Wed, Aug 17, 2022: 5:00 PM-6:30 PM
ESA Exhibit Hall
Background/Question/MethodsMigratory songbirds do not all arrive at breeding grounds simultaneously with conspecifics, and previous studies have demonstrated that earlier arriving males may preferentially settle higher quality habitat first. However, most studies of avian habitat selection are based on surveys that occur after the territory settlement period, thus failing to detect these potentially hidden habitat preferences. We hypothesized that monitoring site occupancy throughout territory settlement would reveal variation in songbird selection for different habitat treatments that would otherwise be obscured during a breeding season survey. We tested this hypothesis using 60 autonomous recorders placed within ~390 ha of paired fenced (to exclude deer; n = 30) and unfenced (n = 30) points in timber harvests in eastern temperate forest, collecting ~5,000 hrs of recordings from April 1-May 31, 2020. We examined naïve occupancy for three focal species: Black-and-white Warbler (Mniotilta varia; BAWW), Chestnut-sided Warbler (Setophaga pensylvanica; CSWA), and Field Sparrow (Spizella pusilla; FISP). These species were chosen because they represent a range of known habitat requirements and foraging styles. Analysis involved examining five minutes of audio per recorder per week for 8 weeks for these species’ songs and comparing the percent of sites of each treatment occupied week-to-week by each species.
Results/ConclusionsCSWA by week 6 was found at a substantially higher percentage of fenced sites than unfenced sites (35% difference), but by week 7 and 8, there was no substantial difference in percent occupancy (< 8% difference). This result supports our hypothesis that habitat preferences apparent during territory settlement may be cryptic during breeding surveys. However, occupancy of site types over time by FISP and BAWW provided equivocal support for our hypothesis as preferences and non-preferences were detectable for these species at week 8. In FISP, there was an evident preference for the unfenced sites both at week 1 and week 8 (24% and 23% difference, respectively). Interestingly, occupancy approached 100% for both site types around week 4, obscuring evidence of habitat preference during this time. In BAWW, there was no evident preference for habitat type with the difference in percent of each habitat type occupied never exceeding 9%. Thus, continuous monitoring throughout territory settlement could be a useful tool for identifying preferred habitat in some songbird species.
Results/ConclusionsCSWA by week 6 was found at a substantially higher percentage of fenced sites than unfenced sites (35% difference), but by week 7 and 8, there was no substantial difference in percent occupancy (< 8% difference). This result supports our hypothesis that habitat preferences apparent during territory settlement may be cryptic during breeding surveys. However, occupancy of site types over time by FISP and BAWW provided equivocal support for our hypothesis as preferences and non-preferences were detectable for these species at week 8. In FISP, there was an evident preference for the unfenced sites both at week 1 and week 8 (24% and 23% difference, respectively). Interestingly, occupancy approached 100% for both site types around week 4, obscuring evidence of habitat preference during this time. In BAWW, there was no evident preference for habitat type with the difference in percent of each habitat type occupied never exceeding 9%. Thus, continuous monitoring throughout territory settlement could be a useful tool for identifying preferred habitat in some songbird species.