The Wilson Journal of Ornithology 124(2):310- 3 15, 2012 
THE EFFECT OF HABITAT EDGES ON NEST SURVIVAL OF 
SPRAGUE’S PIPITS 
STEPHANIE L. JONES'- 3 AND GARY C. WHITE 1 2 
ABSTRACT.—We explored the relationship between Sprague’s Pipit (Anthus sprugueii) nest (n = 125) survival and the 
distance from their nests to grassland edge and other linear features on Bowdoin National Wildlife Refuge in north-central 
Montana from 1997 to 2007. Specifically, we studied the effect of distance to roads (secondary paved road and tertian 
improved and unimproved dirt roads), an agriculture field, an active railroad right-of-way, and lacustrine shoreline on nest 
daily survival rate (DSR). The overall DSR was 0.95 ± 0.0057 (SE) with a 95% confidence interval of 0.94-0.%. We 
considered how models with distance thresholds (within 50. MX). 200, or 300 m) affected DSR while controlling for 
important eovariates. None of the distance models improved the model over the minimum A1C, model containing only non¬ 
distance covariates. There was no support for distance to any of the edges, including roads, having an effect on DSR relative 
to the minimum AIC,. model that contained three non-distance eovariates. Received 7 September 2011. Accepted 2i 
December 2011. 
Sprague’s Pipits (Anthus sprcigueii) are grass¬ 
land songbirds endemic to the northern Great 
Plains, breeding in south-central Canada anil 
north-central United Slates. Concern about threats 
to native mixed-grass prairie, coupled with 
observed population declines and range contrac¬ 
tions, has led to listing of the species as threatened 
in Canada (COSEWIC 2002) and proposed for 
listing in the United States (USDI 2010). 
Primary threats to Sprague's Pipit breeding 
populations include degradation, fragmentation, 
and loss of native mixed-grass prairies (COSEWIC 
2002, Environment Canada 2008, Jones 2010, 
USDI 2010). The level of threat that habitat 
fragmentation poses relative to the effects of 
habitat loss and degradation has been challenging 
to identify (Environment Canada 2008) with some 
studies suggesting Sprague's Pipits are area- 
sensitive (e.g.. Davis et al. 2006). Habitat frag¬ 
mentation may contribute to the decline of 
Sprague s Pipit populations through reduction in 
average patch size, increased isolation of habitat 
patches, and breaking the prairie into a mosaic of 
small native grasslands interspersed with non¬ 
grassland habitat patches (Environment Canada 
2008, Jones 2010). 
There are several mechanisms or factors that 
may influence how roads affect nest survivorship 
of grassland bird populations. These factors could 
1 U.S. Fish and Wildlife Service, P. O. Box 25486 DFC 
Denver, CO 80225, USA. 
Depaiimeni of Fish, Wildlife, and Conservation Biol- 
CO 80523 W USA' Cl>l ° rad ° S,a,C Umvcrsit >'- Fon Collins, 
’Corresponding author; e-mail; 
Stephanie_Jones@fws.gov 
include changes in food abundance and availabil¬ 
ity, attraction or repulsion of predators, increased 
noise and dust from traffic, spread of non-native 
vegetation in rights-of-way. enhanced develop¬ 
ment. and other disturbances radiating from these 
features (Fahrig and Rytwinski 2009). Similar 
effects may be associated with other linear 
anthropogenic and natural features including 
railroad rights-of-way, agriculture fields, fences, 
and natural edges including lakes and streams. 
The effects of the proximity to habitat edges and 
roads on the rate of nest depredation are not 
obvious with grassland studies showing both 
positive and negative effects (Lahti 2001). 
Fragmentation from linear features is considered 
to be a threat to Sprague’s Pipit abundance and 
demography (Environment Canada 2008); how¬ 
ever, the number of studies on this topic is limited 
and the results are mixed. For example, Koperand 
Schmiegelow (2006) found abundance of Spra¬ 
gue's Pipits was inversely correlated with distance 
to cropland and to water, and Sutter et al. (2000 
found Sprague's Pipits were significantly more 
abundant along two-track trails than along roads 
with adjacent ditches, fences, and non-name 
vegetation. However, Koper et al. (2009) reported 
abundance of Sprague’s Pipits in Alberta vvas 
not influenced by distance to roads. We analysed 
the effect of the distance to the nearest road 
(secondary paved road and tertiary dirt roads or 
trails), agriculture field, an active railroad rig.hr- 
of-way, and a lake shoreline on nest survivorship 
ot Sprague’s Pipits. We hypothesized there should 
be an inverse relationship between distance Iron' 
linear anthropogenic and natural features, and 
daily nest survival rates (DSR); however, we only 
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