Morphological change in Newfoundland caribou: Effects of abundance and climate

Mahoney, Shane P.; Weir, Jackie N.; Luther, J. Glenn; Schaefer, James A.; Morrison, Shawn F.

doi:10.7557/2.31.1.1917

Cited by 17 publications

(24 citation statements)

References 68 publications

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“…Skeletal size in ungulates is unaffected by ephemeral, seasonal changes in resource availability, but it is a particularly useful gauge of forage resources during development (Huot, 1988;Crête and Huot, 1993;Gerhart et al, 1997;Knott et al, 2005;Mahoney et al, 2011). In SHB, we found no significant differences in body size through time in the West.…”

Section: Discussioncontrasting

confidence: 42%

“…For migratory caribou, summer food may be limiting, as shown by both spatial and temporal comparisons. In Newfoundland, for example, declines in body size of males and females over time were correlated with population size at time of birth; decreases in stature were attributable to heightened, density-dependent competition for forage (Mahoney and Schaefer, 2002b;Mahoney et al, 2011). In Québec-Labrador, females in the George River herd were smaller than those in the adjacent Leaf River herd, a difference ascribed to insufficient and lower-quality forage (Crête and Huot, 1993).…”

Section: Discussionmentioning

confidence: 99%

“…A decline in the quality of the summer range can result in delayed arrival, reduced calf survival, and earlier departure from summering areas (Crête and Huot, 1993;Mahoney and Schaefer, 2002b;Couturier et al, 2009). Over decades, body size and population size can also reflect density-dependent fluctuations in available forage biomass (Crête and Huot, 1993;Mahoney and Schaefer, 2002b;Couturier et al, 2010;Mahoney et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

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Causes and Consequences of Broad-Scale Changes in the Distribution of Migratory Caribou (<i>Rangifer tarandus</i>) of Southern Hudson Bay

Newton¹,

Abraham²,

Schaefer³

et al. 2015

ARCTIC

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ABSTRACT. Understanding the factors driving changes in species distributions is fundamental to conservation, but for wide-ranging species this is often complicated by the need for broad-scale observations across space and time. In the last three decades, the location of summer concentrations of migratory caribou (Rangifer tarandus) in southern Hudson Bay (SHB), Canada, has shifted south and east as much as 500 km. We used long-term data (1987 -2011) to test two hypotheses that could explain the distribution shift: forage depletion and anthropogenic disturbance. Over time and space, we compared the body size of live-captured adult female caribou, dietary quality from fecal nitrogen in July, the location of VHF-and GPS-collared female caribou in July, distribution of all-terrain vehicle (ATV) tracks and caribou tracks in August, and the proximity of collared caribou to sections of the coast with higher ATV activity in spring and summer. The forage depletion hypothesis was supported by greater body size and dietary quality in caribou of the eastern portion of SHB than in western SHB animals in 2009 -11. The anthropogenic disturbance hypothesis was supported by the negative correlation of the distributions of ATV tracks and caribou tracks on the coast in 2010 and the fact that caribou avoided areas with ATV activity by 10 -14 km. In 1987, collared caribou were observed largely along the coast in western SHB in mid-July, while in 2009 -11, they were inland in western SHB and along the coast in eastern SHB. While these locations demonstrate a substantial change in summer distribution over three decades, we were unable to differentiate between forage depletion and anthropogenic disturbance as a single causal factor of the distribution shift.Key words: anthropogenic disturbance; body size; diet; distribution; fecal nitrogen; forage; migratory caribou; Hudson Bay; Rangifer tarandus; range shift RÉSUMÉ. La compréhension des facteurs qui influencent les changements caractérisant les distributions des espèces est fondamentale aux efforts de conservation, mais pour les espèces dont l'aire de distribution est étendue, ce principe est souvent compliqué par la nécessité de faire des observations à grande échelle, dans le temps et dans l'espace. Au cours des trois dernières décennies, l'emplacement des concentrations estivales du caribou migrateur (Rangifer tarandus) dans le sud de la baie d'Hudson (SBH), au Canada, s'est déplacé vers le sud et vers l'est dans une mesure de 500 km. Nous nous sommes appuyés sur des données de longue haleine pour mettre à l'épreuve deux hypothèses susceptibles d'expliquer ce changement en matière de distribution, soit l'appauvrissement du fourrage et la perturbation anthropique. Au fil du temps et de l'espace, nous avons comparé la taille du corps des caribous femelles adultes capturées vivantes, la qualité de leur alimentation à partir de l'azote fécal en juillet, l'emplacement des femelles portant un collier de type VHF ou GPS en juillet, la répartition des traces de véhicules tout terrain (VT...

