Prey and predator relationship in scandinavia

prey and predator relationship in scandinavia

Cycles of voles, predators, and alternative prey in boreal Sweden. A bstract in relation to variations in plant production indices in Northern Sweden. In Scandinavia wolves (Canis lupus) are at the top of the food chain. part of the predator-prey relationship but also providers of carrion to a large range of. example, prey upon or compete with commercially valuable species wolf population in Scandinavia now numbers some. – The relationship between wolf and moose is highly aim of their study was to see how various predator.

For the eight territories where we performed studies of wolf predation during two or three winters, we used the same estimate of prey density for all study years. The estimates of intra-territorial prey population densities at kill sites were derived from interpolation of data from the systematically distributed pellet count survey, using the Thiessen polygon method [ 3649 ].

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Prey density estimates included in the model correspond to the interpolated estimate at each kill site. Kill sites outside of the pellet count survey area were excluded from the analysis. For most data, snow depth included in analyses corresponded to the snow depth recorded at meteorological stations at the date of each kill.

prey and predator relationship in scandinavia

To estimate the snow depth for kill dates where no snow depth data was available generally measured on a daily basis but for some stations only twice per month we calculated the mean of the last measure before and the first measure after the actual date of kill. When snow measures were no longer available during a winter after the kill date, we assumed a zero snow depth.

Inter-territorial differences in prey preference To evaluate the preference of a certain prey over another at the population level inter-territorial we applied the Jacobs Index of Food Selection [ 52 ] to the data set using each wolf territory as one observational unit.

Prey availability in the territory was equal to the total number of prey as calculated from a combination of prey population density and the size of the wolf territory. The occurrence of a certain prey type in the diet was based on the total number of verified moose and roe deer killed in the same territory during the study period.

This index provides a symmetrical scale from -1 to 0 for avoidance and from 0 to 1 for preference.

Prey Selection of Scandinavian Wolves: Single Large or Several Small?

Values around zero show a neutral prey selection and we considered values from In addition, we used logistic regression to investigate the relationship between the proportion of roe deer in wolf-killed ungulates and; 1 the proportion of roe deer in the estimated availability of ungulates within the wolf territory; 2 roe deer density, and; 3 moose density. Because the data on roe deer densities at the territory level was skewed right, this variable was log-transformed.

In one of the territories Tenskogroe deer were not detected in the pellet count, even though roe deer killed by wolves were recorded there. As roe deer apparently had been present, we assigned the lowest roe deer density registered in any other territory to this territory 0.

In all models, we included pack size as a categorical variable with two classes, i. We weighted the observations with the length number of days of each study period. Definitions of terms of prey selection We defined prey selection as the process where a predator selects different types of prey without reference to the abundance of particular types of prey available whereas prey preference was defined as when a predator selects prey types disproportionately to its abundance in the environment [ 54 ].

Prey switching according to Murdoch [ 1 ] occurs when the number of attacks on a prey species is disproportionally large at high prey abundance relative to other prey species and disproportionally small when the species is relatively rare whereas prey vulnerability results from a combination of capture efficiency and profitability relative to risk [ 12 ]. The fitting of a Generalised Linear Mixed Model GLMM allows for the inclusion of multiple predictor variables that may affect the prey selection of wolves.

Once the predator has captured the prey, it has to handle it: Some catfish such as the Ictaluridae have spines on the back dorsal and belly pectoral which lock in the erect position; as the catfish thrashes about when captured, these could pierce the predator's mouth, possibly fatally.

Some fish-eating birds like the osprey avoid the danger of spines by tearing up their prey before eating it. Cooperative hunting In social predation, a group of predators cooperates to kill prey. This makes it possible to kill creatures larger than those they could overpower singly; for example, hyenasand wolves collaborate to catch and kill herbivores as large as buffalo, and lions even hunt elephants.

Lynx Body Size in Norway is Related to its Main Prey (Roe Deer) Density, Climate, and Latitude

For example, when mixed flocks of birds forage, the birds in front flush out insects that are caught by the birds behind. Spinner dolphins form a circle around a school of fish and move inwards, concentrating the fish by a factor of Predators of different species sometimes cooperate to catch prey.

In coral reefswhen fish such as the grouper and coral trout spot prey that is inaccessible to them, they signal to giant moray eelsNapoleon wrasses or octopuses.

These predators are able to access small crevices and flush out the prey. Solitary predators have more chance of eating what they catch, at the price of increased expenditure of energy to catch it, and increased risk that the prey will escape. These include speed, agility, stealth, sharp senses, claws, teeth, filters, and suitable digestive systems. Many predators have acute hearing, and some such as echolocating bats hunt exclusively by active or passive use of sound.

Some predators such as snakes and fish-eating birds like herons and cormorants swallow their prey whole; some snakes can unhinge their jaws to allow them to swallow large prey, while fish-eating birds have long spear-like beaks that they use to stab and grip fast-moving and slippery prey. Lions can attack much larger prey, including elephants, but do so much less often. Predators are often highly specialized in their diet and hunting behaviour; for example, the Eurasian lynx only hunts small ungulates.

When prey have a clumped uneven distribution, the optimal strategy for the predator is predicted to be more specialized as the prey are more conspicuous and can be found more quickly; [78] this appears to be correct for predators of immobile prey, but is doubtful with mobile prey. This has led to a correlation between the size of predators and their prey. Size may also act as a refuge for large prey.

Lynx Body Size in Norway is Related to its Main Prey (Roe Deer) Density, Climate, and Latitude

For example, adult elephants are relatively safe from predation by lions, but juveniles are vulnerable. Members of the cat family such as the snow leopard treeless highlandstiger grassy plains, reed swampsocelot forestfishing cat waterside thicketsand lion open plains are camouflaged with coloration and disruptive patterns suiting their habitats. Female Photuris firefliesfor example, copy the light signals of other species, thereby attracting male fireflies, which they capture and eat.

prey and predator relationship in scandinavia

Venom and Evolution of snake venom Many smaller predators such as the box jellyfish use venom to subdue their prey, [86] and venom can also aid in digestion as is the case for rattlesnakes and some spiders. These changes are explained by the fact that its prey does not need to be subdued.

Antipredator adaptation To counter predation, prey have a great variety of defences. They can try to avoid detection.