals of the Forest-Park Zone of Moscow: Protection Problems
P.S. Marchenko, A.T. Bozhansky
Russian State Agrarian Correspondence University,
Balashikha, Russia

      "In addition to the above factors, there is a considerable adverse impact of a group of stray dogs, which reduce both the population of large ungulates (the moose, roe, deer, wild boar) and nesting habitats of forest and field game birds."
      "In the system of the regulation of undesirable species of natural and man-made cenoses, the control of stray dogs ranks highest among the biotechnical measures undertaken in the forest-park zone of Moscow. The results of those measures are presented in Table 4"

Table 4. Stray dogs in the forest-park one of Moscow and their number regulation.

YearRecorded in forest-parksRemoved from forest-parksDestroyed dens
19951950125015
19961610168820
19971560136011
1998140095010
199913506804
200011403402

"Thus, the worst damage inflicted on the forest-park zone is that by stray dogs ..."

Hares in the city
A.V. Berezin
Omsk State Pedagogical Institute, Omsk, Russia

      "In fruit gardens and parks, stray dogs may feed on hares as well as on small Muridae...."
      "The authors watched stray dogs eating up captured cats ...".

On the avifauna of the city of Arkhangelsk
V.A. Andreev.
Arkhangelsk Regional Area Study Museum, Arkhangelsk, Russia

      "It should be noted that in the city there are high numbers of dogs: about 30 thousand. On account of stray dogs and cats, and, occasionally, "with the assistance" of domestic animals (i.e., having masters) the mortality of land-nesting birds, which in the central part of the city occupy one tenth of the city area reaches 82%."

Herpetofauna of the city of Krasnodar
S.V. Ostrovskikh, G.K. Plotnikov
Kuban State University,
Krasnodar, Russia

      "The breeding success of the urban tortoise population appears to be low. The sites suitable for laying eggs are not numerous, and the nest chambers themselves are often destroyed by cats, dogs and Corvidae."

Big mammals of the outskirts of Moscow
A.V. Matyukhin, D.A. Maslov, S.S. Blokhin, Yu.A. Medvedev
Severtsov Institute of Ecology and Evolution Research, Russian Academy of Sciences

      " ... Feral dogs were recorded at the site throughout the year. During the spring and winter season, pack of dogs number dozens of individuals, and, undoubtedly, are hazardous to human health. In the summer 1998, and individual with rabies symptoms was recorded. Both stray dogs and domestic dogs taken out by residents of Solntsevo and Novoperedelkino are constantly dangerous to land-nesting birds of wastelands wagtails, red-throated bluethroats and mallards. In Solntsevo and Novoperedelkino, the numbers of feral dogs are not regulated at all, and they naturally are dangerous to humans. In fact, we repeatedly recorded attacks of dog packs of 5-7 individuals on humans in the very Solntsevo micro-district. On one occasion, a mother could hardly save her child from attacking dogs."

5. Ecological types of stray dogs.
A.D. Poyarkov, A.A. Tupikin.
Severtsov Institute of Ecology and Evoltuion Research, Russian Academy of Sciences, Moscow.

      "...Hunting Muridae, rats and feral cats (by stray dog site Ed.) is referred to by us as predation under urban conditions. This strategy is not the main one under urban conditions except a few highly-specialized individuals as it is the least profitable energetically. Along with that, it is a supplementary and the most attractive emotionally for a wide range of stray dogs.
      Thus, the range of logically possible types can be represented as the following matrix or table."
DependantsBeggarsGatherersPredators
Conventionally neglected++++++++
Stray++++++++++++
Wild--+++++++

      "In the present table stands for impossibility of the existence of a given ecological type, whereas + designates the score of the occurrence of the combination concerned. The most frequent is the combination ++++ and the least frequent is +."
      (omment by site editor: the study findings support evidence obtained by our organizations to the effect that all the ecological types of stray dogs destroy homeless cats extensively. This appears to be one of the main contradictions of the concept of number regulation of homeless animals by neutering alone to be subsequently returned to their original habitats. In this case, homeless cats are actually utilized by homeless dogs)

6. Official document of the Government of Moscow
"The Red Data Book of the City of Moscow", 2001 (the first edition).

Some excerpts from the Red Data Book of Moscow,
regarding the adverse impact of neglected dogs on the wildlife of the original natural ecosystem.

