Mark-recapture Study Research Articles

Dispersal inference from population genetic variation using a convolutional neural network.

The geographic nature of biological dispersal shapes patterns of genetic variation over landscapes, making it possible to infer properties of dispersal from genetic variation data. Here, we present an inference tool that uses geographically distributed genotype data in combination with a convolutional neural network to estimate a critical population parameter: the mean per-generation dispersal distance. Using extensive simulation, we show that our deep learning approach is competitive with or outperforms state-of-the-art methods, particularly at small sample sizes. In addition, we evaluate varying nuisance parameters during training-including population density, demographic history, habitat size, and sampling area-and show that this strategy is effective for estimating dispersal distance when other model parameters are unknown. Whereas competing methods depend on information about local population density or accurate inference of identity-by-descent tracts, our method uses only single-nucleotide-polymorphism data and the spatial scale of sampling as input. Strikingly, and unlike other methods, our method does not use the geographic coordinates of the genotyped individuals. These features make our method, which we call "disperseNN," a potentially valuable new tool for estimating dispersal distance in nonmodel systems with whole genome data or reduced representation data. We apply disperseNN to 12 different species with publicly available data, yielding reasonable estimates for most species. Importantly, our method estimated consistently larger dispersal distances than mark-recapture calculations in the same species, which may be due to the limited geographic sampling area covered by some mark-recapture studies. Thus genetic tools like ours complement direct methods for improving our understanding of dispersal.

Survival and growth assessment after reintroduction of the pocketbook mussel, Lampsilis cardium Rafinesque, 1820 among three streams in Nebraska (USA)

Abstract Freshwater mussels are a globally diverse and fundamental group in aquatic ecosystems. However, 65% of freshwater mussel species have become endangered over the past century and 10% of them are already extinct. Natural population preservation and restoration efforts have been expedited, but the complicated life history of this taxon presents many challenges since species‐specific ecology involved in restoration projects is often poorly understood. Lampsilis cardium is an imperilled freshwater mussel in Nebraska, USA. A reintroduction project has been carried out to restore L. cardium populations among three streams in Nebraska, during autumn 2016 and summer 2017. A 2‐year mark–recapture study was used to determine habitat, timing and size‐at‐introduction effects on mussel survival and growth following introduction. Water quality and habitat parameters were seasonally recorded from each site to assess potential effects on mussel growth and survival. The highest daily growth rates of L. cardium ranged between 145 and 185 μm d−1, whereas the lowest daily growth rates observed were ∼88–107 μm d−1, with the greater rate of shell growth always recorded for those individuals introduced in spring and lower for those individuals introduced in summer or autumn. Survival models indicated that mussels were most susceptible to mortality immediately following introduction in spring, whereas size at introduction had almost no effect on survival. At each site, habitat parameter measurements recorded during different seasons indicated that calcium availability, water temperatures, water depth and water quality may contribute to differences in growth and survival rates. Survival rate estimation and population growth predictions are essential knowledge to understand population dynamics; this study provides useful information and a framework for management decisions that may influence L. cardium population dynamics, such as identifying more suitable habitats and introduction times not only for this species but also other similar unionids.

Natal Philopatry in a Long-Lived Species: The Return of Reproductive River Turtles Marked and Released as Hatchlings

Natal philopatry—the return of an animal to its place of birth to reproduce—can shape population genetics and link essential habitats across generations, yet examples from long-term mark-recapture studies are rare. In this study, we observed 136 nests of Northern Map Turtles at Mount Union, Pennsylvania, between 2000 and 2008 and then individually marked and released 691 hatchling turtles into the Juniata River. During a recent six-year period (from 2017 to 2022), 46 of the hatchling-marked turtles (6.7%) returned to Mount Union as adult females to nest. The ages of these turtles ranged from 11–22 years at first recapture, and their mean age was 17 years. Forty-one hatchling-marked females came from observed nests with known mothers, and remarkably, just four (of 52) mothers produced over half of the returning females. The minimum ages of the oldest female turtles were estimated at 39 years, with reproductive lifetimes of at least 23 years. Our results indicate that a few long-lived Super Moms have made extraordinary contributions to hatchling recruitment and population viability of Northern Map Turtles of the Juniata River. The timing of release also had a significant influence on the probability of a turtle returning, with hatchlings released in May returning at a higher rate than those released earlier in the spring. In addition, morphological characteristics of hatchling-marked females suggest that factors causing shell shape abnormalities in adult turtles have not abated over the past two decades as previously theorized and likely involve exposure of juveniles to contaminants in the Juniata River rather than any maternal influence.

