GenEst statistical models—A generalized estimator of mortality

Dalthorp, Daniel; Madsen, Lisa; Huso, Manuela M.; Rabie, Paul A.; Wolpert, Robert L.; Studyvin, Jared; Simonis, Juniper L.; Mintz, Jeffrey

doi:10.3133/tm7a2

Cited by 29 publications

(51 citation statements)

References 1 publication

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“…We used fatal collision counts to generate adjusted fatality estimates that account for human and scavenger removal of carcasses between surveys and for observer detection probability of carcasses present during surveys. We generated these bias-adjusted estimates using the GenEst statistical estimator [45], which allows modeling of carcass persistence and detection probabilities as a function of one or more covariates. This estimator also accounts for varying time intervals between surveys when estimating carcass persistence probability, which allowed us to account for: (1) missed surveys due to the above-described access issues for some buildings and days (a survey was considered missed if ≥50% of the building perimeter was not surveyed), and (2) varying time intervals between successive surveys for days when only morning surveys were conducted versus days when morning, midday, and evening surveys were conducted.…”

Section: Methodsmentioning

confidence: 99%

Factors influencing bird-building collisions in the downtown area of a major North American city

et al. 2019

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Bird-building collisions are the largest source of avian collision mortality in North America. Despite a growing literature on bird-building collisions, little research has been conducted in downtown areas of major cities, and no studies have included stadiums, which can be extremely large, often have extensive glass surfaces and lighting, and therefore may cause many bird collisions. Further, few studies have assessed the role of nighttime lighting in increasing collisions, despite the often-cited importance of this factor, or considered collision correlates for different seasons and bird species. We conducted bird collision monitoring over four migration seasons at 21 buildings, including a large multi-use stadium, in downtown Minneapolis, Minnesota, USA. We used a rigorous survey methodology to quantify among-building variation in collisions and assess how building features (e.g., glass area, lighting, vegetation) influence total collision fatalities, fatalities for separate seasons and species, and numbers of species colliding. Four buildings, including the stadium, caused a high proportion of all collisions and drove positive effects of glass area and amount of surrounding vegetation on most collision variables. Excluding these buildings from analyses resulted in slightly different collision predictors, suggesting that factors leading some buildings to cause high numbers of collisions are not the exact same factors causing variation among more typical buildings. We also found variation in collision correlates between spring and fall migration and among bird species, that factors influencing collision fatalities also influence numbers of species colliding, and that the proportion, and potentially area, of glass lighted at night are associated with collisions. Thus, reducing bird collisions at large buildings, including stadiums, should be achievable by reducing glass area (or treating existing glass), reducing light emission at night, and prioritizing mitigation efforts for glass surfaces near vegetated areas and/or avoiding use of vegetation near glass.

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Section: Methodsmentioning

confidence: 99%

Factors influencing bird-building collisions in the downtown area of a major North American city

et al. 2019

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“…Recorded detection and persistence times were frequently either interval-censored, due to camera trap failure to record the exact scavenging time, or right-censored, because some carcasses persisted until the end of the experiments. We fitted accelerated failure time (AFT) models using the parametric distribution (among the ones most commonly used in carcass persistence models, namely, exponential, Weibull, log-logistic and log-normal 53,54 ) that best described carcass detection/persistence times, based on Akaike Information Criterion (see Supplementary material, Table S2, S3, S4 and S5). To assess LI effect on carcass persistence, we fitted separate AFT models for the V. F. Xira and Évora regions, both including 'Treatment' (Control, Power line, Road) as an explanatory variable.…”

Section: Discussionmentioning

confidence: 99%

“…For instance, carcass persistence within PL right-of-way was considerably higher in V. F. Xira (mean time 7.32 ± 0.96 days), compared to Évora (mean time 3.37 ± 0.46 days). According to the recently developed "Generalized Estimator" (GenEst) software 54 , in a scenario of weekly carcass searches, the estimated probability of a small carcass persisting until the day of the search is 0.58 in V. F. Xira, but decreases to 0.43 in Évora. This means that, one would have to multiply the number of bird carcasses found by a factor of 1.7 in V. F. Xira and 2.3 in Évora, to obtain the corresponding bird fatality estimates adjusted for scavenging bias.…”

Section: Effect On Scavenger Identity and Carcass Persistence Sevmentioning

confidence: 99%

Response of vertebrate scavengers to power line and road rights-of-way and its implications for bird fatality estimates

Bernardino

Bispo

Martins

et al. 2020

Sci Rep

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Linear infrastructures, such as power lines and roads, are an important source of bird mortality. However, little is known on the potential effect of these infrastructures on local scavenger guilds, their foraging activity and the resulting bird carcass removal patterns. This is an important source of bias in studies aiming to quantify bird fatalities due to linear infrastructures. We used camera-traps to record scavenger identity and persistence patterns of bird carcasses placed close to linear infrastructure and nearby controls in two Mediterranean agricultural regions. We found that linear infrastructure influence on scavenger identity varied depending on the region. Contrary to expectations, linear infrastructure presence had either none or a positive effect on carcass persistence, meaning that carcasses placed within power line or road rights-of-way were not removed faster than the ones placed in controls. We conclude that linear infrastructure effect on vertebrate scavenging patterns is likely to be region-specific, and that reliable correction factors for carcass removal-bias in bird fatality estimates require site-specific experiments to characterize local scavenging processes.

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“…These numerical assessments use a newly developed suite of field‐based and statistical tools for collecting and interpreting survey data (e.g., Dalthorp et al. ). As a consequence, they often can answer the first key question above, about how many individuals are affected.…”

Section: Introductionmentioning

confidence: 99%

Assessing population‐level consequences of anthropogenic stressors for terrestrial wildlife

et al. 2020

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Human activity influences wildlife. However, the ecological and conservation significances of these influences are difficult to predict and depend on their population-level consequences. This difficulty arises partly because of information gaps, and partly because the data on stressors are usually collected in a count-based manner (e.g., number of dead animals) that is difficult to translate into rate-based estimates important to infer population-level consequences (e.g., changes in mortality or population growth rates). However, ongoing methodological developments can provide information to make this transition. Here, we synthesize tools from multiple fields of study to propose an overarching, spatially explicit framework to assess population-level consequences of anthropogenic stressors on terrestrial wildlife. A key component of this process is using ecological information from affected animals to upscale from count-based field data on individuals to rate-based demographic inference. The five steps to this framework are (1) framing the problem to identify species, populations, and assessment parameters; (2) field-based measurement of the effect of the stressor on individuals; (3) characterizing the location and size of the populations of interest; (4) demographic modeling for those populations; and (5) assessing the significance of stressor-induced changes in demographic rates. The tools required for each of these steps are well developed, and some have been used in conjunction with each other, but the entire group has not previously been unified together as we do in this framework. We detail these steps and then illustrate their application for two species affected by different anthropogenic stressors. In our examples, we use stable hydrogen isotope data to infer a catchment area describing the geographic origins of affected individuals, as the basis to estimate population size for that area. These examples reveal unexpectedly greater potential risks from stressors for the more common and widely distributed species. This work illustrates key strengths of the framework but also important areas for subsequent theoretical and technical development to make it still more broadly applicable.

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GenEst statistical models—A generalized estimator of mortality

Cited by 29 publications

References 1 publication

Factors influencing bird-building collisions in the downtown area of a major North American city

Factors influencing bird-building collisions in the downtown area of a major North American city

Response of vertebrate scavengers to power line and road rights-of-way and its implications for bird fatality estimates

Assessing population‐level consequences of anthropogenic stressors for terrestrial wildlife

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