Winter Breeding Season Research Articles

Identification of quantitative trait loci and associated candidate genes for pregnancy success in Angus–Brahman crossbred heifers

BackgroundIn beef cattle, more than 50% of the energy input to produce a unit of beef is consumed by the female that produced the calf. Development of genomic tools to identify females with high genetic merit for reproductive function could increase the profitability and sustainability of beef production.ResultsGenome-wide association studies (GWAS) were performed using a single-step genomic best linear unbiased prediction approach on pregnancy outcome traits from a population of Angus–Brahman crossbred heifers. Furthermore, a validation GWAS was performed using data from another farm. Heifers were genotyped with the Bovine GGP F250 array that contains 221,077 SNPs. In the discovery population, heifers were bred in winter breeding seasons involving a single round of timed artificial insemination (AI) followed by natural mating for 3 months. Two phenotypes were analyzed: pregnancy outcome to first-service AI (PAI; n = 1,481) and pregnancy status at the end of the breeding season (PEBS; n = 1,725). The heritability was estimated as 0.149 and 0.122 for PAI and PEBS, respectively. In the PAI model, one quantitative trait locus (QTL), located between 52.3 and 52.5 Mb on BTA7, explained about 3% of the genetic variation, in a region containing a cluster of γ-protocadherin genes and SLC25A2. Other QTLs explaining between 0.5% and 1% of the genetic variation were found on BTA12 and 25. In the PEBS model, a large QTL on BTA7 was synonymous with the QTL for PAI, with minor QTLs located on BTA5, 9, 10, 11, 19, and 20. The validation population for pregnancy status at the end of the breeding season were Angus–Brahman crossbred heifers bred by natural mating. In concordance with the discovery population, the large QTL on BTA7 and QTLs on BTA10 and 12 were identified.ConclusionsIn summary, QTLs and candidate SNPs identified were associated with pregnancy outcomes in beef heifers, including a large QTL associated with a group of protocadherin genes. Confirmation of these associations with larger populations could lead to the development of genomic predictions of reproductive function in beef cattle. Moreover, additional research is warranted to study the function of candidate genes associated with QTLs.

Dose-Dependent Testicular Injury and Recovery after Total-Body Irradiation in Rhesus Monkeys.

Testicular injury is a well-documented acute effect of radiation exposure, though little is known about recovery years after irradiation, especially at higher doses. We examined the testes from 143 irradiated and control male rhesus monkeys, who were part of the Radiation Late Effects Cohort over a four-year period. Irradiated animals were exposed to doses ranging from 3.5 to 8.5 Gy of total-body irradiation. The testes were assessed using computed tomography (CT) volumetry, serum testosterone, and histology for deceased members of the cohort. Irradiated animals exhibited dose-dependent testicular atrophy as well as decreased serum testosterone during the winter breeding season when compared to age-matched unirradiated controls. No significant difference in summer testosterone levels was observed. Volumetric and histologic evidence of testicular recovery was present approximately three years postirradiation for animals who received ≤8 Gy. The study demonstrates dose-dependent testicular injury after total-body irradiation and provides evidence for volumetric and spermatogonial recovery even at lethal doses of total-body irradiation in rhesus monkeys.

Residency, home range and inter-annual fidelity of three coastal fish species in a Mediterranean coastal lagoon

