Monitoring breeding and migration of neotropical migratory birds at Point Loma, San Diego County, California, 5-year summary, 2011–15

Abstract

We operated a bird banding station on the Point Loma peninsula in western San Diego County, California, during spring and summer from 2011 to 2015. The station was established in 2010 as part of a long-term monitoring program for neotropical migratory birds during spring migration and for breeding birds as part of the Monitoring Avian Productivity and Survivorship (MAPS) program. During spring migration (April and May), 2011-15, we captured 1,760 individual birds of 54 species, 91 percent (1,595) of which were newly banded, fewer than 1 percent (3) of which were recaptures that were banded in previous years, and 9 percent (143 hummingbirds, 2 hawks, and 17 other birds) of which we released unbanded. We observed an additional 22 species that were not captured. Thirty-four individuals were captured more than once. Bird capture rate averaged 0.49 ± 0.07 captures per net-hour (range 0.41-0.56). Species richness per day averaged 6.87 ± 0.33. Cardellina pusilla (Wilson's warbler) was the most abundant spring migrant captured, followed by Empidonax difficilis (Pacific-slope flycatcher), Vireo gilvus (warbling vireo), Zonotrichia leucophrys (white-crowned sparrow), and Selasphorus rufus (rufous hummingbird). Captures of white-crowned sparrow decreased, and captures of Pacific-slope flycatcher increased, over the 5 years of our study. Fifty-six percent of known-sex individuals were male and 44 percent were female. The peak number of new species arriving per day ranged from April 1 (2013-six species) to April 16 (2012-five species). A significant correlation was determined between the number of migrants captured each day per net-hour and the density of echoes on the Next-Generation Radar (NEXRAD) images across all 5 years, and in each year except 2014. NEXRAD radar imagery appears to be a useful tool for detecting pulses in migration. Our results indicate that Point Loma provides stopover habitat during migration for 76 migratory species, including 20 species of conservation concern. Two of these species, Vireo bellii pusillus (least Bell's vireo) and Empidonax traillii (willow flycatcher) are listed as State and (or) federally threatened or endangered. Except for Archilochus alexandri (black-chinned hummingbird) and Setophaga occidentalis (hermit warbler), which arrived later during the migratory season in latter years of our study, median arrival dates for migratory species tended to be earlier each year or did not change across 5 years. Of the five most common migratory species, white-crowned sparrow and rufous hummingbird arrived earlier in latter years of the study, but Pacific-slope flycatcher, warbling vireo, and Wilson's warbler median arrival dates were variable and showed no trend. We captured 1,680 individuals of 66 species during the MAPS/breeding season (May through August) across the 5 years of our study, 72 percent (1,211) of which were newly banded, 10 percent (167) of which were recaptures, and 18 percent (302 hummingbirds and other birds that escaped prior to banding) of which we released unbanded. Bird c...

Monitoring breeding and migration of neotropical migratory birds at Naval Base Coronado, Remote Training Site, Warner Springs, San Diego County, California, 5-year summary, 2013–17

“…In general, however, bird capture rates during the breeding season at the Warner Springs banding station were low. The average capture rate at RTSWS (19 captures per 100 net-hours) was well below capture rates at other banding stations in other habitats in San Diego County, which ranged from 42 to 91 captures per 100 net-hours from 2013 to 2016 (Madden and others, 2014;Kus, 2014, 2015;Lynn and others, 2015;Hall and Kus, 2016;Lynn and Kus, 2017). Many of the bird species that we observed and did not capture, or captured only rarely, were species with behaviors that were not compatible with the standard mist-netting configuration.…”