BOUGHTON, R.K.*; BOWMAN, R; KEARNS, L; SCHOECH, S.J; Univ. of Memphis; Archbold Biological Station; Archbold Biological Station; Univ. of Memphis: Variation between suburban and wildland populations in nestling immune response of Florida Scrub-Jays Aphelocoma coerulescens

In past years, a suburban population of Florida Scrub-Jays has produced fewer fledglings and fledglings of lighter mass per breeding pair than a nearby wildland population. Suburban young may be in poor condition relative to wildland young because their diet includes anthropogenic foods, which may be of lower quality than natural foods. Although brood sizes at hatching are similar at both sites, if the quality of food available for rearing young is lower in the suburbs, the optimal brood size may be smaller than the mean brood size, thus affecting the physiological condition of suburban birds in larger broods. We hypothesized that the specific response of nestlings to an immunological mitogen would differ by site and brood size. We used a phytohemagglutinin (PHA) assay to estimate cell-mediated immune response as an index of nestling physiological condition. We measured PHA immune responses during the 2004 and 2005 breeding seasons in 287 nestlings from 108 broods (39 suburbs, 69 wildlands) ranging from 1-5 nestlings. Immune response varied among brood sizes and between suburbs and wildlands. Nestlings in broods of 1 or 2 tended to have a lower immune response in wildlands than in the suburbs; however, immune response did not differ statistically in broods of 1-3 nestlings between the sites. The immune response of nestlings in broods of 4 was significantly lower in the suburbs than in the wildlands. This supports our hypothesis that the physiological condition of suburban nestlings is reduced in larger broods, likely due to improper anthropogenic foods and possibly reduced availability of natural nestling food resources to birds in the suburban site.