Recapture Heterogeneity in Cliff Swallows: Increased Exposure to Mist Nets Leads to Net Avoidance

Ecologists often use mark-recapture to estimate demographic variables such as abundance, growth rate, or survival for samples of wild animal populations. A common assumption underlying mark-recapture is that all animals have an equal probability of detection, and failure to meet or correct for this assumption–as when certain members of the population are either easier or more difficult to capture than other animals–can lead to biased and inaccurate demographic estimates. We built within-year and among-years Cormack-Jolly-Seber recaptures-only models to identify causes of capture heterogeneity for a population of colonially nesting cliff swallows (Petrochelidon pyrrhonota) caught using mist-netting as a part of a 20- year mark-recapture study in southwestern Nebraska, U.S.A. Daily detection of cliff swallows caught in stationary mist nets at their colony sites declined as the birds got older and as the frequency of netting at a site within a season increased. Experienced birds’ avoidance of the net could be countered by sudden disturbances that startled them into a net, such as when we dropped a net over the side of a bridge or flushed nesting cliff swallows into a stationary net positioned at a colony entrance. Our results support the widely held, but seldom tested, belief that birds learn to avoid stationary mist nets over time, but also show that modifications of traditional field methods can reduce this source of recapture heterogeneity

Recapture heterogeneity in cliff swallows: increased exposure to mist nets leads to net avoidance.

Ecologists often use mark-recapture to estimate demographic variables such as abundance, growth rate, or survival for samples of wild animal populations. A common assumption underlying mark-recapture is that all animals have an equal probability of detection, and failure to meet or correct for this assumption-as when certain members of the population are either easier or more difficult to capture than other animals-can lead to biased and inaccurate demographic estimates. We built within-year and among-years Cormack-Jolly-Seber recaptures-only models to identify causes of capture heterogeneity for a population of colonially nesting cliff swallows (Petrochelidon pyrrhonota) caught using mist-netting as a part of a 20-year mark-recapture study in southwestern Nebraska, U.S.A. Daily detection of cliff swallows caught in stationary mist nets at their colony sites declined as the birds got older and as the frequency of netting at a site within a season increased. Experienced birds' avoidance of the net could be countered by sudden disturbances that startled them into a net, such as when we dropped a net over the side of a bridge or flushed nesting cliff swallows into a stationary net positioned at a colony entrance. Our results support the widely held, but seldom tested, belief that birds learn to avoid stationary mist nets over time, but also show that modifications of traditional field methods can reduce this source of recapture heterogeneity

Endangered Nectar-Feeding Bat Detected by Environmental DNA on Flowers

Leptonycteris nivalis (the Mexican long-nosed bat) is an endangered nectar-feeding bat species that follows “nectar corridors” as it migrates from Mexico to the southwestern United States. Locating these nectar corridors is key to their conservation and may be possible using environmental DNA (eDNA) from these bats. Hence, we developed and tested DNA metabarcoding and qPCR eDNA assays to determine whether L. nivalis could be detected by sampling the agave flowers on which it feeds. We sampled plants with known bat visitations in the Sierra Madre Oriental in Laguna de Sanchez (LS), Nuevo León, Mexico, and in the Chisos Mountains in Big Bend National Park, TX, USA (CB). A total of 13 samples included both swabs of agave umbels and cuttings of individual flowers. DNA metabarcoding was performed as a PCR multiplex that targeted bats (SFF-COI), arthropods (ANML-COI), and plants (ITS2 and rbcL). We targeted arthropods and plants in parallel with bats because future metabarcoding studies may wish to examine all the pollinators and plants within the nectar corridor. We developed and tested the sensitivity and specificity of two qPCR assays. We found that both DNA metabarcoding and qPCR were highly successful at detecting L. nivalis (11 of 13 for DNA metabarcoding and 12 of 13 for qPCR). Swabs and flower cuttings and both qPCR assays detected the species over four replicates. We suggest that L. nivalis leaves substantial DNA behind as it forages for nectar. We also suggest that future studies examine the time since sampling to determine its effect on detection success. The DNA metabarcoding multiplex will be useful for parallel questions regarding pollination ecology, while, with further testing, the qPCR assays will be effective for large-scale sampling for the detection of migration corridors and foraging areas. This work may be relevant to other nectar-feeding bat species, which can likely be detected with similar methodologies

Set of models used in a Cormack-Jolly-Seber recaptures-only analyses of cliff swallows to test hypotheses and estimate apparent survival and detection probability among years.^*^.

