FINE SCALE HABITAT USE PATTERNS OF NORTHERN BOBWHITE IN DELAWARE USING AN AUTOMATED RADIO TELEMETRY NETWORK
Date
2024-05
Authors
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Publisher
University of Delaware
Abstract
Declines across the range of Northern bobwhite (Colinus viginianus) have
been noted since the early 1990’s but are recognized to extend back to the early 20th
century and perhaps beyond. Primary causes of these declines have been identified as
habitat loss and fragmentation, as well as invasion of non-native grasses and
increasingly industrial agricultural practices. Delaware is no stranger to these
bobwhite declines, with only a few remnant populations spread throughout the state.
One of these populations, located at Cedar Swamp Wildlife Area, has experienced
documented population increases from 9 to 68 coveys in the past decade. As such,
there is interest in the causes of this explosive increase in numbers. My goal was to
assess bobwhite habitat use patterns based on movement data from 13 radio tagged
adults using an automated radio telemetry system and historical data collected from
covey counts. I tracked tagged birds from 9 June 2023 to 15 April 2024. The
automated telemetry system consisted of 44 receiver nodes spread evenly over a 1
square kilometer area which reported to a central receiver tower. I trilaterated 69,580
locations for all tagged birds. Covey counts consisted of 18 fall covey counts from
2016 to 2020. I estimated habitat use and selection using a compositional analysis and
edge use analysis for both historical and telemetry data. Results indicated a preference
to remain <50 meters from forest and grassland edge in both data sets, and selection
for early successional herbaceous and woody habitat in the survey data. Telemetry
results showed selection of forest and grassland habitats. These results indicate habitat
selection largely consistent with previous literature, although forest use was
significantly higher than expected, indicating the importance of woody edge and cover
to healthy bobwhite populations.