Influence of military training on breeding ecology of Bachman's sparrow

Abstract

Anthropogenic disturbance may cause birds to flush and relocate, abandon breeding sites, experience increased nest failure, or fledge fewer young. Ground‐based military activities are of particular concern for ground‐nesting birds because of the increased risk of nest destruction and trampling of vegetation. We investigated how different intensities of disturbance from ground‐based military training affected reproductive ecology of Bachman's sparrow (Peucaea aestivalis) from 2014–2016, on Fort Bragg Military Installation, North Carolina, USA. We designated 2 training intensity regimes and monitored sparrows at 6 observation areas, 3 in high‐intensity training areas (i.e., foot traffic every 1–3 days) and 3 in low‐intensity training (i.e., foot traffic <1 per month) areas. We compared seasonal productivity metrics and daily nest survival between training intensities. Additionally, we compared male sparrow relative abundance and micro‐habitat use between high‐ and low‐intensity training areas. We monitored 106 male territories and located 110 nests opportunistically and by tracking telemetered female sparrows. We used fixed‐radius point counts to estimate relative abundance in each observation area and measured vegetation composition and structure at a subset of 10 locations in each male territory. Seasonal productivity metrics, daily nest survival, relative abundance, and vegetation composition and structure at male locations did not differ between areas with high and low military training intensity. In 2015, 1 sparrow nest was trampled by military personnel, but ≥1 nestling force‐fledged and the nest was considered successful. Bachman's sparrow nesting ecology was not affected by intensity of ground‐based military training activity, likely because activity was sufficiently dispersed across the landscape, even in high‐intensity training areas. We recommend ground‐based training attempts to minimize ground vegetation destruction by dispersing large groups and traversing variable routes when in forested uplands. © 2018 The Wildlife Society.

Fledgling Bachman’s Sparrows in a longleaf pine ecosystem: survival, movements, and habitat selection

“…Many wildlife openings had previously been planted with species that provide forage for white‐tailed deer ( Odocoileus virginianus ), but were often left fallow for several years before planting again. Fort Bragg contains drop zones ( N = 9; mean = 250 ± 45 [SE] ha), artillery firing points ( N = 49; mean = 4.4 ± 0.4 [SE] ha), and wildlife openings ( N = 1283; mean = 0.31 ± 0.02 [SE] ha), all of which lacked nesting Bachman’s Sparrows (Fish et al 2019).…”

“…We also measured vegetation cover at 10 randomly selected locations of adult males attending fledglings, considered representative of habitat availability. We identified male locations while spot‐mapping breeding sparrows in a marked population from April to July 2014–2016 (Fish et al 2019). Using a 2‐m tall, 2.54‐cm wide Wiens pole (Wiens 1974), we recorded vegetation contacts anywhere on the pole, along two perpendicular 10‐m transects, centered over the locations of both fledglings and adult males (Brooks and Stouffer 2010, Fish et al 2019).…”

“…We identified male locations while spot‐mapping breeding sparrows in a marked population from April to July 2014–2016 (Fish et al 2019). Using a 2‐m tall, 2.54‐cm wide Wiens pole (Wiens 1974), we recorded vegetation contacts anywhere on the pole, along two perpendicular 10‐m transects, centered over the locations of both fledglings and adult males (Brooks and Stouffer 2010, Fish et al 2019). We classified vegetation contacts (hereafter, hits) as grass, forb, or woody (shrubs or regenerating trees).…”

“…Additionally, we recorded the presence or absence of bare ground cover immediately beneath each Wiens pole reading. We calculated percent grass, forb, and woody cover at each location by calculating the proportion of the 21 Wiens pole readings with ≥ 1 hit of each vegetation type (Fish et al 2018(Fish et al , 2019. We estimated percent bare ground cover by calculating the proportion of 21 Wiens poles readings classified as bare ground.…”