*<p>Parameters with interactions are joined by '*', whereas parameters having parallel (additive) relationships are joined by '+'; Akaike's Information Criterion (AIC) values were corrected for over-dispersion (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0058092#pone-0058092-t003" target="_blank">Table 3</a>), yielding quasi-AIC (QAIC_c) values; ΔQAIC_c values and model weights (w_i) were used to rank models; see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0058092#pone-0058092-t001" target="_blank">Table 1</a> for model notations. Here “k” indicates the number of parameters in the model and “QDev” indicates the quasi-deviance of the model.</p>†<p>QAIC_c = 39946.48 for top-ranked model.</p

Definitions for covariate notations used in all Cormack-Jolly-Seber mark-recapture models for a study of recapture heterogeneity in cliff swallows.

<p>Definitions for covariate notations used in all Cormack-Jolly-Seber mark-recapture models for a study of recapture heterogeneity in cliff swallows.</p

Set of models used in a Cormack-Jolly-Seber recaptures-only analyses of cliff swallows to test hypotheses and estimate apparent survival and detection probability for the analysis of flushing.^*^.

*<p>Parameters with interactions are joined by '*', whereas parameters having parallel (additive) relationships are joined by '+'; Akaike's Information Criterion (AIC) values were corrected for over-dispersion (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0058092#pone-0058092-t003" target="_blank">Table 3</a>), yielding quasi-AIC (QAIC_c) values; ΔQAIC_c values and model weights (w_i) were used to rank models; see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0058092#pone-0058092-t001" target="_blank">Table 1</a> for model notations. Here “k” indicates the number of parameters in the model and “QDev” indicates the quasi-deviance of the model.</p>†<p>QAIC_c = 17369.01 for top-ranked model.</p

Proportion of cliff swallows that were caught only on a day on which flushing was done in a given year (Flush) in relation to the total number of swallows by year (N) captured for each age.

<p>Age represents the number of years a bird was an adult following banding.</p

Sample sizes and Cormack-Jolly-Seber recapture-only model specifications for eight analyses of cliff swallows in a mark-recapture study in southwestern Nebraska, U.S.A., 1991–2010.

<p>Net type indicates the style of netting used to capture cliff swallows at a given colony; Years is the number of groups in the analysis except for in the among-years analysis (which had three groups); Occasions is the number of unique dates on which captures occurred across all years except for the among-years analysis in which each year was considered an occasion; Individuals is the number of different swallows included in the analysis (i.e. sometimes the same swallow was captured in multiple years); Effective sample size is the total times swallows were captured across all occasions and groups; ĉ is the measure of overdispersion associated with the analysis and used to calculate QAIC_c values.</p

Identification of Obesity and Cardiovascular Risk in Ethnically and Racially Diverse Populations: A Scientific Statement From the American Heart Association

The purpose of this scientific statement is to describe the limitations of current simple measures, such as the use of BMI with standard thresholds to identify overweight and obesity, as applied to racial and ethnic minorities. The statement also addresses potential alternatives, as well as the diagnosis of obesity based on multiple risk factors, including race and ethnicity. On the basis of our extensive, systematic review of current literature and in collaboration with the American Heart Association’s (AHA) Obesity Committee of the Council on Lifestyle and Cardiometabolic Health, we have also made some key recommendations for clinical practice, research, and public health for improved identification of obesity and cardiovascular risks in a racially and ethnically diverse population

The Cenozoic palaeoenvironment of the Arctic Ocean

The history of the Arctic Ocean during the Cenozoic era (0–65 million years ago) is largely unknown from direct evidence. Here we present a Cenozoic palaeoceanographic record constructed from &gt;400 m of sediment core from a recent drilling expedition to the Lomonosov ridge in the Arctic Ocean. Our record shows a palaeoenvironmental transition from a warm ‘greenhouse’ world, during the late Palaeocene and early Eocene epochs, to a colder ‘icehouse’ world influenced by sea ice and icebergs from the middle Eocene epoch to the present. For the most recent ~14 Myr, we find sedimentation rates of 1–2 cm per thousand years, in stark contrast to the substantially lower rates proposed in earlier studies; this record of the Neogene reveals cooling of the Arctic that was synchronous with the expansion of Greenland ice (~3.2 Myr ago) and East Antarctic ice (~14 Myr ago). We find evidence for the first occurrence of ice-rafted debris in the middle Eocene epoch (~45 Myr ago), some 35 Myr earlier than previously thought; fresh surface waters were present at ~49 Myr ago, before the onset of ice-rafted debris. And the temperatures of surface waters during the Palaeocene/Eocene thermal maximum (~55 Myr ago) appear to have been substantially warmer than previously estimated. The revised timing of the earliest Arctic cooling events coincides with those from Antarctica, supporting arguments for bipolar symmetry in climate change