ABSTRACT
Abstract. This chapter compares the phenology of forest trees, caterpillars, and Neotropical-Nearctic migrant songbirds during three successive spring seasons at Trelease Woods, a 24-ha deciduous forest fragment near Urbana, Illinois, in the United States, and describes a trophic cascade in years of phenological asynchrony. I show that the phenological patterns of budbreak and leaf emergence and the occurrence of canopy cater pillars varied significantly among springs, in accordance with variation in temperature accumulation. The timing of migration of migrant songbirds through the stopover, however, did not vary among years at the community or the species levels. As a result, activity by the three trophic levels was synchronized in 2002, but unsynchronized in 2001 and 2003. In the synchronized year, mean leaf area lost to folivory was 9.3% in both bur oak (Quercus
macrocarpa) and northern red oak (Q. rubra), but increased significantly to 20.5% in the year with least synchrony (2003). In the two years when black walnut (Juglans nigra) was included in the study, folivory increased from 1.8% in 2002 to 7.8% in 2003. Increases in folivory were likely an indirect result of trophic level asynchrony and are evidence of a trophic cascade. My findings raise concerns that more frequent early springs generated by climate change, with resulting trophic asynchrony, may affect the productivity and future composition of temperate deciduous forests, as well as the fitness of many NeotropicalNearctic birds.