Sex-specific innate immunity and ageing in long-lived fresh water turtles (Kinosternon flavescens: Kinosternidae)

BackgroundThe progressive deregulation of the immune system with age, termed immunosenescence, has been well studied in mammalian systems, but studies of immune function in long-lived, wild, non-mammalian populations are scarce. In this study we leverage a 38-year mark-recapture study to quantify the relationships among age, sex, survival, reproductive output and the innate immune system in a long-lived reptile, yellow mud turtles (Kinosternon flavescens; Testudines; Kinosternidae).MethodsWe estimated rates of survival and age-specific mortality by sex based on mark-recapture data for 1530 adult females and 860 adult males over 38 years of captures. We analyzed bactericidal competence (BC), and two immune responses to foreign red blood cells - natural antibody-mediated haemagglutination (NAbs), and complement-mediated haemolysis ability (Lys) - in 200 adults (102 females; 98 males) that ranged from 7 to 58 years of age captured in May 2018 during their emergence from brumation, and for which reproductive output and long-term mark-recapture data were available.ResultsWe found that females are smaller and live longer than males in this population, but the rate of accelerating mortality across adulthood is the same for both sexes. In contrast, males exhibited higher innate immunity than females for all three immune variables we measured. All immune responses also varied inversely with age, indicating immunosenescence. For females that reproduced in the preceding reproductive season, egg mass (and therefore total clutch mass) increased with age,. In addition to immunosenescence of bactericidal competence, females that produced smaller clutches also had lower bactericidal competence.ConclusionsContrary to the general vertebrate pattern of lower immune responses in males than females (possibly reflecting the suppressive effects of androgens), we found higher levels of all three immune variables in males. In addition, contrary to previous work that found no evidence of immunosenescence in painted turtles or red-eared slider turtles, we found a decrease in bactericidal competence, lysis ability, and natural antibodies with age in yellow mud turtles.

Population dynamics of killer whales (Orcinus orca) in the Crozet Archipelago, southern Indian Ocean: a mark-recapture study from 1977 to 2002

Population size and annual survival probabilities for the killer whales (Orcinus orca) inhabiting the inshore waters of Possession Island, Crozet Archipelago, southern Indian Ocean, were estimated through mark-recapture modelling. Capture histories were generated from a set of photographs taken under a photo-identification protocol and a set of photographs taken opportunistically, between 1964 and 2002. Photographs were selected according to their intrinsic quality and the degree of natural marking of individuals. Under those conditions, only well-marked individuals were considered as ‘marked’ from a capture-recapture perspective. The purpose of this double selection was to minimise identification errors and reduce the heterogeneity of capture probabilities. Abundance estimates were derived from the Mth sequential model for closed populations and adjusted for the proportion of well-marked individuals in the study population and for the number of photo-identified individuals. Under this framework, estimates of 98 (95% CI 70-156) individuals in 1988-89, and 37 (95% CI 32-62) individuals in 1998-2000 are proposed. After a weighted model averaging, the Cormack-Jolly-Seber models with the strongest support from the data produced low survival probability estimates, decreasing from 0.935 (95% CI 0.817-0.979) to 0.895 (95% CI 0.746-0.961) for males, and from 0.942 (95% CI 0.844-0.980) to 0.901 (95% CI 0.742-0.966) for females over the period 1977-2002. A Jolly-Seber model was used as a ‘second opinion’ model. It confirmed the worrying status of the population with a constant survival probability estimated at 0.89 (95% CI 0.84-0.93) and a constant rate of increase (applying to the well-marked fraction of the population) estimated at 0.94 (95% CI 0.90-0.99) for the period 1987-2000. This rate of increase is consistent with the abundance estimates presented here. Possible violations of the underlying model assumptions were investigated and it was concluded that the abundance estimates for the period 1988-89 and the CJS survival estimates should be the most reliable results. It is feared that the killer whales around Possession Island are in sharp decline, as may be true for the whole Crozet Archipelago. The effect of low prey stocks and lethal interactions with fisheries as the most likely causes of this decline are discussed.

