Geographic variation in avian life history traits and parental care behaviors
Life history traits, such as clutch size, egg size, renesting rates, developmental rates, adult survival, and parental care behaviors (incubation, brooding, feeding young), vary extensively in geographic space. This project focuses on understanding why life history strategies vary among species and among geographic regions. We measure these traits and behaviors for the first time for relatively large numbers of species across a series of geographic sites: Arizona (ongoing work since 1985), Argentina (ended 2000), South Africa (ended 2004), New Zealand and Tasmania, Venezuela (will end in 2008), and Borneo (new start in 2009).
Climate effects on a high elevation riparian ecosystem and bird community
A long-term (since 1985) study of a high elevation riparian ecosystem and bird community demonstrates climate effects on trophic interactions among plants, birds, and nest predation. Key deciduous plants and several bird species have declined strongly in abundance, with one previously common bird species (MacGillivray's Warbler) even going locally extinct. Large herbivores may interact with climate change to cause plant losses (see next project).
Long-term declines in plants, and many bird species that rely on these plants, may reflects of over-browsing by large herbivores, together with climate change (see above project). Herbivory and climate may interact in that drier years may yield lower plant propogation that make them more susceptible to browsing pressures. Large-scale (9 ha) exclosures will be erected on three sites in 2004 to examine the separate effects of herbivores versus climate.
The BBIRD program was initiated in 1992 to encourage standardized sampling protocols for studying breeding bird nesting successs and associated habitat. By accumulating comparable data in a single database allows comparisons of landscape effects on nest predation and parasitism, as well as providing information on variation in these parameters in time and space.