In the Gulf of Lion (NW Mediterranean), fish species such as gilthead sea bream Sparus aurata, European seabass Dicentrarchus labrax, and salema Sarpa salpa show seasonal occupation of coastal lagoons, presumably as feeding grounds during their adult life stage. The role of the lagoons in these species' life cycles remains unknown, particularly with respect to their residency, space-use, and inter-annual fidelity. Using acoustic telemetry, the movements of 72 seabream, 58 seabass, and 81 salema were monitored over four years within Prévost Lagoon (Hérault Department, Occitania Region), to characterize (1) the main seasonal patterns of space use inside the lagoon and (2) their annual migrations between the lagoon and the sea. Overall, all three species were highly resident in the lagoon during the spring/summer foraging season; seabass was the only species that also displayed high residency to the lagoon throughout the winter breeding season. The three species showed differences in their space use, although they all mainly inhabited the deep lagoon centre and adjacent shellfish farms, with very small individual home ranges (mean ± SD, 0.12 ± 0.06 km2 over all species). All species showed some inter-annual fidelity to the lagoon (>43% at minimum for seabream) although these fidelity rates were probably underestimated due to fishing mortality, which is probably high during the winter breeding season. Overall, this study reveals that coastal lagoons are key foraging habitats for these species in the Gulf of Lion. The high residency and inter-annual fidelity suggest that any increase of anthropogenic pressure within the lagoon could negatively impact these fish populations. Therefore, protection of such productive habitats could be beneficial for long-term management of emblematic coastal species and the fisheries that they support.

CANINE DISTEMPER VIRUS ECOLOGY: INSIGHTS FROM A LONGITUDINAL SEROLOGIC STUDY IN WILD RACCOONS (PROCYON LOTOR).

Increasing reports of canine distemper virus (CDV) in a variety of hosts, and changing CDV dynamics, have led to renewed interest in the ecology of CDV infections in wildlife. Longitudinal serologic studies provide insights into intrapopulation and intraindividual pathogen dynamics, but few studies in wildlife have been conducted. We used data from 235 raccoons (Procyon lotor) captured on more than one occasion between May 2011 and November 2013 to investigate CDV dynamics in Ontario, Canada. Using mixed multivariable logistic regression, we found that juvenile raccoons were more likely to be seronegative from August to November than from May to July. Using paired titers from CDV-exposed individual raccoons, we determined that the winter breeding season, when there is high intraspecific contact and an increase in susceptible juveniles, may be a period of high risk for CDV exposure. Interestingly, CDV seropositive adult raccoons had nondetectable titers ranging from 1 mo to 1 yr later. Based on our preliminary investigation using two different statistical approaches, CDV exposure was associated with a decrease in parvovirus titer. This result raises important questions about whether virus-induced immune amnesia occurs after CDV exposure, which has been described for measles virus, a closely related pathogen. Overall, our results provide significant insights into CDV dynamics. Further research is needed to investigate whether CDV-induced immune amnesia occurs in raccoons and to determine the potential impacts of a reduced population immunity that may occur secondary to CDV exposure, particularly as it relates to rabies control efforts.

Upwellings, canyons and whales: An important winter habitat for balaenopterid whales off Mauritania, northwest Africa

The aim of this study was to identify critical habitats for baleen whales in the Mauritanian upwelling zone using data collected from a platform of opportunity: a 60 day geophysical survey approximately 100km southwest of Cap Blanc, Mauritania in winter (2012/13). The bathymetry of the 5,500km2 study area was complex, including parts of the Cap Timiris Canyon system. Large whales, including sei and blue whales, accounted for 70% of the 238 cetacean sightings. Species identification was often problematic, especially in the case of balaenopterid whales, so data for all whales of this genus were pooled for the estimation of abundance and distribution. Spatial modelling was applied to estimate abundance and to plot a predicted density map of balaenopterid whales. Depth and the chlorophyll-a concentration when at its peak (in the previous September) were significant predictors of whale density. Point abundance in the study area was estimated at 272 whales (95% CI 265–279) and density was highest in the depth range 500–2,250m near to the canyon system (6.18 whales/100km2 , 95% CI 6.03–6.51). Steep seabed topography created by canyons running off the shelf edge, together with the strong upwelling system, probably create optimal habitats for the euphausiid prey of sei and blue whales. Sei whales were observed skim-feeding at dawn or dusk on seven occasions; in one sighting an aggregation of 18 skim-feeding sei whales were observed. The high density of these baleen whale species in such a highly productive area and direct observation of feeding behaviour in sei whales, provides evidence of feeding during the winter breeding season, when they have previously been presumed to feed less. This study demonstrates the potential value of collecting further data on seismic survey vessels and would improve understanding of cetacean ecology in remote and under-explored regions.