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Section: Discussioncontrasting

confidence: 42%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Causes and Consequences of Broad-Scale Changes in the Distribution of Migratory Caribou (<i>Rangifer tarandus</i>) of Southern Hudson Bay

Newton¹,

Abraham²,

Schaefer³

et al. 2015

ARCTIC

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“…Biologists know that horn, antler, and pronghorn ( Antilocapra americana ) development is heavily influenced by nutrition in ungulates, including mountain sheep (Jorgenson et al , Coltman , Pigeon et al ), elk ( Cervus canadensis ), red deer ( Cervus elaphus ; Wang et al , Kruuk et al ), deer (French et al , Brown , Lockwood et al , Foley et al , Michel et al ), pronghorn (O'Gara , ), and caribou (Cronin et al , Mahoney et al ). Substandard and variable nutrition, caused by weather patterns, independent habitat degradation, or the density‐dependent effects of high population density, results in animals not expressing their genetic potential for horn or antler size.…”

Section: Obstacles To Evolutionary Change Through Trophy Selectionmentioning

confidence: 99%

Inefficiency of evolutionarily relevant selection in ungulate trophy hunting

Heffelfinger

2017

J Wildl Manag

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Differentially harvesting individual animals with specific traits has led some to argue that such selection can cause evolutionary change that may be detrimental to the species, especially if those traits are related positively to individual fitness. Most hunters are not selective in the type of animal they take, satisfied instead to harvest any legal animal. In a few exceptions, however, regulations may limit hunters to harvest animals of a minimum size or age regardless of their personal choice. Using information from a broad range of aquatic and terrestrial systems exposed to a myriad of potential and operational selective pressures, several authors have made expansive generalizations about selective harvest and its applicability to ungulates. Harvest-based selection can potentially be intensive enough to be relevant in an evolutionary sense, but phenotypic changes consistent with hunter selection are otherwise confounded with multiple environmental influences. Factors such as age, genetic contribution of females, nutrition, maternal effects, epigenetics, patterns of mating success, gene linkage, gene flow, refugia, date of birth, and other factors affecting selection interact with harvest to impede unidirectional evolution of a trait. The intensity of selection determines potential for evolutionary change in a meaningful temporal framework. Indeed, only under severe intensity, and strict selection on a trait, could human harvest prompt evolutionary changes in that trait. Broad generalizations across populations or ecological systems can yield erroneous extrapolations and inappropriate assumptions. Removal of males expressing a variety of horn or antler sizes, including some very large males, does not inevitably represent directional artificial selection unless the selective pressures are intensive enough to cause a unidirectional shift in allele frequencies that may act on some relevant life-history trait or process. Here I review the topic of harvest-based selection in male ungulates and discuss the inefficiency of trophy hunting in changing genetic expression of phenotype. Ó 2017 The Wildlife Society.

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“…These patterns have been well documented in Newfoundland where caribou populations have declined from approximately 94,000 to 32,000 animals between 1996 and 2013 (Bastille‐Rousseau et al , Weir et al ). A decrease in juvenile survival, largely due to predation by American black bears ( Ursus americanus ) and non‐native coyotes ( Canis latrans ), is the most likely proximate factor causing the population decline (Weir et al , Bastille‐Rousseau et al , Mahoney et al ), but the most likely ultimate factor is density‐dependent forage limitation (Mahoney et al , Weir et al ). Further, Weir et al () reported that unlike other woodland caribou populations, there is little evidence that the population decline was caused by decreased productivity (Boertje et al ) or as in western Canada (Hervieux et al ), apparent competition, the interaction in which species have adverse effects on one another by virtue of the beneficial effects that each has on a shared predator (Begon et al ).…”

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confidence: 99%

Manipulations of black bear and coyote affect caribou calf survival

et al. 2016

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The population of woodland caribou (Rangifer tarandus) in Newfoundland declined from approximately 94,000 to 32,000 animals between 1996 and 2013. Poor calf survival was the primary cause of the population decline, largely because of predation of newborn calves by American black bear (Ursus americanus) and the non‐native coyote (Canis latrans). This situation offered an opportunity to test the efficacy of preventative management options such as diversionary feeding and lethal removal of predators for improving calf survival. We monitored caribou calves (n = 536) in 4 calving areas (3 untreated, 1 treatment) for 2 years (2008–2009) followed by diversionary feeding of black bears and coyotes in 2010–2011 and lethal removal of coyotes in 2012–2013. We estimated calf survival for 70 days, the period calves and females remain on the calving grounds, and for 182 days, after which calves were considered recruited into the population. Calf survival was nearly constant over the 6‐year study period on the untreated areas. Calf survival was initially lower on the treatment area compared to the untreated areas but increased substantially on the treatment area during the lethal removal period, especially during the initial 70‐day period. Predation on calves by coyote decreased substantially during the lethal removal period. Diversionary feeding had little influence on survival rates. This study suggests that lethal removal of coyotes could be a viable management option for improving calf survival, but it is expensive and logistically challenging in remote field settings. © 2016 The Wildlife Society.

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Morphological change in Newfoundland caribou: Effects of abundance and climate

Cited by 17 publications

References 68 publications

Causes and Consequences of Broad-Scale Changes in the Distribution of Migratory Caribou (<i>Rangifer tarandus</i>) of Southern Hudson Bay

Causes and Consequences of Broad-Scale Changes in the Distribution of Migratory Caribou (<i>Rangifer tarandus</i>) of Southern Hudson Bay

Inefficiency of evolutionarily relevant selection in ungulate trophy hunting

Manipulations of black bear and coyote affect caribou calf survival

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