Evaluating vegetation effects on animal demographics: the role of plant phenology and sampling bias

Gibson, Daniel D.; Blomberg, Erik J.; Sedinger, James S.

doi:10.1002/ece3.2148

Cited by 46 publications

(76 citation statements)

References 45 publications

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“…Although no other lesser prairie‐chicken study has reported this threshold relationship, it is consistent with other grouse studies (Wiebe and Martin , McNew et al ). Similarly, nest survival was maximized between 2.0 and 4.0 dm in a quadratic relationship with 75% visual obstruction where visual obstruction was a better predictor of nest survival than vegetation composition; however, this relationship may be biased high because we sampled nest vegetation within 3 days of assessing nest fate, allowing vegetation to grow taller surrounding successful nests (Gibson et al , Smith et al ). Our findings are consistent with those from greater prairie‐chicken ( T. cupido ) research; however, greater prairie‐chicken peak nest survival occurred at a greater visual obstruction, likely because of greater vegetation growth resulting from increased precipitation relative to lesser prairie‐chicken range (McNew et al ).…”

Section: Discussionmentioning

confidence: 99%

Factors influencing nesting ecology of lesser prairie‐chickens

et al. 2018

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Lesser prairie‐chicken (Tympanuchus pallidicinctus) populations have declined since the 1980s. Understanding factors influencing nest‐site selection and nest survival are important for conservation and management of lesser prairie‐chicken populations. However, >75% of the extant population is in the northern extent of the range where data on breeding season ecology are lacking. We tested factors influencing fine‐scale and regional nest‐site selection and nest survival across the northern portion of the lesser prairie‐chicken range. We trapped and affixed satellite global positioning system and very high frequency transmitters to female lesser prairie‐chickens (n = 307) in south‐central and western Kansas and eastern Colorado, USA. We located and monitored 257 lesser prairie‐chicken nests from 2013 to 2016. We evaluated nest‐site selection and nest survival in comparison to vegetation composition and structure. Overall, nest‐site selection in relation to vegetation characteristics was similar across our study area. Lesser prairie‐chickens selected nest microsites with 75% visual obstruction 2.0–3.5 dm tall and 95.7% of all nests were in habitat with ≥1 dm and ≤4 dm visual obstruction. Nests were located in areas with 6–8% bare ground, on average, avoiding areas with greater percent cover of bare ground. The type of vegetation present was less important than cover of adequate height. Nest survival was maximized when 75% visual obstruction was 2.0–4.0 dm. Nest survival did not vary spatially or among years and generally increased as intensity of drought decreased throughout the study although not significantly. To provide nesting cover considering yearly variation in drought conditions, it is important to maintain residual cover by managing for structural heterogeneity of vegetation. Managing for structural heterogeneity could be accomplished by maintaining or strategically applying practices of the Conservation Reserve Program, using appropriate fire and grazing disturbances in native working grasslands, and establishing site‐specific monitoring of vegetation composition and structure. © 2018 The Wildlife Society.

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Section: Discussionmentioning

confidence: 99%

Factors influencing nesting ecology of lesser prairie‐chickens

et al. 2018

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“…Recent evidence has demonstrated that the positive association between grass height, a commonly used metric of herbaceous concealing cover among sage‐grouse nesting studies, and nest survival may be indicative of biased methods rather than a causal relationship (Gibson, Blomberg, et al., ; McConnell et al., ). Using both empirical and simulation approaches, it has been shown that measuring grass height at nests following nest fate (i.e., hatch or failure) produces inflated or even spurious statistical relationships between grass height and nest survival.…”

Section: Introductionmentioning

confidence: 99%

Phenology largely explains taller grass at successful nests in greater sage‐grouse

Smith

Tack

Doherty

et al. 2017

Ecology and Evolution

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Much interest lies in the identification of manageable habitat variables that affect key vital rates for species of concern. For ground‐nesting birds, vegetation surrounding the nest may play an important role in mediating nest success by providing concealment from predators. Height of grasses surrounding the nest is thought to be a driver of nest survival in greater sage‐grouse (Centrocercus urophasianus; sage‐grouse), a species that has experienced widespread population declines throughout their range. However, a growing body of the literature has found that widely used field methods can produce misleading inference on the relationship between grass height and nest success. Specifically, it has been demonstrated that measuring concealment following nest fate (failure or hatch) introduces a temporal bias whereby successful nests are measured later in the season, on average, than failed nests. This sampling bias can produce inference suggesting a positive effect of grass height on nest survival, though the relationship arises due to the confounding effect of plant phenology, not an effect on predation risk. To test the generality of this finding for sage‐grouse, we reanalyzed existing datasets comprising >800 sage‐grouse nests from three independent studies across the range where there was a positive relationship found between grass height and nest survival, including two using methods now known to be biased. Correcting for phenology produced equivocal relationships between grass height and sage‐grouse nest survival. Viewed in total, evidence for a ubiquitous biological effect of grass height on sage‐grouse nest success across time and space is lacking. In light of these findings, a reevaluation of land management guidelines emphasizing specific grass height targets to promote nest success may be merited.

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“…We used conditional logistic regression implemented via the clogit function in the package survival (Therneau ) to compare ptarmigan nest or brood use locations (case) to dependent random available locations (control). We were cognizant that vegetation can change over time (i.e., added growth or senescence), and when estimating covariate effects on nest survival, inconsistent timing of measurements can result in biased assessment of those effects on survival (Gibson et al , McConnell et al ). We did not measure vegetation at projected hatch dates as is suggested for nest survival analyses (Gibson et al , McConnell et al ), but we measured vegetation at dependent random sites immediately following measurements at the respective use site (typically within a day or 2 of use), directly comparing vegetation available to females within a given area at that given time (Prima et al ).…”

Section: Methodsmentioning

confidence: 99%

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

et al. 2019

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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.

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Evaluating vegetation effects on animal demographics: the role of plant phenology and sampling bias

Cited by 46 publications

References 45 publications

Factors influencing nesting ecology of lesser prairie‐chickens

Factors influencing nesting ecology of lesser prairie‐chickens

Phenology largely explains taller grass at successful nests in greater sage‐grouse

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

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