Testing the importance of nest concealment: does timing matter?

Rivera, Jorge H. Vega; Montaño, Irais Medina; Rappole, John H.; Cerda, Felipe Campos

doi:10.1111/j.1557-9263.2009.00234.x

Cited by 7 publications

(7 citation statements)

References 21 publications

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“…The timing of vegetation measurement and its impacts on interpretation of selective processes is well documented (Burhans & Thompson, ; Rivera et al. ). Burhans and Thompson () recommended measuring nest‐site vegetation when nest‐site selection occurs but acknowledge the risk of influencing nest fate with this approach.…”

Section: Discussionmentioning

confidence: 99%

“…Rivera et al. () found that measurements of vegetation structure in highly seasonal ecosystems could be delayed until the end of the reproductive cycle. We found decreased bias in all Late‐initiated scenarios which is likely a result of the relatively flat slope of the vegetation growth curve during the Late nesting season where differences in ACH are minimal between hatched and failed nests.…”

Section: Discussionmentioning

confidence: 99%

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Timing of nest vegetation measurement may obscure adaptive significance of nest‐site characteristics: A simulation study

McConnell

Monroe

Burger

et al. 2017

Ecology and Evolution

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Advances in understanding avian nesting ecology are hindered by a prevalent lack of agreement between nest‐site characteristics and fitness metrics such as nest success. We posit this is a result of inconsistent and improper timing of nest‐site vegetation measurements. Therefore, we evaluated how the timing of nest vegetation measurement influences the estimated effects of vegetation structure on nest survival. We simulated phenological changes in nest‐site vegetation growth over a typical nesting season and modeled how the timing of measuring that vegetation, relative to nest fate, creates bias in conclusions regarding its influence on nest survival. We modeled the bias associated with four methods of measuring nest‐site vegetation: Method 1—measuring at nest initiation, Method 2—measuring at nest termination regardless of fate, Method 3—measuring at nest termination for successful nests and at estimated completion for unsuccessful nests, and Method 4—measuring at nest termination regardless of fate while also accounting for initiation date. We quantified and compared bias for each method for varying simulated effects, ranked models for each method using AIC, and calculated the proportion of simulations in which each model (measurement method) was selected as the best model. Our results indicate that the risk of drawing an erroneous or spurious conclusion was present in all methods but greater with Method 2 which is the most common method reported in the literature. Methods 1 and 3 were similarly less biased. Method 4 provided no additional value as bias was similar to Method 2 for all scenarios. While Method 1 is seldom practical to collect in the field, Method 3 is logistically practical and minimizes inherent bias. Implementation of Method 3 will facilitate estimating the effect of nest‐site vegetation on survival, in the least biased way, and allow reliable conclusions to be drawn.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Timing of nest vegetation measurement may obscure adaptive significance of nest‐site characteristics: A simulation study

McConnell

Monroe

Burger

et al. 2017

Ecology and Evolution

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“…Concealment was not strongly correlated with measurement date (r = 0AE04, n = 209 natural-and experimental-nest site measurements collected 3 July-31 August, 2006August, -2007, so our measurements strictly captured spatial variation in nest concealment independent of shrub phenology. Given significant effects of phenology, concealment measurements may not represent sites as they were when selected by nesting birds or when depredated (Vega Rivera et al 2009). Nevertheless, our measurements should index relative concealment of sites selected by birds (nest sites) or available to them (random sites), assuming that phenology does not cause rank reversals (i.e.…”

Section: Nest-searching and Microhabitat Measurementsmentioning

confidence: 99%

How avian nest site selection responds to predation risk: testing an ‘adaptive peak hypothesis’