Mark-recapture estimates of seasonal abundance and survivorship for bottlenose dolphins (Tursiops truncatus) near Charleston, South Carolina, USA

The stock structure of western North Atlantic bottlenose dolphins (Tursiops truncatus) is complex, with seasonally migratory stocks often overlapping with year-round resident stocks. High rates of exchange between northernmost sites have been documented but movement and seasonal fluctuation in abundance among sites along the southern portion of the US Atlantic coast is not well understood. To better understand seasonal abundance, a three-year mark-recapture study of bottlenose dolphins in coastal and estuarine waters near Charleston, South Carolina, USA was conducted. A robust design was employed in order to minimise bias and more precisely determine seasonal estimates of abundance and concurrently examine temporary immigration/emigration and survivorship. Systematic boat-based surveys were carried out (n = 192) from January 2004 to December 2006. The entire study area was surveyed one week per month; an additional survey was conducted in the months in which seasonal abundance was estimated: January (winter), April (spring), July (summer) and October (autumn). Standard photo-identification techniques were used to accumulate sightings of 521 distinctively marked dolphins, 65% of which were sighted more than once. Pollock’s robust design was applied using MARK and the ensuing abundance estimates were adjusted for the seasonal proportion of unmarked dolphins (ranging from 0.27 to 0.40) in the population. Estimates ranged from 364 (95% CI = 305–442) in January 2004 to 910 (95% CI = 819–1018) in October 2006. Summer abundance estimates were consistently greater than those from winter months, although estimates varied considerably among years. The same model was used to calculate an annual survival rate estimate of 0.951 (95% CI = 0.882–1.00) for marked individuals within the population. A high degree of transience, demonstrated by seasonal influxes of single-sighted individuals, made it difficult to differentiate between mortality and permanent emigration. The results support the occurrence of three distinct dolphin groups found in Charleston waters: year-round residents; seasonal residents; and transients. Reporting abundance and survivorship estimates together is useful in explaining and validating results for populations in which transient individuals occur. These results provide important information for stock and viability assessment of coastal bottlenose dolphins in the western North Atlantic.

Skin Marks in Critically Endangered Taiwanese Humpback Dolphins (Sousa chinensis taiwanensis).

As long-lived apex predators, Indo-Pacific humpback dolphins (Sousa chinensis) are key indicators of marine coastal environmental health. Skin marks can be observed on dorsal body surfaces that are visible during mark-recapture studies that rely on photo-identification (photo-ID) methods. Skin mark prevalence may be an indicator of environmental or anthropogenic stressors in the ecosystem, which may lead to individual and/or population-level health concerns. The prevalence of marks of anthropogenic origin was assessed in the Critically Endangered S. chinensis taiwanensis population along the coasts of central Taiwan. Fifty, twenty-eight, and thirty-four individuals were identified in 2018, 2019, and 2021, respectively. At least one category of injuries was observed in 47 of 57 distinctive individuals (82%), and adults showed a higher prevalence of deep injuries than the other coloration stages. At least one category of skin lesion was observed in 33 of 57 distinctive individuals (58%), and high prevalence of skin lesions was found in mature individuals. Given the difficulty in taking direct observations, skin mark prevalence is proposed as a proxy for estimating habitat health and anthropogenic stressors upon S. chinensis taiwanensis. The moderate-to-high prevalence of skin marks in this study was designated as a warning of risks. This study provides important updated information for the assessment of the health and survival of this population. More effective management measures are urgently needed to reverse the observed population decline.

