Senescence, increased mortality that occurs among animals of advanced age, impacts behavior and ecology in many avian species. We investigated actuarial, reproductive, and behavioral senescence using capture, marking, and resighting data from a 26‐year study of common loons Gavia immer. Territorial residents of both sexes exhibited high annual survival (0.94) until their mid 20s, at which point survival fell to 0.76 and 0.77 in males and females, respectively. Sexual symmetry in actuarial senescence is somewhat surprising in this species, because males make a substantially greater investment in territory defense and chick‐rearing and because males engage in lethal contests for territory ownership. Survival of displaced breeders (0.80) was lower than that of territorial residents in both young and old individuals. Old males and females also experienced slightly higher annual probability of eviction (0.16 for males; 0.17 for females) than prime‐aged breeders (0.13 for both sexes), indicating senescence in territory defense. Prime‐aged males reclaimed territories at a high rate (0.49), in contrast to females of the same age (0.33). However, old males resettled with success (0.35) similar to old females (0.31), suggesting that males decline in competitive ability as they age. Nonetheless males, but not females, showed an apparent increase in breeding success over the entire lifetime, a possible indication that very old males make a terminal investment in reproductive output at the cost of survival.

Background Fire-adapted forests in western North America are experiencing rapid changes to fire regimes that are outside the range of historic norms. Some habitat-specialist species have been negatively impacted by increases in large, high-severity fire, yet, the responses of many species to fire, especially at longer time scales, remain ambiguous. We studied the response of a widely distributed species, the mountain quail (Oreortyx pictus), to wildfire across the Sierra Nevada of California, because its habitat selection patterns provided an opportunity to evaluate potentially contrasting responses among habitat specialists. Results We used passive acoustic monitoring across > 22,000 km2 of the Sierra Nevada and Bayesian hierarchical occupancy modeling to conduct the first study of the effects of habitat, fire severity, and time since fire (1–35 years) on the occupancy of a little-understood management indicator species, the mountain quail. Mountain quail responded positively to high-severity fire and neutrally to low-moderate-severity fire. Occupancy of quail peaked 6–10 years after high-severity fire and remained high even 11–35 years after an area burned at high severity. Conclusions Our work demonstrates that high-severity fire is strongly and positively related to mountain quail occupancy, which is a markedly different response than previously studied species that are also of management concern in the Sierra Nevada. Taken together, our results suggest that mountain quail may actually be “winners” in the face of altered fire regimes in the Sierra Nevada. Given the forecasted intensification of large, severe wildfires in many fire-adapted forests, understanding the ecology and nuanced fire responses of species beyond those that have been historically considered is an important and time-sensitive effort. The relationship between mountain quail and high-severity fire is a reminder that there will be both winners and losers as the dynamics of wildfire change in the era of climate change.

Many species show natal habitat preference induction (NHPI), a behavior in which young adults select habitats similar to those in which they were raised. However, we know little about how NHPI develops in natural systems. Here, we tested for NHPI in juvenile common loons (Gavia immer) that foraged on lakes in the vicinity of their natal lake after fledging. Juveniles visited lakes similar in pH to their natal lakes, and this significant effect persisted after controlling for spatial autocorrelation. On the other hand, juveniles showed no preference for foraging lakes of similar size to their natal one. When lakes were assigned to discrete classes based on size, depth, visibility, and trophic complexity, both juveniles from large lakes and small lakes preferred to visit large, trophically diverse lakes, which contained abundant food. Our results contrast with earlier findings, which show strict preference for lakes similar in size to the natal lake among young adults seeking to settle on a breeding lake. We suggest that NHPI is relaxed for juveniles, presumably because they select lakes that optimize short‐term survival and growth. By characterizing NHPI during a poorly studied life stage, this study illustrates that NHPI can take different forms at different life stages.

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