Carnivore prey selection overview thread
Aug 5, 2013 21:56:32 GMT 5
coherentsheaf and theropod like this
Post by creature386 on Aug 5, 2013 21:56:32 GMT 5
This is an overview thread on the prey selection of carnivores. You can post studies about the prey selection here.
I'll start:
Cheetah:
www.zbs.bialowieza.pl/publ/pdf/1596.pdf
Leopard:
www.researchgate.net/publication/227517462_Prey_preferences_of_the_leopard_(Panthera_pardus)/file/9fcfd50a570bc3c166.pdf
Spotted Hyena:www.zbs.bialowieza.pl/publ/pdf/1598.pdf
African Wild Dog:www.jstor.org/discover/10.2307/3798360?uid=3737864&uid=2&uid=4&sid=21102528925123
Lion:
www.ibs.bialowieza.pl/g2/pdf/1595.pdf
Tiger:
www.researchgate.net/publication/233791217_Prey_preferences_tiger_2012_J_Zool_286_221-231/file/79e4150b8868e94613.pdf (PDF download link)
I'll start:
Cheetah:
As a charismatic carnivore that is vulnerable to extinction, many studies have been conducted on predation by the cheetah (Acinonyx jubatus). Cheetah are generally considered to capture medium-sized prey; however, which species are actually preferred and why has yet to be addressed. We used data from 21 published and two unpublished studies from six countries throughout the distribution of the cheetah to determine which prey species were preferred and which were avoided using Jacobs’ index. The mean Jacobs’ index value for each prey species was used as the dependent variable in multiple regression, with prey abundance and prey body mass as predictive variables. Cheetah prefer to kill and actually kill the most available prey present at a site within a body mass range of 23–56 kg with a peak (mode) at 36 kg. Blesbok, impala, Thomson’s and Grant’s gazelles, and springbok
are significantly preferred, whereas prey outside this range are generally avoided. The morphological adaptations of the cheetah appear to have evolved to capture medium-sized prey that can be subdued with minimal risk of injury. Coincidentally, these species can be consumed rapidly before kleptoparasites arrive. These results are discussed through the premise of optimality theory whereby decisions made by the predator maximize the net energetic benefits of foraging. Information is also presented that allows conservation managers to determine which prey species should be in adequate numbers at cheetah reintroduction sites to support a cheetah population. Conversely, these results will illustrate which potential prey species of local conservation concern should be monitored for impact from cheetahs as several species are likely to be preyed upon more frequently than
others.
are significantly preferred, whereas prey outside this range are generally avoided. The morphological adaptations of the cheetah appear to have evolved to capture medium-sized prey that can be subdued with minimal risk of injury. Coincidentally, these species can be consumed rapidly before kleptoparasites arrive. These results are discussed through the premise of optimality theory whereby decisions made by the predator maximize the net energetic benefits of foraging. Information is also presented that allows conservation managers to determine which prey species should be in adequate numbers at cheetah reintroduction sites to support a cheetah population. Conversely, these results will illustrate which potential prey species of local conservation concern should be monitored for impact from cheetahs as several species are likely to be preyed upon more frequently than
others.
Leopard:
Leopards (Panthera pardus) have a catholic diet and are generally thought to prey on medium-sized ungulates; however, knowledge on which species are actually preferred and avoided is lacking, along with an understanding of why such preferences arise. Twenty-nine published and four unpublished studies of leopard diet that had relative prey abundance estimates associated with them were analysed from 13 countries in 41 different spatial locations or temporal periods throughout the distribution of the leopard. A Jacobs’ index value was calculated for each prey species in each study and the mean of these was then tested against a mean of 0 using t or sign tests for preference or avoidance. Leopards preferentially prey upon species within a weight range of 10–40 kg. Regression plots suggest that the most preferred mass of leopard prey is 25 kg, whereas the mean body mass of significantly preferred prey is 23 kg. Leopards prefer prey within this body mass range, which occur in small herds, in dense habitat and afford the hunter minimal risk of injury during capture. Consequently, impala, bushbuck and common duiker are significantly preferred, with chital likely to also be preferred with a larger sample size from Asian sites. Species outside the preferred weight range are generally avoided, as are species that are restricted to open vegetation or that have sufficient anti-predator strategies. The ratio of mean leopard body mass with that of their preferred prey is less than 1 and may be a reflection of their solitary hunting strategy. This model will allow us to predict the diet of leopards in areas where dietary information is lacking, also providing information to assist wildlife managers and conservation bodies on predator carrying capacity and predator–prey interactions.
Spotted Hyena:
Spotted hyaenas (Crocuta crocuta) were once considered mere scavengers; however, detailed research revealed that they are very efficient predators. Information on what spotted hyaenas actually prefer to prey on and what they avoid is lacking, as well as the factors that influence prey selection. Data from 14 published and one unpublished study from six countries throughout the distribution of the spotted hyaena were used to determine which prey species were preferred and which were avoided using Jacobs’ index. The mean of these values for each species was used as the dependent variable in multiple regression, with prey abundance and prey body mass as predictive variables. In stark contrast to the rest of Africa’s large predator guild, spotted hyaenas do not preferentially prey on any species. Also surprisingly, only buffalo, giraffe and plains zebra are significantly avoided. Spotted hyaena most prefer prey within a body mass range of 56–182 kg, with a mode of 102 kg. The dietary niche breadth of the spotted hyaena is similar to that of the lion (Panthera leo), and the two species have a 58.6% actual prey species overlap and a 68.8%preferred prey species overlap. These results highlight the flexible and unselective nature of spotted hyaena predation and are probably a reason for the species’ success throughout its range, despite a large degree of dietary overlap with lions.
