Long-Term Monitoring of Scripps's Murrelet and Guadalupe Murrelet at San Clemente Island, California: Evaluation of Baseline Data in 2012–2016

The Baja California Pacific Islands (BCPI) is a seabird hotspot in the southern California Current System supporting 129 seabird breeding populations of 23 species and over one million birds annually. These islands had a history of environmental degradation because of invasive alien species, human disturbance, and contaminants that caused the extirpation of 27 seabird populations. Most of the invasive mammals have been eradicated and colonies have been restored with social attraction techniques. We have recorded the number of breeding pairs annually for most of the colonies since 2008. To assess population trends, we analyzed these data and show results for 19 seabird species on ten island groups. The maximum number of breeding pairs for each nesting season was used to estimate the population growth rate (λ) for each species at every island colony. We performed a moving block bootstrap analysis to assess whether seabird breeding populations are increasing or decreasing. San Benito, Natividad, and San Jerónimo are the top three islands in terms of abundance of breeding pairs. The most widespread species is Cassin’s Auklet (Ptychoramphus aleuticus) with 14 colonies. Thirty-one populations of 14 species are significantly increasing while eleven populations of seven species are decreasing. We did not find statistical significance for 19 populations, however, 15 have λ>1 which suggest they are growing. Twelve of the 18 species for which we estimated a regional population trend are significantly increasing, including seven surface-nesting species: Brandt’s Cormorant (Phalacrocorax penicillatus), Brown Pelican (Pelecanus occidentalis), Caspian Tern (Hydroprogne caspia), Double-crested Cormorant (P. auritus), Elegant Tern (Thalasseus elegans), Laysan Albatross (Phoebastria immutabilis) and Western Gull (Larus occidentalis), and five burrow-nesting species: Ainley’s (Hydrobates cheimomnestes), Ashy (H. homochroa) and Townsend’s (H. socorroensis) Storm-Petrels, and Craveri’s (Synthliboramphus craveri) and Guadalupe (S. hypoleucus) Murrelets. The BCPI support between 400,000 and 1.4 million breeding individuals annually. Our results suggest that these islands support healthy and growing populations of seabirds that have shown to be resilient to extreme environmental conditions such as the “Blob”, and that such resilience has been strengthen from conservation and restoration actions such as the eradication of invasive mammals, social attraction techniques and island biosecurity.

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“…Record by [59] for the 2007-2008 breeding season, during our own surveys we just found and confirmed Scripps's Murrelet.…”

Section: Status Of the Seabird Breeding Populationssupporting

confidence: 73%

Population trends of seabirds in Mexican Islands at the California Current System

Méndez-Sánchez¹,

Guzmán²,

Rojas-Mayoral³

et al. 2022

PLoS ONE

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“…The positive response of murrelets at Anacapa provides justification for further conservation efforts, particularly localized predator control or exclosures to protect isolated murrelet breeding habitats on islands where native and introduced mammalian predators are present (McChesney and Tershy ). Finally, the similar λs estimated from nest monitoring and spotlight survey data confirmed the utility of spotlight surveys as a monitoring tool, especially at islands where large samples of monitored nests may not be possible (e.g., San Clemente Island, California; Whitworth et al, ). With only 13 Scripps's murrelet breeding islands and 2 documented Guadalupe murrelet ( S. hypoleucus ) breeding islands, periodic monitoring is essential to conservation efforts for these vulnerable species.…”

