Does Exurban Housing Development Affect the Physiological Condition of Forest-Breeding Songbirds? A Case Study of Ovenbirds (Seiurus aurocapillus) in the Largest Protected Area in the Contiguous United States

Abstract

Exurban development (low-density development in rural areas) can significantly alter wildlife community composition, but it is largely unknown whether it also affects wildlife at the individual level. We investigated individual-level impacts of exurban development in New York State's Adirondack Park by comparing the physiological condition of 62 male ovenbirds (Seiurus aurocapillus) breeding in forests with low-density housing development with those in contiguous forests. We used hematocrit (HCT) volume and plasma triglyceride (TRIG) levels to compare energetic condition, plasma uric acid (UA) and total plasma protein (TPP) levels to compare diet quality, and heterophil∶lymphocyte ratios (H∶L) to compare chronic stress. HCT was the only parameter to differ, with birds near houses exhibiting lower values. The comparable TRIG, UA, and TPP that we found between treatment types suggest that ovenbird food quality and availability are unaffected by exurban development in our study area. Similar H∶L suggests that homeowner activities do not significantly change chronic stressors faced by breeding male ovenbirds. We also found no difference in body mass, body size, or age ratio to indicate that habitats in either treatment type were in higher demand or more difficult to acquire. Although our results suggest that exurban development does not reduce habitat quality for male ovenbirds in a way that affects their condition, we caution that it may still ultimately reduce fitness by attracting synanthropic predators. Further work is needed to better understand the impacts of exurban development on wildlife at all levels and provide science-based information needed to meet conservation challenges in rapidly developing exurban areas.

Patterns in the physiological condition of three species of thrushes during autumn stopover near the south shore of Lake Ontario

“…Plasma was diluted to a factor of 3 or 4 using 0.9% saline solution, and plasma concentrations of triglyceride and uric acid were measured using colorimetric endpoint assays modified for micro-well plates (Seewagen et al 2015, Smith et al 2015). Plasma glucose was measured using the Wako Autokit Glucose microtiter procedure (Wako Diagnostics).…”

“…Leukocyte profiles were determined by examining each blood smear under 1,0003 oil immersion using a compound light microscope. Cells were counted until the total number of leukocytes reached 100, and then the ratio of heterophils to lymphocytes was calculated (Vleck et al 2000, Seewagen et al 2015, Oberkircher and Pagano 2018), hereinafter “H/L.” Parasites and abnormalities were also noted during the leukocyte count.…”