Forest or meadow: the consequences of habitat for the condition of female arctic ground squirrels ( Urocitellus parryii plesius)
Dates
Year
2015
Citation
Werner, Jeffery R., Krebs, Charles J., Donker, Scott A., and Sheriff, Michael J., 2015, Forest or meadow: the consequences of habitat for the condition of female arctic ground squirrels ( Urocitellus parryii plesius): Canadian journal of zoology, v. 93, no. 10, p. 791-797.
Summary
Body condition of animals influences the likelihood of surviving harsh environmental conditions, successfully reproducing, and resisting disease. The sum of these individual components of fitness, in turn, have consequences for the growth and persistence of wildlife populations. Here we compared the body mass and condition of adult female arctic ground squirrels ( Urocitellus parryii plesius (Osgood, 1900)), an obligate hibernator, in source and sink habitats. We tested the hypothesis that adult females would be in poorer condition in the boreal forest than in adjacent meadows. We found that, during spring, postpartum females in forests weighed less (405 ± 7 vs. 437 ± 11 g; mean ± SE) and were in poorer condition (mean (±SE) residual [...]
Summary
Body condition of animals influences the likelihood of surviving harsh environmental conditions, successfully reproducing, and resisting disease. The sum of these individual components of fitness, in turn, have consequences for the growth and persistence of wildlife populations. Here we compared the body mass and condition of adult female arctic ground squirrels ( Urocitellus parryii plesius (Osgood, 1900)), an obligate hibernator, in source and sink habitats. We tested the hypothesis that adult females would be in poorer condition in the boreal forest than in adjacent meadows. We found that, during spring, postpartum females in forests weighed less (405 ± 7 vs. 437 ± 11 g; mean ± SE) and were in poorer condition (mean (±SE) residual of mass over structural size = -11.0 ± 10.2 vs. 20.5 ± 6.1 g) compared with females in meadow-source habitat. However, by the onset of entrance into hibernation in August, forest squirrels had reached parity with meadow squirrels and no difference was found in mass (519 ± 13 vs. 520 ± 15 g; mean ± SE) or condition (residual index = -0.01 ± 0.01 vs. 0.03 ± 0.01; mean ± SE). We suggest that for squirrels in formerly occupied boreal forests, ( i) poor spring body condition decreased reproductive success and ( ii) achieving compensatory growth, via increased foraging, comes at the costs of higher predation risk. These costs likely contributed to the recent local extinction of arctic ground squirrels in boreal forest habitat. (English) ABSTRACT FROM AUTHOR]; L'embonpoint des animaux influence la probabilité de survie dans des conditions ambiantes difficiles, le succès de reproduction et la résistance aux maladies. La somme de ces différentes composantes de l'aptitude a, quant à elle, des conséquences en ce qui concerne la croissance et la persistance des populations d'animaux sauvages. Nous comparons la masse corporelle et l'embonpoint de spermophiles arctiques ( Urocitellus parryii plesius (Osgood, 1900)) femelles adultes, une espèce hibernante inféodée, dans des habitats sources et puits. Nous vérifions l'hypothèse selon laquelle les femelles adultes présenteraient un moins bon embonpoint dans la forêt boréale que dans les baissières adjacentes. Nous avons constaté que, au printemps, les femelles post-partum dans les forêts présentaient une masse (405 ± 7 contre 437 ± 11 g; moyenne ± ET) et un embonpoint (résidue moyenne (±ET) de la masse sur la taille structurale = -11,0 ± 10,2 contre 20,5 ± 6,1 g) inférieurs à ceux des femelles dans les habitats sources de baissière. Cependant, au début de l'entrée en hibernation en août, les spermophiles des forêts avaient atteint la parité avec les spermophiles des baissières et aucune différence de masse (519 ± 13 contre 520 ± 15 g; moyenne ± ET), ni d'embonpoint n'était observée (indice résiduel = -0,01 ± 0,01 contre 0,03 ± 0,01; moyenne ± ET). Nous proposons que, pour les spermophiles dans des forêts boréales occupées antérieurement, ( i) le faible embonpoint printanier réduisait le succès de reproduction et ( ii) la compensation de la croissance par un approvisionnement accru vient au coût d'un risque de prédation accru. Ce coût a probablement contribué à la disparition locale récente de spermophiles arctiques dans des habitats de forêt boréale. Traduit par la Rédaction] (French) ABSTRACT FROM AUTHOR]; Copyright of Canadian Journal of Zoology is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