      (omment by site editor: Some wild animals that disappeared from the city area under the impact of neglected dogs (including axis deer, roe deer, etc.) cannot be listed in the Red Data Book of Moscow because they do not belong to the natural original ecosystem of the region concerned. Other animals (e.g., the badger) are not in the Red Data Book of Moscow either because they had been entirely exterminated in the city area by neglected dogs before the publication of the Red Data Book of Moscow.
      It is noteworthy that the work on the first edition of the Red Data Book of Moscow was done during the time when neglected dogs were removed from the environment in a centralized manner. Now that the removal of dogs from the environment has been virtually discontinued and their numbers increased by several times, the adverse effect of neglected dogs indicated in the first edition of the Red Data Book of Moscow has augmented on a multiple basis. The latter has, according to the authors of the Red Data Book of Moscow has resulted in extermination of the majority of mammals, land-nesting birds and amphibians listed in the first edition of the Red Data Book of Moscow).

European hedgehog

      "Limiting factors: ... Active chasing by neglected dogs. ..."
      "Measures required for the conservation of the species: ...Solution to the problem of neglected dogs and banning free-ranging of hunting dogs in protected areas and forest parks. ..."

Ermine

      "Limiting factors: ... Chasing by neglected dogs, particularly hazardous for the ermine during the breeding season."
      Measures required for the conservation of the species: ... Solution to the species of neglected dogs, banning of the free ranging of dogs where the ermine breeds ..."

Weasel

      "Limiting factors: ... Chasing and killing of weasels by neglected dogs. Digging up by those dogs of litter dens ..."

Blue hare

      " Limiting factors: ... Chasing by neglected dogs. Digging up by those dogs, which destroy not only young hares byt also adult hares."
      " Measures required for the conservation of the species: ... Solution to the species of neglected dogs. ..."

European hare

      "Limiting factors: ... Destruction of young hares by neglected dogs ..."
      " Measures required for the conservation of the species: ...Solution to the problem of neglected dogs and banning free-ranging of hunting dogs in the species habitats. ..."

Common partridge

      "Limiting factors: ... Augmented (compared with other species) hazard of destruction of clutches and broods of the common partridges by crows or dogs. ..."
      "Measures required for the conservation of the species: ... Preventive work with hunting dog owners in the neighborhood regions of the city. ..."

Quail

      "Limiting factors: ... Frequent starting by humans or dogs of females with broods when they are feeding or resting on dirt roads or other sunl-heated sites. ..."
      "Measures required for the conservation of the species: ... Briefing of residents of the districts near which quail habitats are located to the effect that release of dogs at those sites in summer is inadmissible. ..."

Woodcock

      "Limiting factors: ... Chasing by neglected dogs . ..."
      "Measures required for the conservation of the species: ... Augmented supervision of the ban on making bonfires and free-ranging of dogs in Moscow protected areas ..."

Yellow wagtail

      "Limiting factors: ... Disturbance by humans and dogs. ..."

Also, see:
Letter of Moscow Red Data Book Commission

Press-conference at RIA NOVOSTI 20.01.2005 with the participation of Executive Editor of Moscow Red Data Book, Chief of Laboratory of VNII of Nature Conservation Candidate of Biology Boris Samoilov

Interview of Executive editor of the Moscow Red Data Book in the NEZAVISIMAYA GAZETA 31.01.2006: latest data on the number of species entered in the Red Data Book, conserved in Moscow natural complexes

7. Official document of the Government of the Russian Federation
"Red Data Book of the Russian Federation (animals)", 2001

Some excerpts from the RF Red Data Book

Daurian hedgehog

Order Insectivora, Family Erinaceidae

      "Numbers and limiting factors: Among the limiting factors for the species, the most substantial are forest and steppe fires, the application of pesticides, harvesting operations and free-ranging dogs ... "
      "Taken and needed protection measures: ...Restriction of free-ranging of dogs."

Medny blue polar fox
Order Carnivora , Family Canidae

      "Numbers and limiting factors: The direct cause of population decline is an epizootics of ear scabies.... It is quite possible that the ear mite was later imported with dogs... "
      "The taken and needed protection measures: ... The access to dogs to Medny Island should be urgently and entirely banned. So far, dogs get to the Medny Island with tourists, hunters and scientific expeditions."

Pallas cat
Order Carnivora, Family Felidae

      "Numbers and limiting factors: The greatest impact on the decline of the numbers is that of the headlight hunt, free-ranging of dogs, massive use of loops and traps to capture hares and foxes."