Structural and Geochemical Assessment of the Coralline Alga Tethysphytum antarcticum from Terra Nova Bay, Ross Sea, Antarctica

Crustose coralline algae (CCA) occur from the tropics to the poles in photic benthic environments. Here, we report on some of the world’s southernmost and coldest CCA sites in Terra Nova, Ross Sea, Antarctica at 74°41′ S. The recently described red alga Tethysphytum antarticum is investigated for its skeletal architecture, its mineralogical and geochemical composition, as well as for its taxonomic classification. A phylogenetic analysis based on molecular genetics and the sequencing of the photosystem II protein D1 (psbA) gave a perfect match with T. antarcticum. Histological sections and micro-CT-scans provide new diagnostic details for the conceptacles (the reproductive organs of the alga). X-ray diffractometry and electron-microprobe measurements yielded a clear high-Mg calcite (~8 mol%) composition of the skeletal parts. Detailed back-scattered electron imaging of polished petrographic thin sections revealed a two-layered thallus (vegetative plant tissue), comprising an organic-rich irregularly calcified basal layer with rectangular cells, overlain by the main thallus. Elemental maps show relatively increased sulphur in the basal layer, clearly tied to organic cell walls. MgCO3 and SrCO3 were targeted with semiquantitative elemental mappings and in an ontogenetic quantitative spot transect. Compared with temperature (−1.95 °C to +1.08 °C), the MgCO3 (mol%) reflects this world’s coldest CCA site temperature with the lowest MgCO3 content of 7.9 ± 1.6 mol%. The along transect variability, however, shows with ~6 mol% a larger MgCO3 variability than expected for the 3 °C intra-annual temperature amplitude in Terra Nova Bay. This implies that in low amplitude settings the biomineralisation control on Mg/Ca ratios can outcompete its temperature sensitivity. Mark-recapture studies, next to the environmental logger station La Zecca are suggested, to perform a detailed growth rate and biomineralisation quantification.

Morphological, Anatomical, and Physiological Signs of Senescence in the Great Fruit-Eating Bat (Artibeus lituratus)

The longevity of bats is longer than expected based on their small body sizes and high metabolic rate. However, signs of senescence have been poorly studied for free-living bats, especially for Neotropical species, because elderly individuals are challenging to find in the wild, and long-term mark-recapture studies are lacking. Here, we present the first record of a free-living Neotropical frugivorous bat, a female Artibeus lituratus (family Phyllostomidae), with impressive signs of senescence. We compare the elderly bat with conspecific juveniles and non-elderly adults morphologically, anatomically, and physiologically. The most noticeable signs of senescence were a significant loss of fur, dark spots on the skin, excessive dental wear, and reduced ability to assimilate sugar. These traits indicate that bats' challenges as they get old can be associated with reduced thermal insulation, ability to chew, and nutrient assimilation. However, by reducing extrinsic causes of mortality, flying capability in old bats with clear signs of senescence may represent a vital survival trait associated with the long lifespan of these animals.

