scholarly journals Calf/female ratio and population dynamics of wild forest reindeer in relation to wolf and moose abundances in a managed European ecosystem

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0259246
Author(s):  
Ilpo Kojola ◽  
Ville Hallikainen ◽  
Samuli Heikkinen ◽  
Jukka T. Forsman ◽  
Tuomas Kukko ◽  
...  
Keyword(s):  
Population Size ◽  
Prey Species ◽  
Apparent Competition ◽  
Alternative Prey ◽  
Wolf Population ◽  
Female Ratio ◽  
Competition Hypothesis ◽  
Alternative Prey Hypothesis ◽  
Reindeer Population ◽  
Eastern Finland

Background The alternative prey hypothesis describes the mechanism for apparent competition whereby the mortality of the secondary prey species increases (and population size decreases decreases) by the increased predation by the shared predator if the population size of the primary prey decreases. Apparent competition is a process where the abundance of two co-existing prey species are negatively associated because they share a mutual predator, which negatively affects the abundance of both prey Here, we examined whether alternative prey and/or apparent competition hypothesis can explain the population dynamics and reproductive output of the secondary prey, wild forest reindeer (Rangifer tarandus fennicus) in Finland, in a predator-prey community in which moose (Alces alces) is the primary prey and the wolf (Canis lupus) is the generalist predator. Methods We examined a 22-year time series (1996–2017) to determine how the population size and the calf/female ratio of wild forest reindeer in Eastern Finland were related to the abundances of wolf and moose. Only moose population size was regulated by hunting. Summer predation of wolves on reindeer focuses on calves. We used least squares regression (GLS) models (for handling autocorrelated error structures and resulting pseudo-R2s) and generalized linear mixed (GLMs) models (for avoidance of negative predictions) to determine the relationships between abundances. We performed linear and general linear models for the calf/female ratio of reindeer. Results and synthesis The trends in reindeer population size and moose abundance were almost identical: an increase during the first years and then a decrease until the last years of our study period. Wolf population size in turn did not show long-term trends. Change in reindeer population size between consecutive winters was related positively to the calf/female ratio. The calf/female ratio was negatively related to wolf population size, but the reindeer population size was related to the wolf population only when moose abundance was entered as another independent variable. The wolf population was not related to moose abundance even though it is likely to consist the majority of the prey biomass. Because reindeer and moose populations were positively associated, our results seemed to support the alternative prey hypothesis more than the apparent competition hypothesis. However, these two hypotheses are not mutually exclusive and the primary mechanism is difficult to distinguish as the system is heavily managed by moose hunting. The recovery of wild forest reindeer in eastern Finland probably requires ecosystem management involving both habitat restoration and control of species abundances.

scholarly journals Habitat selection when killing primary versus alternative prey species supports prey specialization in an apex predator

2020 ◽  
Author(s):  
B Cristescu ◽  
S Bose ◽  
LM Elbroch ◽  
ML Allen ◽  
Heiko Wittmer
Keyword(s):  
Habitat Selection ◽  
Prey Species ◽  
Puma Concolor ◽  
Apparent Competition ◽  
Selection Function ◽  
Alternative Prey ◽  
Odocoileus Hemionus Columbianus ◽  
Ecological Processes ◽  
Habitat Features ◽  
Selection Of

© 2019 The Zoological Society of London Many predators specialize on one or several prey species that they select from the range of potential prey. Predator specialization on primary versus alternative prey is driven in part by encounter rates with prey and a predator’s habitat selection. Although habitat selection changes with behavioural state, this has not been well-recognized in the resource selection function (RSF) literature to date, often because auxiliary data on the predator’s behavioural states (e.g. hunting) are absent. We monitored habitat selection of pumas Puma concolor in a multi-prey system in northern California, where pumas specialized on black-tailed deer Odocoileus hemionus columbianus. We employed multiple RSF analyses on different datasets to test the following three hypotheses: (1) Pumas utilize habitats in proportion to their availability; (2) Pumas select specific habitat features when killing black-tailed deer, their primary prey; (3) Pumas do not select distinct habitats from those identified under hypothesis 1 when killing alternative prey. We found that pumas in our study selected for specific habitats and habitat features in general, but that their selection was more pronounced when killing black-tailed deer. In summer, kill sites of deer were associated with rugged terrain, but gentle slopes and northerly aspects. In winter, pumas killed deer at low elevations, on gentle slopes and on northerly and westerly aspects. Overall, evidence suggested that pumas tracked their primary prey across seasonal migrations, which were short in distance but resulted in pronounced changes in elevation. When killing alternative prey, pumas showed little evidence of habitat selection, suggesting they may kill alternative prey opportunistically. Our results hold implications for how data should be partitioned when modelling baseline habitat selection of predators, hunting habitat selection and predation risk for prey species, as well as for how we model ecological processes such as apparent competition.

