Fine‐Scale Habitat Selection by Breeding White‐Tailed Ptarmigan in Colorado

Abstract

Species distributions are influenced by climate and topography in alpine ecosystems, yet resource selection studies of alpine species are uncommon. Basic characteristics of habitats used by alpine‐endemic white‐tailed ptarmigan (Lagopus leucura) have been described to explain foraging behavior, morphology, and survival in many alpine regions; however, there is a lack of information about fine‐scale habitat selection for nesting and brood‐rearing, particularly in the southern extent of the species’ range. Few studies have tested whether nest and brood‐site selection by white‐tailed ptarmigan are influenced by fine‐scale components such as vegetation and arthropod communities. We assessed these fine‐scale habitat characteristics analyzing paired use‐available resource selection for nest (n = 61) and brood (n = 54) sites. We used conditional logistic regression for data collected in 2 alpine areas along the Front Range of Colorado, USA, during 2014 and 2015. We evaluated resource selection at larger (patch) and finer (nest site) scales. Nest‐site selection at the patch scale was best predicted by cover (%) of forage forbs, rock and gravel, and shrubs. Forage forb cover explained more variation in our top nest model at the patch scale when compared to models with specific vegetation species. Females placed their nests along elevational gradients but more so at lower elevations and selected for less graminoid cover at the nest‐site scale. Brood habitat selection at the patch level was influenced by cover (%) of rock and gravel and proximity to shrubs (m). Analysis of a subset of our brood data (n = 34) revealed females selected brood habitat that contained high arthropod abundance (e.g., Cicadellidae) over high vegetation cover, likely as a response to meet dietary requirements of chicks. Our results demonstrate how and where white‐tailed ptarmigan are currently selecting these different breeding sites in Colorado's alpine, giving us insight into consequences this alpine‐endemic bird may face if their breeding habitat is altered. © 2019 The Wildlife Society.

Estimates of Southern White-tailed Ptarmigan daily nest survival from multiple sites in the Southern Rocky Mountains of Colorado

“…In areas where White-tailed Ptarmigan sympatrically overlap with Rock Ptarmigan (L. muta), they occur at higher elevations with marginal cover and vegetation structure (Wilson and Martin 2012), but they experience higher nest success and number of hatched young than Rock Ptarmigan Martin 2010, 2012).At our study sites, we found a negative correlation between relative elevation and shrub cover (Pearson r = -0.481). Although shrub cover was only weakly related to daily nest survival, ptarmigan preferentially select shrub cover when it is available (Spear et al 2020), and previous studies have reported higher nest success with shrub concealment (Wiebe and Martin 1998b). On average, we also expect that higher elevations may be associated with lower-quality territories in terms of shrub food and concealment availability, which could have negative effects on the body condition of ptarmigan hens and subsequent fitness (Robb et al 1992).…”

Coping with unpredictable environments: fine-tune foraging microhabitat use in relation to prey availability in an alpine species

“…Foraging microhabitat selection has been largely investigated as a function of habitat characteristics and availability (Tsiakiris et al 2009 ; Belotti et al 2013 ; Eierman et al 2014 ; Spear et al 2020 ; Barras et al 2020 ; Korniluk et al 2021 ). Although it is generally assumed that a forager distribution occurs at the highest prey densities to maximise their intake rate (Holling 1959 ; Stephens and Krebs 1986; Zwarts and Wanink 1993 ; Wallace et al 2015 ; Roder et al 2020 ), there is evidence showing that the overlap between species occurrences and the distribution of key resources may be imperfect due to different constraints including habitat complexity (i.e., detectability; Martinez et al 2010 ; Müller et al 2012 ; Benoit-Bird et al 2013 ; Liu et al 2019 ), presence of predators (e.g., Brown 1988 ; Heithaus et al 2002 ; Clare et al 2023 ), density-dependent effects (Piersma 2012; DeRoy et al 2020 ), as well as limitation associated with the sampling methodology (e.g., Hunsicker et al 2011 ; Kuhn et al 2015 ).…”