Influence of olfactory and visual cover on nest site selection and nest success for grassland‐nesting birds. Issue 16 (3rd July 2017)

• Record Type: Journal Article
• Authors: Fogarty, Dillon T.; Elmore, R. Dwayne; Fuhlendorf, Samuel D.; Loss, Scott R.
• Is Part Of: Ecology and evolution. Volume 7:Issue 16(2017:Sep.)
• Page Start: 6247
• Page End: 6258
• Publication Date: 2017-07-03
• Subjects: avian nest survival -- cover -- habitat selection -- nest site selection -- olfactory concealment -- olfactory predators -- precipitation -- weather; Ecology -- Periodicals; Evolution -- Periodicals; 577.05
• DOI: 10.1002/ece3.3195
• Languages: English
• ISSNs: 2045-7758

Abstract

Abstract: Habitat selection by animals is influenced by and mitigates the effects of predation and environmental extremes. For birds, nest site selection is crucial to offspring production because nests are exposed to extreme weather and predation pressure. Predators that forage using olfaction often dominate nest predator communities; therefore, factors that influence olfactory detection (e.g., airflow and weather variables, including turbulence and moisture) should influence nest site selection and survival. However, few studies have assessed the importance of olfactory cover for habitat selection and survival. We assessed whether ground‐nesting birds select nest sites based on visual and/or olfactory cover. Additionally, we assessed the importance of visual cover and airflow and weather variables associated with olfactory cover in influencing nest survival. In managed grasslands in Oklahoma, USA, we monitored nests of Northern Bobwhite ( Colinus virginianus ), Eastern Meadowlark ( Sturnella magna ), and Grasshopper Sparrow ( Ammodramus savannarum ) during 2015 and 2016. To assess nest site selection, we compared cover variables between nests and random points. To assess factors influencing nest survival, we used visual cover and olfactory‐related measurements (i.e., airflow and weather variables) to model daily nest survival. For nest site selection, nest sites had greater overhead visual cover than random points, but no other significant differences were found. Weather variables hypothesized to influence olfactory detection, specifically precipitation and relative humidity, were the best predictors of and were positively related to daily nest survival. Selection for overhead cover likely contributed to mitigation of thermal extremes and possibly reduced detectability of nests. For daily nest survival, we hypothesize that major nest predators focused on prey other than the monitored species' nests during high moisture conditions, thus increasing nest survival on these days. Our study highlights how mechanistic approaches to studying cover informs which dimensions are perceived and selected by animals and which dimensions confer fitness‐related benefits. Abstract : Weather‐related factors and predation are major sources of nest failure for birds. Nest site selection can be used to mitigate these adverse effects. We examined how visual cover variables and variables related to olfactory cover (e.g., airflow and moisture) influence nest survival and whether visual and olfactory cover is selected at nest sites of grassland‐nesting birds. Nests were selected with more overhead visual concealment, and nests were more likely to succeed during high moisture conditions (high humidity and precipitation events). We surmise that overhead cover was used to mitigate thermal extremes and that during high moisture conditions predators focused foraging attention to prey other than the monitored species' nests, thus increasing nest survival.