Influence of Mist-netting Intensity on Demographic Investigations of Avian Populations
Ballard G, Geupel GR, Nur N. 2004. Influence of Mist-netting Intensity on Demographic Investigations of Avian Populations. Studies in Avian Biology. (29):21-27
An article comparing capture rates in two arrays of mist nets operated with different protocols in order to examine whether more intensive mist-netting effort leads to more accurate estimates of population size, productivity, and survivorship. We evaluated capture rates of juvenile and adult passerines, comparing two different netting regimes on the same study plot at the Palomarin Field Station, Point Reyes National Seashore, California. One set of nets was run approximately 5X as often as the other during the breeding season. For four resident species breeding in the immediate vicinity of the nets, results were compared to direct measures of productivity and breeding density as determined from nest monitoring, color banding of nestlings, and known densities of adults from spot-mapping censuses of color-banded individuals. Nets run 6 days/week captured an average of 42% of the Song Sparrows breeding within 100m of the nets, whereas nets run 1 day/week averaged 10% Capture rates of adult Wrentits did not differ significantly between netting regimes. Nets run with higher frequency detected direction of change in productivity in Song Sparrows accurately, whereas nets run with lower frequency did not. The reverse was true for Wrentits, though Wrentit fledglings were twice as likely to be caught in the higher frequency nets. Distance from nests to net also influenced juvenile capture probability. Results indicate the importance of using standardized netting protocol, and show that demographic indices based on mist netting should not be directly compared among species. Optimal netting frequency to attain study goals should be evaluated separately for each species. We caution investigators from drawing conclusions regarding songbird population size and demography based on mist-netting data alone.
- Type
- Journal Article
- Authors
- Ballard, Grant; Geupel, Geoffrey; Nur, Nadav
- Units
- PORE
- Keywords
- capture probability, Chamaea fasciata, demographic monitoring, Melospiza melodia, Mist Netting, Passerine, Population Size, Sampling Effort, Song Sparrow, Spot Mapping, Wrentit