Hooded Warbler
Ecoregional Scale Conservation Planning
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Made possible through a partnership with the National Wetlands Research Center


Chimney Swift (Chaetura pelagica)
Status:
Chimney swifts occur across most of North America east of the Rockies. Populations have declined in both the CH and WGCP over the last 40 years (2.6 and 1.1 percent per year); however, the high annual variability in this species abundance prevents detection of significant trends (Sauer and others 2005; Table 005 Table 005) . The species has a regional combined score of 16 and is a classified as needing management attention in the CH. However, in the WGCP, the chimney swift is only a planning and responsibility species with a regional combined score of 14 Table 001 (Table 001) .
chsw
Relative abundance of Chimney Swift, derived from Breeding Bird Survey data, 1994 - 2003.
 
image courtesy of www.whatbird.com
 

Natural History:
The chimney swift is a small long-distance migrant whose range expanded dramatically with European settlement and the increase in artificial nest structures (i.e., chimneys) that followed (Cink and Collins 2002). Prior to European settlement, the species was probably thinly distributed and relied on tree cavities for nesting. Nesting in trees is now rare (Graves 2004), and most nests and roosts are concentrated in urban areas (Cink and Collins 2002). The species is weakly territorial (typically 1 nest per cavity), and population declines may be due to loss of nest sites as large open chimneys become scarce. Home range sizes are largely unknown.

Model Description:

For a bird that occurs in such close association with humans, extraordinarily little data is available on chimney swift habitat preferences. We assumed habitat suitability for this species was mostly affected by the availability of nest and roost sites within the proper landscape context (i.e., open chimneys near foraging areas). To identify these locations, we estimated the proportion of foraging habitats in a 1 km buffer around each pixel of developed landcover. We assumed birds could travel 1 km from nesting-roosting areas to foraging habitats (defined as water, grassland, pasture-hay, recreational grasses, or forest landcover classes) and these habitats needed to be >1 ha to accommodate the aerial foraging maneuvers of this species. Because chimney swifts are semi-colonial, we also assumed that as foraging habitat increased in the 1 km buffer, developed pixels were increasingly isolated and would be of lower habitat suitability Table 055 (Table 055) . We used a quadratic curve Figure 030 (Figure 030) to quantify the relationship between landscape composition and chimney swift habitat suitability.

Verification and Validation
Chimney swifts occurred in all 88 subsections of the CH and WGCP. Spearman rank correlation identified a significant (P ≤ 0.001) positive relationship (r = 0.50) between average HSI score and mean BBS route abundance across subsections. Negative binomial regressions between these variables at the subsection and route scales indicated a positive relationship between HSI scores and abundance and an improvement of the HSI model over the null model for predicting chimney swift abundance.

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