Multistate model to estimate sex‐specific dispersal rates and distances for a wetland‐breeding amphibian population

AbstractHow animals move across space and time in heterogeneous landscapes has important implications for the conservation of imperiled and dispersal‐limited taxa, such as amphibians. Wetland‐breeding amphibians are thought to exhibit strong site fidelity, but there is growing evidence that many species are more vagile than previously assumed. Few studies have quantified breeding dispersal probabilities or distances while also accounting for observational uncertainty, which means that resultant estimates could be biased or confounded with sampling intensity and other demographic rates (e.g., site‐ and time‐specific detection and survival probabilities). Here, we analyze data from a 6‐year capture–mark–recapture study on adult spotted salamanders (Ambystoma maculatum) conducted at 12 wetlands in central Pennsylvania to estimate population dynamics and population structure at multiple scales. We used a multistate, hidden Markov estimator to quantify sex‐specific site fidelity and breeding dispersal as a function of Euclidean distance between wetlands while accounting for imperfect detection. We estimated short‐timescale movements (i.e., those that occur within a single breeding season) and longer timescale movements (i.e., those that occur among breeding seasons) to determine if dispersal rates and distances differed. We found that interannual site fidelity of males varied among wetlands and was positively associated with population density. Females exhibited higher interannual site fidelity and dispersed further than males between breeding seasons. Within breeding seasons, we found that up to 6% of males dispersed to a new wetland each day. Our study is the first to directly compare amphibian breeding dispersal probabilities and distances at multiple scales and provides a robust framework for improving inference on the spatial and temporal patterns of amphibian movement.

Vital dye immersion evaluations with juvenile delta smelt

AbstractImmersion‐based vital dyes were tested as a marking method for use in larval smelt mark–recapture studies. We assessed five fluorescent dyes as a mark for juvenile osmerids: 4‐Di‐1‐ASP, BODIPY FL C12, BODIPY 505/515, Nile red, and calcein. We marked juvenile Delta Smelt, Hypomesus transpacificus, as a proxy for Longfin Smelt, Spirinchus thaleichthys, to determine the efficacy of each as a batch marking technique for osmerids based on dye performance and survival. All groups of Delta Smelt including control groups exhibited high mortality (71%–100%, 5 days after trial), and lowest survival was observed in 4‐Di‐1‐ASP‐treated fish. Highest survival was observed in Nile red‐ and BODIPY FL C12‐treated fish. Fluorescence observations indicated that the brightest, visible fluorescence was seen in calcein and to a lesser extent, 4‐Di‐1‐ASP, followed by BODIPY FL C12 and Nile red. In addition to dye performance, it is recommended that immersion techniques that improve survival be considered.

Mark-recapture of microorganisms.

Fundamental questions in ecology and evolution require the quantitative tracking of individuals across space and time. For more than a century, mark-recapture techniques have been used to estimate demographic events and population dynamics of animal and plant species. Recent developments in molecular barcoding allow for the monitoring of microorganisms while meeting many of the key assumptions of traditional mark-recapture studies. Beyond applications related to the biosecurity of human pathogens, molecular barcoding is emerging as a cost-effective, versatile, and scalable tool to quantify species interactions, biogeographic ranges, and evolutionary dynamics in simple and complex communities. Although there are logistical and ethical issues related to the release of barcoded organisms, mark-recapture provides opportunities to test theory and better understand the evolutionary ecology of microorganisms in the wild.

Longevity, Philopatric Behavior, and Health Condition of the Mona Island Iguana Cyclura stejnegeri

The critically endangered Mona Island iguana, Cyclura stejnegeri, is threatened by nest predation by feral pigs, invasive plants that reduce nesting area, and high juvenile mortality. Even though studies in the last 45 years have been sporadic, they had led to different management actions such as protecting nesting areas from feral pig incursion and expanding suitable nesting sites by eradicating the Australian pine (Casuarina equisetifolia) and other invasive plant species. In addition, from 1999 to 2016 a head-start program (HST) was implemented, to increase the recruitment and survival of juvenile iguanas. In 2021, we conducted a 10-week mark-recapture study to survey the population. Data obtained suggest that the Mona iguana lifespans can exceed 32 years, iguanas are very philopatric staying in the same areas over many years, and that health parameters for HST individuals are similar to those of wild ones. These findings provide new information that should be considered when implementing management actions directed at guaranteeing the survival of the Mona iguana.