A test for plasticity in sperm motility activation in response to osmotic environment in an anuran amphibian.

Evolutionary theory predicts that selection will favor phenotypic plasticity in sperm traits that maximize fertilization success in dynamic fertilization environments. In species with external fertilization, osmolality of the fertilization medium is known to play a critical role in activating sperm motility, but evidence for osmotic‐induced sperm plasticity is limited to euryhaline fish and marine invertebrates. Whether this capacity extends to freshwater taxa remains unknown. Here, we provide the first test for plasticity in sperm‐motility activation in response to osmotic environment in an anuran amphibian. Male common eastern froglets (Crinia signifera) were acclimated to either low (0 mOsmol kg−1) or high (50 mOsmol kg−1) environmental osmolality, and using a split‐sample experimental design, sperm were activated across a range of osmolality treatments (0, 25, 50, 75, 100, and 200 ± 2 mOsmol kg−1). Unexpectedly, there was no detectable shift in the optimal osmolality for sperm‐motility activation after approximately 13 weeks of acclimation (a period reflecting the duration of the winter breeding season). However, in both the low and high acclimation treatments, the optimal osmolality for sperm‐motility activation mirrored the osmolality at the natural breeding site, indicating a phenotypic match to the local environment. Previously it has been shown that C. signifera display among‐population covariation between environmental osmolality and sperm performance. Coupled with this finding, the results of the present study suggest that inter‐population differences reflect genetic divergence and local adaptation. We discuss the need for experimental tests of osmotic‐induced sperm plasticity in more freshwater taxa to better understand the environmental and evolutionary contexts favoring adaptive plasticity in sperm‐motility activation.

Comparing the social signaling behavior of humpback whales in three group types on the Hawaiian breeding grounds using acoustic tags

Humpback whales (Megaptera novaeangliae) are exceptionally vocal among baleen whale species. While extensive research has been conducted on humpback whale songs, gaps remain in our understanding of other forms of communication, particularly non-song calls. Here, we compare the spectral features and temporal parameters of non-song calls recorded from AcousondeTM tagged humpback whales in three commonly observed group types in the breeding grounds: adult dyads (N = 3), singly escorted mother-calf pairs (N = 4), and competitive groups (N = 4). Recordings were collected off Maui, Hawai’i during the winter breeding seasons of 2019–2021. Individual calls were identified based on visual and aural inspection of spectrograms using Raven Pro 1.6 software, with a total of 842 calls isolated from 47.6 h of acoustic recordings. Competitive groups produced the most calls (N = 358); however, after adjusting for the differences in recording hours and the number of individuals, the call rate (calls/hour/whale) was not significantly different between group compositions. The temporal parameters and frequency measures of calls did not vary significantly across the groups. However, interesting patterns of calling behavior were observed (e.g., competitive groups had the shortest inter-call intervals and the highest frequency calls, and escorted mother-calf pairs had the longest inter-call intervals) and it is possible the lack of statistical significance could be attributed to the small sample size of tag deployments. This study provides new insights into humpback whale vocal communication behavior in the Hawaiian Islands breeding grounds.

Effect of Season on Analysis of Growth in a Population of the Western Lesser Siren, Siren intermedia nettingi, in Northwestern Louisiana

