As the climate changes, mismatches in phenology between predator and prey species may become more common. For example, many songbirds rely on short peaks in insect and fruit production at stopover sites during migration. Previous research indicates that migratory songbirds are able to modify their departure and arrival dates to some extent despite their reliance on more stable cues such as photoperiod and more stable endogenous factors. However, insect and plant phenology may shift more rapidly with changing climate, reducing foraging opportunities along migratory routes. To quantify changes in songbird arrival patterns at stopover sites during fall migration we analyzed forty years of banding data in nine passerine species commonly captured at banding stations in southwestern Michigan. Weather data revealed that the region has warmed by nearly 2° (C) over this timeframe. For each species, we assessed annual trends in arrival date and temperature at arrival. To determine whether arrival trends impacted stopover site function we also quantified trends in site use and morning mass gain. Arrival dates advanced significantly in three species, and were delayed significantly in three other species. However, air temperature at arrival increased significantly over time for all nine study species. Over the same time period, site use and the pattern of morning mass gain remained stable or increased for all species. Despite the changing climate and the resulting increase in temperature at arrival for migrants, our data indicate that these stopover locations continue to function as a refueling sites. Nonetheless, we must be wary of thresholds and ecological mismatches that may occur if warming trends continue.

The tick Ixodes brunneus Koch (Acari: Ixodidae) is reported for the first time in Michigan from two bird hosts at two locations in the lower peninsula. All stages of this tick exclusively feed on birds, and are primarily known from the southern U.S., although abundant records occur from northern states. The role of this species as a vector of pathogens is discussed.

Nearctic-neotropical passerines may spend up to one-third of the year in migration. Stopover sites have a critical role in providing migrant passerines with areas to rest and replenish fat stores. We characterized the stopover ecology of the Tennessee Warbler (Oreothlypis peregrina) at an inland site in Vicksburg, Michigan, using data from 4,607 warblers captured between 1990 and 2007. The recapture rate ranged from 1.6 to 12.1% annually and recaptured migrants averaged small but significant mass gains. Estimates of mass change using regression of mass on time of capture also suggested mass increases at this site. Recapture rate and mass gain estimated by regression varied significantly across the 18 years of study, although stopover length and mass change among recaptured individuals did not. Adult (after hatching year, AHY) warblers in active flight feather molt had an average lower mass and were four times more likely to be recaptured than non-molting adults. Over 95% of birds captured were hatching year (HY). The average condition and mass gains estimated by regression of BY warblers were lower than that of AHYs, but recapture rate, stopover length, and mass gains by recaptured individuals did not differ between the two age groups. The high number of captures and mass gains demonstrate the value of this site for fall migrant Tennessee Warblers. The annual differences in recapture rate and mass gains reported in this study suggest that several years of data may be needed to develop an accurate assessment of the typical use of a stopover site by migrants. Received 8 October 2008. Accepted 1 October 2012.