scholarly journals Habitat selection when killing primary versus alternative prey species supports prey specialization in an apex predator

2020 ◽  
Author(s):  
B Cristescu ◽  
S Bose ◽  
LM Elbroch ◽  
ML Allen ◽  
Heiko Wittmer
Keyword(s):  
Habitat Selection ◽  
Prey Species ◽  
Puma Concolor ◽  
Apparent Competition ◽  
Selection Function ◽  
Alternative Prey ◽  
Odocoileus Hemionus Columbianus ◽  
Ecological Processes ◽  
Habitat Features ◽  
Selection Of

© 2019 The Zoological Society of London Many predators specialize on one or several prey species that they select from the range of potential prey. Predator specialization on primary versus alternative prey is driven in part by encounter rates with prey and a predator’s habitat selection. Although habitat selection changes with behavioural state, this has not been well-recognized in the resource selection function (RSF) literature to date, often because auxiliary data on the predator’s behavioural states (e.g. hunting) are absent. We monitored habitat selection of pumas Puma concolor in a multi-prey system in northern California, where pumas specialized on black-tailed deer Odocoileus hemionus columbianus. We employed multiple RSF analyses on different datasets to test the following three hypotheses: (1) Pumas utilize habitats in proportion to their availability; (2) Pumas select specific habitat features when killing black-tailed deer, their primary prey; (3) Pumas do not select distinct habitats from those identified under hypothesis 1 when killing alternative prey. We found that pumas in our study selected for specific habitats and habitat features in general, but that their selection was more pronounced when killing black-tailed deer. In summer, kill sites of deer were associated with rugged terrain, but gentle slopes and northerly aspects. In winter, pumas killed deer at low elevations, on gentle slopes and on northerly and westerly aspects. Overall, evidence suggested that pumas tracked their primary prey across seasonal migrations, which were short in distance but resulted in pronounced changes in elevation. When killing alternative prey, pumas showed little evidence of habitat selection, suggesting they may kill alternative prey opportunistically. Our results hold implications for how data should be partitioned when modelling baseline habitat selection of predators, hunting habitat selection and predation risk for prey species, as well as for how we model ecological processes such as apparent competition.

scholarly journals Different alternative diets within two subgroups in a winter roost of long-eared owls

2019 ◽  
Vol 13 (1) ◽  
pp. 139-144
Author(s):  
Filip Tulis ◽  
Tomáš Veselovský ◽  
Simon Birrer
Keyword(s):  
Prey Species ◽  
Common Vole ◽  
Wood Mouse ◽  
Alternative Prey ◽  
The Common

Abstract In winter 2013/2014 a roost of long-eared owls in Bojnice Spa (central Slovakia) was formed by two subgroups situated 12 meters apart from each other. The diets of both subgroups and the direction of the owls’ departure from the roost were studied at monthly intervals. Owls of the Pinus-subgroup left the roost in a significantly different direction compared with the owls in the Picea-subgroup. The common vole was the most hunted prey in both subgroups. However, comparing the alternative prey of the two subgroups, the wood mouse and other mammals were found significantly more often in pellets of the Picea-sub-group, whereas birds were more frequent in pellets of the Pinus-subgroup. Our results suggest that the different prey hunted by the two subgroups may be a consequence of diverging hunting areas with different availability of alternative prey species.

scholarly journals Changes in life history and population size can explain the relative neutral diversity levels on X and autosomes in extant human populations

2020 ◽  
Vol 117 (33) ◽  
pp. 20063-20069
Author(s):  
Guy Amster ◽  
David A. Murphy ◽  
William R. Milligan ◽  
Guy Sella
Keyword(s):  
Life History ◽  
Population Size ◽  
Mutation Rates ◽  
Human Populations ◽  
Effective Population ◽  
Mutation Bias ◽  
Female Ratio ◽  
Generation Times ◽  
Population Sizes ◽  
Male Mutation Bias