Aleutian Canada goose
Order Anseriformes, Family Atenidae

      "Numbers and limiting factors: The cause of the disastrous decline of the numbers and complete extinction of the western population in the early 20th century was the distribution of the polar fox and the fox on the islands and also the import of dogs and rats."

Asian red-breasted snipe
Order Charadriiformes, Family Scolopacidae

      "Numbers and limiting factors: The main limiting factors are the destruction of nests when water level is high; the predation of the common and herring gull, buzzards, carrion crow; and near human settlements, of dogs and Norway rats; destruction of modification of the nesting habitats."

8. Wagner B.B., Zakharova N.Yu. Animals of Moscow Environs. Moscow: Moskovsky Liceum, 2003

      p. 19 "... With such prolificacy, the roe deer population could have doubled each year, yet the small deer has too many enemies. ... But the main harm on the population is inflicted by hordes of stray dogs and by poachers. As a result, these fine animals grow in number very slowly, and apparently it is too early to say that roe deer has settled down in Moscow environs for good."
      p. 22 "... It should be noted that acclimatization of sika deer in Moscow Region proceed with great difficulties. ... The reason for this, as in the case of roe deer, are, above all, winters with abundant snow, when many deers die due to lack of fodder, plus attacks by hordes of wolves. Stray dogs do not pity sika deer, either."
      p. 36 "... Of domestic animals, wolves dislike dogs most: they feel ineradicable animosity towards the dogs. In this respect, the gray predators play a positive role in Moscow Region nature: where there are wolves, the hordes of stray dogs disappear the hordes being the scourge of Moscow, and not only Moscow, woods. In the Oka reserve, located in Ryazan Region near to Moscow Region, such stray dogs nearly killed the entire sika deer population, which declined in a matter of several years from 100 to 10 heads. However, after the 1973 comeback of wolves in the reserve, the dogs were exterminated and the population of gorgeous deer stabilized."
      p. 37 "... Damage to cattle resulting from attacks by wolves is virtually negligible nowadays. The activity of this sanitarian of the wood is much more useful in that it kills the diseased hoofed animals, thereby stopping the spread of epidemics, and eliminates the gangs of stray dogs..

Also, see published articles and reports:
Olga Shcherbakova, Deers threatened by stray dogs (Mir Novostei dated 14.06.2005)

Yury Krasnov, Tender domestic killers (National game journal HUNT No 9, 2005)

Conference Stray dog researching problems at the RAS Severtsov Institute of Evolution and Ecology

Foreign studies:

      1. Denney, R.N. 1974. The impact of uncontrolled dogs on wildlife and livestock. Trans. North. Amer. Wildl. and Nat. Res. Conf. 39:257-291.
      In a nationwide survey, the dog was identified as the number-one killer of wildlife. More than 20,000 deer were reported killed in 32 states, based on adjusted estimates from known kills on opinion estimates".

      2. Jeffrey S. Green, Philip S. Gipson, 1994, Feral Dogs, Prevention and control of wildlife damage: Great Plains Agricultural Council, Wildlife Committee and oth.
      "Feral dogs may become skilled at hunting in groups for small game such as rabbits and hares and large game including deer and even moose. Some wildlife managers feel that feral dogs are a serious threat to deer, especially in areas with heavy snows...
      Feral dog commonly kill house cats, and they may injure or kill domestic dogs. In areas where people have not hunted and trapped feral dogs, the dogs may not have developed fear of humans, and in those instances such dogs may attack people, especially children. This can be a serious problem in areas where feral dogs feed at and live around garbage dumps near human dwellings. Such situations occur most frequently around small remote towns.
      On the Galapagos Islands, feral dogs have significantly impacted native populations of tortoises, iguanas, and birds.
      Damage to wildlife, especially deer, small game, and birds was considered the primary problem caused by dogs. Damage to game animals may be a serious local problem...."


