Data from: Forest structure provides the income for reproductive success in a southern population of Canada lynx

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.

探究繁殖成功率的内在与外在驱动因素，是推动动物生态学发展、划定关键栖息地的核心议题。遗憾的是，当前多数针对繁殖成功率驱动因素的研究，均偏向特定类群的生物（例如集群鸟类、大型植食动物、资本繁育者（capital breeder））。受保育关注的独居、领域性长寿食肉目哺乳动物，本是探究繁殖成功率内在与外在驱动因素的绝佳研究对象，但相关研究却极少受到关注。本研究依托分布范围南部边缘区域的加拿大猞猁（Lynx canadensis）数据集，旨在探究独居食肉动物的繁殖成功率是否符合资本繁育（capital breeding）或收入繁育（income breeding）策略。我们通过无线电标记追踪了36只雌性加拿大猞猁，累计监测时长达98个猞猁年。本研究评估了核心区域内的母体特征，以及基于森林结构表征的食物供应指数，如何影响体况与繁殖成功率的变异。我们将体况定义为体重与体长的比值，将繁殖成功率定义为雌性个体在特定繁殖季是否产下幼崽窝。与生活史理论相符，我们发现母体年龄对体况与繁殖成功率存在正向影响。与资本繁育策略的预测相悖，我们未观察到妊娠前体况对加拿大猞猁繁殖成功率存在影响。但我们证实，森林结构对加拿大猞猁的繁殖成功率存在统计学意义上的影响，这符合收入繁育策略的预测。与高繁殖成功率相关的森林特征包括：（1）丰富且连通性良好的成熟林；（2）中等占比的小径级更新林。这些特征能够为猞猁提供充足、时间上稳定且易于获取的猎物资源（即雪兔；Lepus americanus），同时印证了调控加拿大猞猁种群的上行调控机制。综合来看，本研究结果表明，栖息于其分布范围南部边缘的猞猁采用收入繁育策略，而森林结构为其成功繁殖提供了重要的资源补给。从更广泛的层面而言，本研究的发现深化了我们对食肉目动物生态学的认知，同时为结合长期野外研究与生态学理论以推动景观管理提供了重要范例。