Life and death in the fast lane: Demographic consequences of road mortality in the Florida Scrub-Jay

We examined the demographic consequences of road mortality in the cooperati vely breeding Florida Scrub-Jay (Aphelocoma coerulescens), a threatened spe cies restricted to the oak scrub of peninsular Florida. Between May 1986 an d July 1995 we monitored the survival and reproductive success of a color-b anded population of jays along a two-lane highway at Archbold Biological St ation. Annual mortality of breeding adults was 0.38 on road territories, si gnificantly higher than the rate of 0.23 for breeders on nonroad territorie s. High mortality on road territories appeared to be a direct result of aut omobile traffic per se and not a consequence of road-induced changes in hab itat characteristics. Mortality was especially high for immigrants without previous experience living along the road: in their first two years as bree ders on road territories, naive immigrants experienced annual mortality of 0.50 and 0.45. From year 3 onward, however, annual mortality dropped to 0.2 9, not significantly different from the rate for birds on nonroad territori es. This experience-dependent decline in road mortality could be caused eit her by surviving jays learning to avoid automobiles or by selective mortali ty operating through time (demographic heterogeneity). Proximity to the roa d had no effect on nesting success beyond its indirect effects on breeder e xperience and group size. Because the mortality of 30- to 90-day-old fledgl ings was significantly higher on road territories than on nonroad territori es, however, breeder mortality greatly exceeded production of yearlings on road territories. Roadside territories therefore are sinks that can maintai n populations of Florida Scrub-Jays only via immigration. Because Florida S crub-Jays do not avoid roadside habitats and may even be attracted to them, road mortality presents a difficult challenge for the management and conse rvation of this threatened and declining species.