African Wild Dog:
African wild dog (Lycaon pictus) predation was observed in Ngorongoro Crater, Tanzania, between September, 1964, and July, 1965, when packs were in residence. The original pack of 21 dogs remained only 4 months, but 7 and then 6 members of the group reappeared in the Crater at irregular intervals. The ratio of males:females was disproportionately high, and the single B**** in the small pack had a litter of 9 in which there was only one female. The pack functions primarily as a hunting unit, cooperating closely in killing and mutual defense, subordinating individual to group activity, with strong discipline during the chase and unusually amicable relations between members. A regular leader selected and ran down the prey, but there was no other sign of a rank hierarchy. Fights are very rare. A Greeting ceremony based on infantile begging functions to promote pack harmony, and appeasement behavior substitutes for aggression when dogs are competing over meat. Wild dogs hunt primarily by sight and by daylight. The pack often approaches herds of prey within several hundred yards, but the particular quarry is selected only after the chase begins. They do not run in relays as commonly supposed. The leader can overtake the fleetest game usually within 2 miles. While the others lag behind, one or two dogs maintain intervals of 100 yards or more behind the leader, in positions to intercept the quarry if it circles or begins to dodge. As soon as small prey is caught, the pack pulls it apart; large game is worried from the rear until it falls from exhaustion and shock. Of 50 kills observed, Thomson's gazelles (Gazella thomsonii) made up 54 percent, newborn and juvenile wildebeest (Connochaetes taurinus) 36 percent, Grant's gazelles (Gazella granti) 8 percent, and kongoni (Alcelaphus buselaphus cokei) 2 percent. The dogs hunted regularly in early morning and late afternoon, with a success rate per chase of over 85 percent and a mean time of only 25 minutes between starting an activity cycle to capturing prey. Both large and small packs generally killed in each hunting cycle, so large packs make more efficient use of their prey resource. Reactions of prey species depend on the behavior of the wild dogs, and disturbance to game was far less than has been represented. Adult wildebeest and zebra (Equus burchelli) showed little fear of the dogs. Territorial male Thomson's gazelles, which made up 67 percent of the kills of this species, and females with concealed fawns, were most vulnerable. The spotted hyena (Crocuta crocuta) is a serious competitor capable of driving small packs from their kills. A minimum of 4-6 dogs is needed to function effectively as a pack. It is concluded that the wild dog is not the most wantonly destructive and disruptive African predator, that it is an interesting, valuable species now possibly endangered, and should be strictly protected, particularly where the small and medium-sized antelopes have increased at an alarming rate.
Lion:
Lions (Panthera leo) are generally thought to prey on medium to large ungulates. Knowledge of which species are actually preferred and which are avoided is lacking, however, as is an understanding of why such preference or avoidance may arise. An analysis of 32 studies over 48 different spatial locations or temporal periods throughout the distribution of the lion shows that it preferentially preys upon species within a weight range of 190–550 kg. The most preferred weight of lion prey is 350 kg. The mean mass of significantly preferred prey species is 290 kg and of all preferred species is 201 kg. Gemsbok, buffalo, wildebeest, giraffe and zebra are significantly preferred. Species outside the preferred weight range are generally avoided. Species within the preferred weight range that are not significantly preferred (such as roan, sable and eland) generally have features that reduce predation either morphologically (e.g. sable horns), ecologically (e.g. roan and sable occurring at low density), or behaviourally (e.g. the large herd size and increased vigilance of eland). Warthog are below the preferred weight range yet are taken in accordance with their availability and this is probably due to their sympatry with lion, their relatively slow evasion speed and their lower level of vigilance. Plots of prey preference against prey body mass follows a bell curve with a right skew that, we argue, is caused by collective hunting by lions of larger-bodied prey. Our methods can be used on all large predators and are likely to be useful in assessing competition in sympatric communities of predators, cooperative hunting and predicting predator diets. This will allow us to move beyond descriptive dietary studies to improve our predictive understanding of the mechanisms underlying predator–prey interactions.
Tiger:
Tigers (Panthera tigris) continue to decline despite the best efforts of the worldwide scientific and conservation communities. Prey depletion has been linked to this decline, but a clear definition of what constitutes preferred prey and preferred prey weight range does not exist. This is critical information if we are to assess tiger reintroduction potential, monitor unforeseen poaching of predators and prey, and successfully conserve the species. Here we reviewed the available literature on tiger diet and prey availability and calculated JacobsÂ’s electivity index scores from 3187 kills or scats of 32 prey species. We found that wild boar and sambar deer are significantly preferred by tigers, with red deer and barasingha likely to be signifi- cantly preferred also with a larger sample size. Prey body mass was the only variable that related to tiger prey preference with species weighing between 60 and 250 kg preferred by tigers yielding a ratio of predator to preferred prey of 1:1, which is similar to other solitary felids. This information can be used to predict tiger diet, carrying capacity and movement patterns, as it has been for AfricaÂ’s large predator guild, and has important implications for tiger conservation throughout its distribution.
