Friday, 16 March 2018

Forest structure provides the income for reproductive success in a southern population of Canada lynx.

Ecol Appl. 2018 Feb 19. doi: 10.1002/eap.1707. [Epub ahead of print] Kosterman MK1, Squires JR2, Holbrook JD3, Pletscher DH1, Hebblewhite M1. Author information 1 Wildlife Biology Program, Department of Ecosystem and Conservation Sciences, W.A. Franke College of Forestry and Conservation, University of Montana, 32 Campus Drive, Missoula, MT, 59812, USA. 2 United States Department of Agriculture Forest Service, Rocky Mountain Research Station, 800 E Beckwith, Missoula, MT, 59801, USA. 3 Department of Land Resources and Environmental Sciences, College of Agriculture, Montana State University P.O. Box 173120,, Bozeman, MT, 59717, USA. Abstract Understanding intrinsic and extrinsic drivers of reproductive success is central to advancing animal ecology and characterizing critical habitat. Unfortunately, much of the work examining drivers of reproductive success is biased toward particular groups of organisms (e.g., colonial birds, large herbivores, capital breeders). Long-lived mammalian carnivores that are of conservation concern, solitary, and territorial present an excellent situation to examine intrinsic and extrinsic drivers of reproductive success, yet they have received little attention. Here, we used a Canada lynx (Lynx canadensis) dataset, from the southern periphery of their range, to determine if reproductive success in a solitary carnivore was consistent with capital or income breeding. We radio-marked and monitored 36 female Canada lynx for 98 lynx years. We evaluated how maternal characteristics and indices of food supply (via forest structure) in core areas influenced variation in body condition and reproductive success. We characterized body condition as mass/length and reproductive success as whether a female produced a litter of kittens for a given breeding season. Consistent with life-history theory, we documented a positive effect of maternal age on body condition and reproductive success. In contrast to predictions of capital breeding, we observed no effect of pre-pregnancy body condition on reproductive success in Canada lynx. However, we demonstrated statistical effects of forest structure on reproductive success in Canada lynx, consistent with predictions of income breeding. The forest characteristics that defined high success included (1) abundant and connected mature forest and (2) intermediate amounts of small-diameter regenerating forest. These attributes are consistent with providing abundant, temporally stable, and accessible prey resources (i.e., snowshoe hares; Lepus americanus) for lynx and reinforce the bottom-up mechanisms influencing Canada lynx populations. Collectively, our results suggest that lynx on the southern range periphery exhibit an income breeding strategy and that forest structure supplies the income important for successful reproduction. More broadly, our insights advance the understanding of carnivore ecology and serve as an important example on integrating long-term field studies with ecological theory to advance landscape management. This article is protected by copyright. All rights reserved. KEYWORDS: Lepus americanus ; Lynx canadensis ; Habitat-fitness relationship; capital breeding; felids; habitat quality; income breeding; maternal effects; reproductive strategy; reproductive success PMID: 29457298 DOI: 10.1002/eap.1707