Carcass non-recovery rate of franciscana dolphin (Pontoporia blainvillei), calibrated with a drift mark-recapture study at FMA Ia, Brazil

The franciscana dolphin (Pontoporia blainvillei) is one of the smallest dolphins globally and the most threatened in the Southwest Atlantic Ocean. Beach monitoring helps to investigate cetacean strandings within their distributions and assess impacts that cause mortality. Using drifters in mark-recapture studies helps to estimate recovery rates when carcasses are unavailable. The study aims to estimate the non-recovery rate of franciscana carcasses from FMA Ia by comparing the spatial distribution between carcasses and drifters along the coast; correlating the influence of cold fronts with the recovery rate of drifters; estimating the non-recovery rate of carcasses according to the drifters’ results and the meteorological profile in the pre-stranding period; characterizing the death diagnostic with temporal distribution of franciscanas by considering the stranding index and the carcass non-recovery rates. We repeated the release of 54 drifters in two campaigns close to the coast within the range of franciscana dolphins, where beaches are monitored daily, in the north region of Espírito Santo state, Brazil. The carcass stranding hotspots (21%) and drifters (18%) were 10 km apart. Cold fronts significantly increase the number of strandings. Considering the incidence of cold fronts in the pre-stranding period and linear regression from drifters, the median carcass recovery rate is 0.26, 95% IC [0.22 - 0.29], which means that for each stranding, the carcass non-recovery rate varies from 0.78 to 0.71. The range between 265 to 350 estimates the total of carcasses from 77 strandings observed from 2003 to 2021. The record year of strandings was 2014 (n = 14). About 52% of records occurred in summer, and January is the month with the highest occurrence of strandings. Of the conclusive diagnoses (n = 43), around 77% (n = 33) were attributed to incidental capture in gillnets. Estimating the number of carcasses based on stranding records is essential for population viability analyses and conservation purposes, especially considering small and isolated populations as in the present study. To prevent local extinction, a solution to avoid incidental capture, especially along summers, must be addressed quickly.

Individual-level specialisation and interspecific resource partitioning in bees revealed by pollen DNA metabarcoding.

It is increasingly recognised that intraspecific variation in traits, such as morphology, behaviour, or diet is both ubiquitous and ecologically important. While many species of predators and herbivores are known to display high levels of between-individual diet variation, there is a lack of studies on pollinators. It is important to fill in this gap because individual-level specialisation of flower-visiting insects is expected to affect their efficiency as pollinators with consequences for plant reproduction. Accordingly, the aim of our study was to quantify the level of individual-level specialisation and foraging preferences, as well as interspecific resource partitioning, in three co-occurring species of bees of the genus Ceratina (Hymenoptera: Apidae: Xylocopinae), C. chalybea, C. nigrolabiata, and C. cucurbitina. We conducted a field experiment where we provided artificial nesting opportunities for the bees and combined a short-term mark-recapture study with the dissection of the bees’ nests to obtain repeated samples from individual foraging females and complete pollen provisions from their nests. We used DNA metabarcoding based on the ITS2 locus to identify the composition of the pollen samples. We found that the composition of pollen carried on the bodies of female bees and stored in the brood provisions in their nests significantly differed among the three co-occurring species. At the intraspecific level, individual females consistently differed in their level of specialisation and in the composition of pollen carried on their bodies and stored in their nests. We also demonstrate that higher generalisation at the species level stemmed from larger among-individual variation in diets, as observed in other types of consumers, such as predators. Our study thus reveals how specialisation and foraging preferences of bees change from the scale of individual foraging bouts to complete pollen provisions accumulated in their nests over many days. Such a multi-scale view of foraging behaviour is necessary to improve our understanding of the functioning of plant-flower visitor communities.

