Wolf kill rates across winter in a low-density moose system in Alaska

Abstract. Across much of the range of woodland caribou (Rangifer tarandus caribou), predator-prey dynamics have changed as a result of large-scale industrial development. Land clearing and associated early-successional forests have resulted in a greater density and distribution of moose (Alces alces), deer (Odocoileus spp.), and their associated predators. This process of apparent competition has resulted in increased predation on woodland caribou. We employed a combination of field and statistical methods to better understand the distribution and interactions of wolves (Canis lupus) and caribou across a region with high levels of industrial development. We used count models to investigate the frequency of wolf occurrence relative to landcover types, disturbance features, and caribou habitat. As predicted, the co-occurrence between caribou and wolves was rare. Similarly, the remains of caribou were identified at a small proportion of the sites where wolves killed large prey. Caribou occurred at low densities across the study area, and thus, wolves likely pursued other more abundant deer species. Encounters between wolves and caribou habitat was most likely to occur in the low-elevation boreal forest and areas closer to and with higher densities of forestry cutblocks. Our results highlight the importance of understanding the spatial dynamics of multi-species interactions when developing recovery strategies for threatened and endangered species.

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“…Also, numerous past works have validated the clustering of wolf locations, and by extension occupancy, at kill sites (e.g., Lake et al. ).…”

Section: Methodsmentioning

confidence: 99%

Evaluating the influence of anthropogenic landscape change on wolf distribution: implications for woodland caribou

2016

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“…Density in a 2010 survey was 0.11 moose/km 2 (Lake et al, 2013). This density corresponded to an ungulate biomass index of 0.66 UBI/km 2 , which reflected a conversion of moose density•6 (Fuller et al, 2003).…”

Section: Study Areamentioning

confidence: 99%

“…The major prey for wolves is moose, and moose densities had been low (< 0.2 moose/km 2 ) at least since the 1960s (Bentley, 1961;Gasaway et al, 1992;Bertram and Vivion, 2002;Caikoski, 2010;Lake et al, 2013). Density in a 2010 survey was 0.11 moose/km 2 (Lake et al, 2013).…”

Section: Study Areamentioning

confidence: 99%

“…The resulting ungulate biomass index was more representative of food availability to wolf populations. Minor prey species for wolves during winter were beaver (Castor canadensis) and snowshoe hare (Lepus americanus; Lake et al, 2013). During summer, salmon (Oncorhynchus spp.)…”

Section: Study Areamentioning

confidence: 99%

“…Wolves (Canis lupus) are efficient, coursing predators whose ability to maintain kill rates at the level needed to meet nutritional requirements allows them to persist down to low ungulate densities (0.11 moose/km 2 ) or biomass of food (0.66 ungulate biomass index, or UBI/km 2 ; Lake et al, 2013). Low ungulate biomass (< 4 UBI/km 2 ) can affect wolf populations in two ways.…”

Section: Introductionmentioning

confidence: 99%

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Wolf (<i>Canis lupus</i>) Winter Density and Territory Size in a Low Biomass Moose (<i>Alces alces</i>) System