In human populations, the relative levels of neutral diversity on the X and autosomes differ markedly from each other and from the naïve theoretical expectation of 3/4. Here we propose an explanation for these differences based on new theory about the effects of sex-specific life history and given pedigree-based estimates of the dependence of human mutation rates on sex and age. We demonstrate that life history effects, particularly longer generation times in males than in females, are expected to have had multiple effects on human X-to-autosome (X:A) diversity ratios, as a result of male-biased mutation rates, the equilibrium X:A ratio of effective population sizes, and the differential responses to changes in population size. We also show that the standard approach of using divergence between species to correct for male mutation bias results in biased estimates of X:A effective population size ratios. We obtain alternative estimates using pedigree-based estimates of the male mutation bias, which reveal that X:A ratios of effective population sizes are considerably greater than previously appreciated. Finally, we find that the joint effects of historical changes in life history and population size can explain the observed X:A diversity ratios in extant human populations. Our results suggest that ancestral human populations were highly polygynous, that non-African populations experienced a substantial reduction in polygyny and/or increase in the male-to-female ratio of generation times around the Out-of-Africa bottleneck, and that current diversity levels were affected by fairly recent changes in sex-specific life history.

The Use of Alpha-Chloralose for the Repeated Capture of Western Gray Kangaroos, Macropus-Fuliginosus

1986 ◽  
Vol 13 (4) ◽  
pp. 527 ◽  
Author(s):  
GW Arnold ◽  
D Steven ◽  
J Weeldenburg ◽  
OE Brown
Keyword(s):  
Population Size ◽  
Taste Aversion ◽  
Female Ratio ◽  
Dose Rates ◽  
Male Female Ratio ◽  
Growth Development ◽  
Population Mortality ◽  
Alpha Chloralose ◽  
Initial Capture ◽  
Time Dose

Alpha-chloralose was used for 9 years in a study of growth, development and population size of western grey kangaroos, Macropus fuliginosus. Grain and water at accustomed feeding and watering points were drugged at intervals, for one night at a time; dose rates varied from 1.9 to 2.7 gl-1 in the water, and from 12 to 18 g kg-1 in the food. Many individuals developed a taste aversion to the drug, so that the number captured decreased over successive drug-nights. The taste could not be masked in water, but was in food when the type of food was changed. In the year after their initial capture, 44% of females and 35% of males were recaptured. Some were repeatedly captured in subsequent years; others only at intervals of several years. Animals drugged first as young-at-foot or as juveniles were captured in subsequent years less often than those first caught as subadults or adults. The male : female ratio in the adults captured was higher than in the population. Mortality was 4.5% of 1165 animals captured; 27% of deaths being due to fox predation. Females wlth pouch young, captured several times in a year, lost 8.8% of their young.

Managing wolves (Canis lupus) to recover threatened woodland caribou (Rangifer tarandus caribou) in Alberta

2014 ◽  
Vol 92 (12) ◽  
pp. 1029-1037 ◽  
Author(s):  
Dave Hervieux ◽  
Mark Hebblewhite ◽  
Dave Stepnisky ◽  
Michelle Bacon ◽  
Stan Boutin
Keyword(s):  
Canis Lupus ◽  
Rangifer Tarandus ◽  
Apparent Competition ◽  
Provincial Government ◽  
Population Increase ◽  
Rangifer Tarandus Caribou ◽  
Wolf Population ◽  
Woodland Caribou ◽  
Population Reduction ◽  
Reduction Program

Across Canada, woodland caribou (Rangifer tarandus caribou (Gmelin, 1788)) populations are declining because of human-induced changes to food webs that are resulting in apparent competition-induced increases in predator-caused caribou mortality. We tested the hypothesis that wolf (Canis lupus L., 1758) population reduction could reverse declines in a woodland caribou population following a BACI (before-after-control-impact) design conducted over a 12-year period in west-central Alberta, Canada. We monitored annual survival for 172 adult female caribou and calf recruitment from 2000 through 2012 and conducted a provincial government delivered wolf population reduction program annually during the winters of 2005–2006 to 2012 (inclusive) in an area centered on the Little Smoky range. Wolf removal translated to a 4.6% increase in mean population growth rate of the Little Smoky population mostly through improvements in calf recruitment. In contrast, the Red Rock Prairie Creek control population exhibited a 4.7% decline. Although the wolf population reduction program appeared to stabilize the Little Smoky population, it did not lead to population increase, however, with λ remaining approximately equal to 1. Therefore, we recommend, if required, predation management be combined with effective habitat conservation and long-term planning to effect the recovery of species, such as woodland caribou, which are declining as a result of habitat-mediated apparent competition.

scholarly journals Reindeer population size and trend on Edgeøya Svalbard

1998 ◽  
Vol 17 (1) ◽  
pp. 101-105
Author(s):  
Nils Are Øritsland
Keyword(s):  
Population Size ◽  
Reindeer Population
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