Migration patterns of Greenland halibut in the North Atlantic revealed by a compiled mark–recapture dataset

Abstract Marine fisheries are often allocated to stocks that reflect pragmatic considerations and may not represent the species’ spatial population structure, increasing the risk of mismanagement and unsustainable harvesting. Here we compile mark–recapture data collected across the North Atlantic to gain insight into the spatial population structure of Greenland halibut (Reinhardtius hippoglossoides), an issue that has been unresolved for decades. The dataset contains 168130 fish tagged from 1952 to 2021, with 5466 (3.3%) recaptured individuals. Our results indicate that fish tagged at <50 cm body length migrate at higher rates, suggesting that mark–recapture studies on adult individuals underestimate population-level migration rates. We find evidence for migrations across management units in the North Atlantic indicating two regional offshore populations: one in the Northeast Atlantic, where the West Nordic and Northeast Arctic stocks, currently managed separately, likely belong to a single population that spans from the Kara Sea to Southeast Greenland; and one in the Northwest Atlantic where migration was observed between the Newfoundland and Labrador stock and the Northwest Arctic stock in Davis Strait and Baffin Bay. Our findings indicate complex population structure with implications for international and domestic fisheries management of this long-lived species.

Neckband loss and its effect on apparent survival estimates in Greylag Geese (Anser anser): variation with season, sex and age

Mark-recapture studies enable us to estimate population parameters such as survival, if marks do not impact survival and if marks are not lost. Mark loss can result from external wear and damage, but also behavioural factors may be important and could explain differences between seasons or sexes. We studied Greylag Geese (Anser anser) in eastern Netherlands, ringed with neckbands, leg bands and metal rings (912 geese), observed weekly during 1997–2019 (131,625 observations). Given the double marking and high annual resighting probabilities (neckbands: 0.974, leg rings: 0.639), we quantified neckband loss and the effect of neckbands on apparent survival, using multistate mark-recapture models. Annual neckband loss was 0.038, was higher in males (0.056) than females (0.021) and increased with years since marking, up to 0.098 for males more than 8 years after marking. Neckband loss tended to be higher during December–May than June–November, with most losses occurring in March–April. Both the higher loss in males and the peak in spring in both sexes could result from intraspecific fighting (pulling each other’s neck and neckband). Survival was underestimated in Cormack-Jolly-Seber models that did not account for neckband loss, by up to 0.096 for adult males 6–7 years after marking. Thus, ignoring neckband loss may give erroneous survival differences between sexes and seasons, and overestimate the effect of ageing on survival (i.e. senescence). We did not detect an effect of neckbands on mortality, but statistical power for this test was limited. Neckband loss, although lower nowadays than in studies of decades ago, still impacts survival estimates and should be considered in mark-recapture studies.

Differences in phenology, daily timing of activity, and associations of temperature utilization with survival in three threatened butterflies

We used observational data collected during a mark-recapture study that generated a total of 7503 captures of 6108 unique individuals representing three endangered butterfly species to quantify inter-and intraindividual variation in temperature utilization and examine how activity patterns vary according to season, time of day, and ambient temperature. The Marsh Fritillary, the Apollo, and the Large Blue differed in utilized temperatures and phenology. Their daily activity patterns responded differently to temperature, in part depending on whether they were active in the beginning, middle or end of the season, in part reflecting interindividual variation and intraindividual flexibility, and in part owing to differences in ecology, morphology, and colouration. Activity temperatures varied over the season, and the Apollo and the Large Blue were primarily active at the highest available ambient temperatures (on the warmest days and during the warmest part of the day). The Marsh Fritillary was active early in the season and decreased activity during the highest temperatures. The relationship between individual lifespan and the average temperature was qualitatively different in the three species pointing to species-specific selection. Lifespan increased with an increasing range of utilized temperatures in all species, possibly reflecting that intra-individual flexibility comes with a general survival benefit.