Lake¹,

Caikoski²,

Bertram³

2015

ARCTIC

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ABSTRACT. We investigated the winter density and territory size of wolves (Canis lupus) on the Yukon Flats, Alaska, where moose (Alces alces) was the sole ungulate prey, occurring at a low density and representing a biomass of ungulate food lower than previously studied in North America. Using locations (GPS coordinates) from collars deployed on seven wolves, we estimated territory sizes with adaptive kernel and minimum convex polygon methods. We then estimated wolf density from a population area defined by these territory sizes and counts of wolves in five marked packs. From November 2009 to April 2010, we obtained 6263 GPS locations. Pack size ranged from two to 10 wolves, with average size of 5.0 in November 2009 and 4.8 in March 2010. Average winter territory size for the five packs was 1433 km 2 with the 95% adaptive kernel method and 1608 km 2 with the minimum convex polygon method. Density (wolves/1000 km 2 ) was 3.6 in November and 3.4 in March with the 95% adaptive kernel method and 3.4 in November and 3.3 in March with the minimum convex polygon method. Territories were large and estimates produced by the two methods differed by 11%. Densities were low, and the two analysis methods yielded densities that differed from each other by 3% to 6%. Low wolf density corresponded with low biomass of ungulate food, suggesting that moose availability on the Yukon Flats likely limited wolf density.Key words: Alaska; biomass; density; GPS; moose (Alces alces); territory; wolf (Canis lupus) RÉSUMÉ. Nous avons étudié la densité hivernale et la taille du territoire du loup (Canis lupus) aux Yukon Flats, en Alaska, où l'orignal (Alces alces) était la seule proie ongulée. Il s'y trouvait en faible densité et représentait une biomasse de nourriture ongulée inférieure à celle étudiée ailleurs en Amérique du Nord. Grâce aux positions (coordonnées de GPS) prélevées à partir de colliers posés sur sept loups, nous avons estimé la taille des territoires au moyen de la méthode d'estimation adaptative à noyaux et de la méthode du polygone convexe minimal. Ensuite, nous avons estimé la densité du loup à partir d'une zone de population définie par la taille de ces territoires et par les dénombrements de loups de cinq meutes marquées. De novembre 2009 à avril 2010, nous avons obtenu 6 263 positions GPS. La taille des meutes variait de deux à dix loups, pour une taille moyenne de 5,0 loups en novembre 2009 et de 4,8 en mars 2010. La taille moyenne du territoire hivernal de cinq meutes était de 1 433 km 2 dans le cas de la méthode adaptative à noyaux de 95 % et de 1 608 km 2 dans le cas de la méthode du polygone convexe minimal. La densité (loups/1000 km 2 ) était de 3,6 en novembre et de 3,4 en mars avec la méthode adaptative à noyaux de 95 %, puis de 3,4 en novembre et de 3,3 en mars avec la méthode du polygone convexe minimal. Les territoires étaient vastes et les estimations obtenues à l'aide des deux méthodes différaient de 11 %. Les densités étaient faibles, et les deux méthodes d'analyse ont donné des densités qui différaient ...

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Efficacy of GPS cluster analysis for predicting carnivory sites of a wide‐ranging omnivore: the American black bear

et al. 2016

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Abstract. The capacity to describe and quantify predation by large carnivores expanded considerably with the advent of GPS technology. Analyzing clusters of GPS locations formed by carnivores facilitates the detection of predation events by identifying characteristics which distinguish predation sites. We present a performance assessment of GPS cluster analysis as applied to the predation and scavenging of an omnivore, the American black bear (Ursus americanus), on ungulate prey and carrion. Through field investigations of 6854 GPS locations from 24 individual bears, we identified 54 sites where black bears formed a cluster of locations while predating or scavenging elk (Cervus elaphus), mule deer (Odocoileus hemionus), or cattle (Bos spp.). We developed models for three data sets to predict whether a GPS cluster was formed at a carnivory site vs. a non-carnivory site (e.g., bed sites or non-ungulate foraging sites). Two full-season data sets contained GPS locations logged at either 3-h or 30-min intervals from April to November, and a third data set contained 30-min interval data from April through July corresponding to the calving period for elk. Longer fix intervals resulted in the detection of fewer carnivory sites. Clusters were more likely to be carnivory sites if they occurred in open or edge habitats, if they occurred in the early season, if the mean distance between all pairs of GPS locations within the cluster was less, and if the cluster endured for a longer period of time. Clusters were less likely to be carnivory sites if they were initiated in the morning or night compared to the day. The top models for each data set performed well and successfully predicted 71-96% of field-verified carnivory events, 55-75% of non-carnivory events, and 58-76% of clusters overall. Refinement of this method will benefit from further application across species and ecological systems.

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Wolf kill rates across winter in a low-density moose system in Alaska

Cited by 20 publications

References 48 publications

Evaluating the influence of anthropogenic landscape change on wolf distribution: implications for woodland caribou

Evaluating the influence of anthropogenic landscape change on wolf distribution: implications for woodland caribou

Wolf (<i>Canis lupus</i>) Winter Density and Territory Size in a Low Biomass Moose (<i>Alces alces</i>) System

Efficacy of GPS cluster analysis for predicting carnivory sites of a wide‐ranging omnivore: the American black bear

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