Section: Management Implicationssupporting

confidence: 54%

Population trends for Scripps's murrelet following eradication of black rats

Whitworth

Carter

2017

J Wildl Manag

Self Cite

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Nest monitoring at Anacapa Island, California, USA, in 2001-2010 documented considerable benefits for Scripps's murrelets (Synthliboramphus scrippsi) following the eradication of black rats (Rattus rattus) in 2002. In 2014, post-eradication monitoring resumed at Anacapa to update the number of occupied nests in monitored plots, count murrelets in nocturnal at-sea congregations near Anacapa using round-island spotlight surveys, and compare post-eradication rates of population change (l) estimated from nest counts and spotlight surveys. Nest counts and spotlight counts demonstrated increases; the overall number of nests increased 4.45 times from 2001 (11 nests) to 2014 (60 nests) and mean round-island counts in 2014 (869 AE 592 [SD]) were higher than in 2001-2003. Time series regression yielded annual increases that were marginally higher for nests (l ¼ 1.151) compared to round-island counts (l ¼ 1.122). The slight difference may have resulted from inherent differences in the indices used to measure l, spatial biases in nest plots, data gaps in the regressions, and small sample biases for round-island counts. The post-eradication l for murrelets at Anacapa was slightly higher than the mean response reported for other Alcidae (l ¼ 1.113). This was the first use of spotlight surveys to estimate l based on counts of seabirds congregating at-sea near breeding areas. This study provided vital information needed to better assess the risks and benefits of future island restoration actions, justification for further murrelet conservation efforts, and confirmation of spotlight surveys as a population monitoring tool for Scripps's murrelets. Ó 2017 The Wildlife Society.

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“…Several researchers have further evaluated different sampling approaches as a means for reducing sampling bias for deer (e.g., aerial, infrared camera, thermal imaging), although these methods may not be cost‐effective or easily applied to landscape‐scale studies (Naugle et al , Roberts et al , McShea et al , Beaver et al ). Alternatively, fewer studies have evaluated or recommended statistical approaches for improving spotlight data analyses beyond distance sampling (Balaguera‐Reina et al , Whitworth et al ). Boyce () recommended that researchers should not force data into statistical frameworks inappropriate for the data but rather consider the distribution of used observations as a direct sample of the distribution of random landscape locations.…”

mentioning

confidence: 99%

Using spotlight observations to predict resource selection and abundance for white‐tailed deer

2019

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Spotlight surveys for white‐tailed deer (Odocoileus virginianus) can yield large presence‐only datasets applicable to a variety of resource selection modeling procedures. By understanding how populations distribute according to a given resource for a reference area, density and abundance can be predicted across new areas assuming the relationship between habitat quality (measured by an index of selection) and species distribution are equivalent. Habitat‐based density estimators have been applied to wildlife species and are useful for addressing conservation and management concerns. Although achieving reliable population estimates is a primary goal for spotlighting studies, presence‐only models have yet to be applied to spotlight data for estimating habitat selection and abundance for deer. From 2012 to 2017, we conducted spring spotlight surveys in each of 99 counties in Iowa, USA, and collected spatial locations for 20,149 groups of deer (n = 71,323 individuals). We used a resource selection function (RSF) based on deer locations to predict the relative probability of use for deer at the population level and to estimate statewide abundance. The number of deer observed statewide increased significantly with increasing RSF value for all years and the mean RSF value along survey transects explained 59% of the variability in county‐level deer counts, indicating that a functional response between habitat quality and deer distribution existed at landscape scales. We applied our RSF to a habitat‐based density estimator (extrapolation) and zero‐inflated Poisson (ZIP) and negative binomial (ZINB) count models to predict statewide abundance from spotlight counts. Population estimates for 2012 were variable, indicating that atypical weather conditions may affect spotlight counts and population estimates in some years. For 2013–2017, we predicted a mean population of 439,129 (95% CI ∼ ± 55,926), 440,360 (∼ ± 43,676), and 465,959 (∼ ± 51,242) deer across years for extrapolation, ZIP, and ZINB models, respectively. Estimates from all models were not significantly different than estimates from an existing deer population accounting model in Iowa for 2013 and 2016, and differed by <76,000 deer for all models from 2013–2017. Extrapolation and ZIP models performed similarly and differed by <2,897 deer across all years, whereas ZINB models showed inconsistencies in model convergence and precision of estimates. Our results indicate that presence‐only models are capable of producing reliable and precise estimates of resource selection and abundance for deer at broad landscape scales in Iowa and provide a tool for estimating deer abundance in a spatially explicit manner. © 2019 The Wildlife Society.

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Long-Term Monitoring of Scripps's Murrelet and Guadalupe Murrelet at San Clemente Island, California: Evaluation of Baseline Data in 2012–2016

Cited by 7 publications

References 17 publications

Population trends of seabirds in Mexican Islands at the California Current System

Population trends of seabirds in Mexican Islands at the California Current System

Population trends for Scripps's murrelet following eradication of black rats

Using spotlight observations to predict resource selection and abundance for white‐tailed deer

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