Genus-specific and Habitat-dependent Plant Ingestion in West African Sabre-toothed Frogs (Anura, Odontobatrachidae: Odontobatrachus)

Although frogs are predominately opportunistic carnivores, numerous studies report large amounts of plant material in anuran stomachs, citing accidental ingestion as the likely cause. Herein, we present evidence suggesting deliberate plant uptake in the Sabre-toothed Frog (Odontobatrachus ziama) and propose that this trait is specific to the entire family Odontobatrachidae. We performed stomach-flushing on 814 frogs, resulting in 665 dietary samples comprising all 5 Odontobatrachus species and two similar-sized, syntopic frogs, Astylosternus occidentalis and Conraua alleni. We collected dietary samples across the entire range of Odontobatrachus, in both wet and dry season. Additionally, we collected stomach contents of an O. ziama population during a 12-d capture–mark–recapture study in three different river habitats and compared the consumed and available plant material. We found that all Odontobatrachus spp. ingested the pinnate leaf of the riparian tree Parkia bicolor. These leaves were the most abundant food items in the stomachs of three out of the five Odontobatrachus species. Although mean proportional uptake of the leaflets did not differ seasonally, the maximum amount of leaflets was greater during the dry season, coinciding with peak leaflet availability. We found up to 100 single leaflets in stomachs of Odontobatrachus arndti, but syntopic Astylosternus and Conraua had ingested considerably smaller quantities of Parkia leaflets. Lastly, we found a greater prevalence of Parkia leaflets in females, with significant variation in leaflet uptake between stream microhabitats that could not be explained by the availability of the plant material. Consequently, we analyzed the dietary items for co-occurrences of plant material and preyed-upon animals that would support the hypothesis of an accidental uptake. However, we could not find biologically meaningful co-occurrences. Based on the combined results of stomach-flushing, availability of food items, absence of meaningful co-occurrences of plant with animal matter and feeding experiment, we concluded that leaflets were likely swallowed deliberately, but not eaten for energy demands. The reason for the deliberate ingestion of plant material across the genus Odontobatrachus so far remains unresolved. Key words: Astylosternus occidentalis; Conraua alleni; Frog diet; Guinea; Herbivory; Parkia bicolor; Stomach-flushing

Demography of botfly (Cuterebra fontinella) parasitism in white-footed mice (Peromyscus leucopus) in Kansas

Abstract Botflies (Diptera: Cuterebra sp.) are widely distributed and seasonally abundant parasites of small mammals in North America. To assess their effect on rodent survival, we studied the demography of botfly parasitism on small mammals in northeastern Kansas during 1995–1999. Additional comparisons on botflies parasitizing small mammals were made to a nearby old-field grid where mark–recapture studies continued from 1975 to 2003. White-footed mice, Peromyscus leucopus, were infected by botfly larvae (Cuterebra fontinella) each year during our study. The period of infection for P. leucopus was June–December, with the highest proportion of mice infected in July and August. A smaller, second peak of infection in October and November indicated that C. fontinella reproduced bimodally at this latitude with distinct summer and autumn population peaks. During the botfly seasons of the 5 years, 140 (23.3%) of 602 P. leucopus captured were infected. The percentages of individuals infected during 1995, 1996, 1997, and 1999 were not significantly different (22.4%, 17.3%, 17.1%, and 22.7%, respectively). However, in 1998, 32.4% individuals were infected with a higher incidence of multiple infections and a greater number of botfly larvae per host. Nearly half (47%) of the infected individuals caught in 1998 had infections in both summer and autumn, compared with 25% during the 1995–1997 seasons. In 1999, 63% of infected mice had at least a 2nd infection during the autumn. For all 5 years, 82%, 14%, and 4% of the infected mice had one, two, or three botflies, respectively. In 1998, 24% of the infected mice carried two or more botflies at one time, compared to 14% from 1995–1997 and 11% in 1999. Overall 94% of the infected mice were adults, with no differences between sexes. The variation seen in the prevalence of botfly parasitism of white-footed mice correlates to yearly weather fluctuations. Other demographic aspects of the infected mice, such as sex ratio, age, and longevity of those infected, did not change year to year. Our data suggest that infection with Cuterebra has little negative or positive impact upon populations of white-footed mice.