      3. Kreeger T.J. 1977. Impact of Dog Predation on Minnesota Whitetail Deer. The Minnesota Academy of Science, Vol. 43. p. 8 - 13.
      Kreeger is a member of the Department of Biology, University of Minnesota, Duluth.
      Abstract. Conservation officers conducted a study on the intensity of dog hunting the white-tailed (Virginian) deer, the latter being the most common American deer. 124 rangers were interviewed, out of which number, 95 confirmed the facts of dogs killing deer. Between April 1, 1975 and March 31, 1976 dogs killed 407 deer. The majority of the dogs were domestic free-ranging dogs (94%). Occasionally they mixed with true feral dogs to form packs. The American researcher . . Beck (1973) said that in the early 1970s, from one third to half of house dogs in the United States were free-ranging. The most dangerous to deer were hounds, German shepherds and Airedale terriers. In Minnesota, one of a few states where wolves remained, the number of deer killed by dogs is far smaller (by 30 times) than that killed by wolves. But dogs often did not kill deer for consumption .
      P.10-11: "There were some instance, however, where one or a few dogs killed a large number of deer without consuming them. In other words, they killed them for the sake of killing Beck (1973) claims that killing without consumption of prey occurs in dogs, being a behavior patter that developed in the course of domestication. An example is found in roughly 40 deer killed by two dogs in St. Croix National Park. Also, a conservation officer mentioned in an interview that in one forest area 22 deer were killed by a single dog in March, 1977. Another officer pointed out that a single dog was responsible for at least 50 dead deer within two weeks. Such instances of massive killings may give an idea of a higher intensity of dog attacks compared with the average number for the state."
      And another aspect indicated by Kreeger (p. 11): "The dog and deer problem is not only considered in terms of direct killing by the animals but also special reference to the disturbance factor. Studies on the dog and the wolf reveal the fundamental difference of their behavior while chasing prey. Although wolves are more successful in killing the prey, they quickly "determine the situation where chasing is useless. Dogs commonly chase deer because they enjoy chase."
      The results are as follows (P. 11): "According to Denny (1974), Connecticut authorities reported that about 450 deer had died on highways, having been chased onto them by dogs. orbett et al.,(1971) demonstrated that numerous injuries as cuts, haematomas and broken bones in deer were the result of cross-country chase by dogs."

      4. Domestic Dogs as Predators on Deer, Wildlife Society Bulletin, Vol. 6, No. 1, Spring, 1978
      "...popular articles consider free-roaming pet dogs to be a definite threat to deer populations (Bowers 1953, Ward 1954, Brazda 1957, Giles 1960, Cochran 1967, Houston 1968, Morrison 1968, Caras 1973), and evidence from Colorado (Denney 1974) and northern Idaho supports this assertion."
      "In the Coeur d'Alene River drainage of northern Idaho, communities and residences are interspersed throughout the deer winter range, and harassment of deer by dogs has increased as homes are built in forested areas where deer formerly had little disturbance. Jn 1975, 39 incidents of dogs chasing deer were witnessed by an Idaho Fish and Game Department conservation officer or were reported to him by concerned citizens or the sheriffs department; these chases directly resulted in the deaths of 12 white-tailed and mule deer (Table 1)- In no case was any abnormality apparent in the deer. Deer were either caught and killed, drowned after being chased into the river, or were crippled and had to be shot. Many more encounters undoubtedly occurred which were either not witnessed or not reported."

Table 1. Details of 39 reported incidents of dogs chasing deer, Coeur d'Alene River drainage, 1975.

Number of incidents
Reporting method:
      Reported by citizen
      Reported by sheriffs department
      Witnessed by conservation officer

27
4
8
When officer arrived:
      Dogs still chasing deer
      Dogs cease chasing and disperse
      Chase no longer occurring *

7
9
23
Fate of deer:
      Deer got away from dogs
      Deer chased into river, not hurt
      Deer crippled, got away

Deer not directly killed
23
2
2

27
      Deer killed by dogs
      Deer chased into river, drowned
      Deer crippled, shot by officer

Direct deer mortality
8
1
3

12
Species and sex of killed deer:
      Mule deer buck
      Whitetail buck
      Mule deer doe
      Whitetail doe
      Whitetail female fawn
1
1
2
6
2
      Incidents where dogs were shot
      Number of dogs shot
7
14

* Chase no longer occurring because dogs had dispersed, concerned citizens had chased dogs away, or dogs continued the chase out of sight and could not be found.


      "In addition to direct mortality, indirect consequences of chasing may prove no less serious. Disturbed deer may run out onto highways or get cut or entangled in the barbed wire fence or mauled as a result of falls or leg injuries (Jiles 1960). The majority of chase instances occurred in winter; and the bulk of mortality cases, in late winter. Dogs have an advantage over deer when they run on ice-crusted snow: deer crash through the ice crust and dogs run over the crust. During severe winters, that factor may prove of major importance, in case deer has to spend time and energy to escape from chasing dogs instead of expending energy on foraging."

April, 2005

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