Latif

Heath

Rotenberry

2011

Journal of Animal Ecology

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Summary1. Nest predation limits avian fitness, so birds should favour nest sites that minimize predation risk. Nevertheless, preferred nest microhabitat features are often uncorrelated with apparent variation in predation rates. 2. This lack of congruence between theory-based expectation and empirical data may arise when birds already occupy 'adaptive peaks'. If birds nest exclusively in low-predation microhabitats, microhabitat and nest predation may no longer be correlated even though predation ultimately shaped microhabitat selection. 3. This 'adaptive peak hypothesis' was tested for a population of Yellow Warblers (Dendroica petechia) focusing on two nest microhabitat features: concealment and height. Experimental nests measured relative predation risk both within and outside the microhabitat range typically occupied by natural nests to examine whether nest site choices made by birds restricted our ability to detect microhabitat effects on predation. 4. Within the natural range (30-80% concealment, >75 cm height), microhabitat-predation relationships were weak and inconsistent, and similar for experimental and natural nests. Over an extended range, however, experimental predation rates were elevated in exposed sites (<30% concealed), indicating a concealment-related 'adaptive plateau'. 5. Clay egg bite data revealed a concealment effect on avian predators, and the abundance of one avian predator group correlated with nest concealment among years, suggesting these predators may cue birds to modulate nest concealment choices. 6. This study demonstrates how avian responses to predation pressure can obscure the adaptive significance of nest site selection, so predation influences may be more important than apparent from published data.

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“…This is not always straightforward. Consider the relationship between vegetation density and the risk of nest predation: measuring nest vegetation at the end of the breeding season could obscure that correlation, because conditions at the end of the season may not reflect vegetation density at the time the nest was actually discovered by a predator (Borgmann & Conway, 2015;Burhans & Thompson, 2001;Vega Rivera, Montaño, Rappole, & Cerda, 2009). An exception may be if vegetation growth was highly predictable over space and time, and measures of vegetation at different nests remained independent and did not converge.…”

Section: Introductionmentioning

confidence: 99%

Vegetation phenology and nest survival: Diagnosing heterogeneous effects through time

Ringelman

Skaggs

2019

Ecology and Evolution

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Birds should select nest sites that minimize predation risk, but understanding the influence of vegetation on nest survival has proven problematic. Specifically, the common practice of measuring vegetation on nest fate date can overestimate its effect on nest survival, simply because vegetation at hatched nests grows for a longer period of time than vegetation at nests that were depredated. Here, we sampled the literature to determine the prevalence of this bias in studies of duck breeding ecology. We then used survival data collected from ~2,800 duck nests to empirically evaluate evidence of bias in four different vegetation metrics: vegetation density measured when the nest was found, density when the nest was fated, and date‐corrected regression residuals of these two. We also diagnosed the magnitude of vegetation effects on nest survival by restricting our analysis to only nests which were fated contemporaneously (thereby removing potential bias in the timing of measurement). Finally, we examined whether systematic phenological differences exist between vegetation at hatched and depredated nests that have the potential to further obfuscate the relationship between vegetation and nest survival. We found evidence for a true‐positive effect of vegetation density on nest survival that appeared to be inflated when using raw vegetation measurements collected at fate date. However, taken in combination with the literature review, our results suggest that the majority of duck nesting studies have evaluated the role of vegetation on nest survival using a relatively less biased metric—vegetation density when the nest was found. Finally, we found that over the course of a nesting attempt, vegetation increased in density at successful nests, but decreased in density at depredated nests. As a consequence, duck researchers using vegetation data collected when the nest was found may actually be underestimating the magnitude of the effect. This seasonal change potentially points to an important new metric for understanding predation risk, but further experimental research is required to fully eliminate potential biases in the timing of vegetation measurements.

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Testing the importance of nest concealment: does timing matter?

Cited by 7 publications

References 21 publications

Timing of nest vegetation measurement may obscure adaptive significance of nest‐site characteristics: A simulation study

Timing of nest vegetation measurement may obscure adaptive significance of nest‐site characteristics: A simulation study

How avian nest site selection responds to predation risk: testing an ‘adaptive peak hypothesis’

Vegetation phenology and nest survival: Diagnosing heterogeneous effects through time

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