Dissertation Research: Allocation of Parental Effort in the Brown Thrasher--Effects of Predation Risk and Food Availability

9520335齐默尔曼许多研究表明，限制鸟类繁殖成功的两个最重要的因素是巢穴捕食和食物供应。最近有人提出，这两个因素的综合影响可能会通过父母分配给觅食雏鸟的时间和保护巢不受捕食者侵袭的时间之间的冲突来限制筑巢成功。在食物供应增加的地区筑巢的鸟类应该能够投入更多的时间来保护雏鸟免受捕食者的伤害，因此减少了对鸟巢的捕食。此外，在捕食者数量减少的地区筑巢的鸟类应该能够分配更多的时间用于觅食雏鸟，因此通过更大的雏鸟数量和生存能力来增加繁殖成功。这项研究将通过同时控制食物供应和捕食风险，在褐丝雀种群中测试这些时间分配假说。将对筑巢成功进行监测，并进行行为观察，以确定在食物供应增加、捕食风险降低或两者兼而有之的地区筑巢时，父母如何分配时间用于觅食和守护行为。这项研究将加深我们对影响鸟类觅食策略和决定筑巢成功的因素的理解。考虑到最近许多鸟类的数量下降，这一结果也可能有助于保护生物多样性的努力。

9520335 Zimmerman Many studies suggest that the two most important factors limiting the reproductive success of birds are nest predation and food supply. It has recently been proposed that the combined effects of these two factors may act to limit nesting success through a conflict between the time parents allocate to foraging for nestlings and time needed to guard the nest from predators. Birds nesting in territories with an increased food supply should be able to devote more time toward guarding the nestlings from predators and therefore experience reduced levels of nest predation. In addition, birds nesting in areas with reduced predator abundance should be able to allocate more time toward foraging for nestlings and therefore increase reproductive success through greater fledgling mass and survivability. This research will test these time allocation hypotheses in a population of brown thrashers by simultaneously manipulating food supply and predation risk. Nesting success will be monitored and behavioral observations will be conducted to determine how parents allocate time to foraging and guarding behaviors when nesting in areas of increased food supply, reduced predation risk, or both. This research will enhance our understanding of the factors that shape avian foraging strategies and determine nesting success. Given the recent population decline in many bird species, the results may also contribute to attempts to conserve biodiversity.