We analyzed growth in a population of Siren intermedia nettingi, Western Lesser Siren, from northwestern Louisiana using a mark–recapture technique employing PIT tags from January 1992 through March 1998. Traps were monitored for eight consecutive trap nights for all four seasons from 1992 to 1996, January and December winter trapping sessions in 1997, and late February through early March in 1998. A total of 1,004 siren captures included 575 original captures and 429 recaptures. A total of 223 sirens were recaptured at least once for a recapture rate of 38.7%. Thirty-five of the original sirens captured were recaptured in the same season and year and were not used in the analyses. Therefore, we had a usable recapture rate of 32.7%. Based on captures, bites by conspecifics, and presence of juveniles in the study pond, we concluded that sirens in this population were most active in autumn and winter and presumably had a winter breeding season. Males grew faster and reached larger sizes than females due to the large energy investment of females that produced ova and the importance of male agonistic behavior toward other male and female conspecifics. The greatest growth occurred in the spring, despite increased activity in autumn and winter. Sirens were least active in the summer. Growth was inversely proportional to size and smaller sirens grew at a faster rate than larger ones.

Effect of seasonal changes on the innate immunity of wild Pseudois nayaur: potential reason for its endangerment.

Seasonal climate change may impose stress on mammal's immune system, but this has never been connected to wildlife endangerment reasons. This study focuses on Pseudois nayaur, a rare Chinese sheep facing a severe situation of disappearing. Wild Pseudois nayaurs in Sichuan, China were observed in this research by an integrated method including habitat environment, foraging rules, and breeding activities investigation in ecology filed, accompanied with immunity research by peripheral blood, including erythrocyte, neutrophils, natural killer cells, and macrophages immunity by means of erythrocyte rosette, phagocytosis, lactate dehydrogenase release and acid alpha-naphthyl acetate esterase method, respectively. The results show that Pseudois nayaurs's innate and red blood cell immunity in autumn and winter Pseudois nayaurs and it may be the results of energy reallocation between reproduction and the immune system. In addition, the environment pressure found in Zhu Balong, Sichuan, China including food reduction, human disturbance, low temperature, and severe drought still existed, which may prevent the Pseudois nayaur from normal immunity enhancement before winter. In conclusion, the innate immunosuppression found in this study especially at their breeding season in autumn and winter may be the ignored cause of wild Pseudois nayaur's endangerment and should be considered in their protection strategy.

Time heals: Boosted breeding seabird populations on restored Cousine Island, Seychelles

AbstractHistorically, Cousine Island was used for agriculture and harvesting various seabird eggs, but following restoration efforts initiated in the 1990s, it has become an important nesting area for Seychelles seabirds. White‐tailed tropicbird (Phaethon lepturus), white tern (Gygis alba), and lesser (Anous tenuirostris) and brown noddy (Anous stolidus) populations were monitored on Cousine Island between 1997 and 2017 to determine the long‐term population responses to various environmental variables during the winter breeding season. White tern, brown noddy, and white‐tailed tropicbird populations are increasing, indicating that island conditions for breeding have improved for these species in the last 20 years. Lesser noddy populations are in decline, but not significantly, with winter air temperature significantly adding to this trend. Lesser noddies are true colonial nesters and are therefore potentially more affected by climatic conditions that result in nest failures and nearshore prey shortages. The relationship between numbers of seasonally breeding species (lesser and brown noddies) and those of year‐round breeders (white‐tailed tropicbirds and white terns) was also examined. Brown noddy population trends significantly predicted white‐tailed tropicbird and white tern winter breeding population trends, suggesting that these species populations respond similarly to local conditions. Data from this study establish a baseline for future population trend investigations and assessments of island conservation and management success.

The social signaling behavior of humpback whales on the Hawaiian breeding grounds investigated using acoustic tags

Humpback whales (Megaptera novaeangliae) are one of the most social of all baleen whale species. Despite extensive research into humpback whale song, gaps remain in the understanding of humpback whale communication. These gaps are particularly evident with respect to humpback whale non-song social vocalizations. This study expands upon the current understanding of non-song social call use and function by comparing call prevalence, features, and dynamics across humpback whale groups of three different compositions: dyads, escorted mother-calf pairs, and competition groups. Recordings were collected from 12 deployments of AcousondeTM acoustic and data logging tags on whales off Maui, Hawaii during the winter breeding seasons of 2019-2021. Individual social calls were selected based on visual and aural inspection of spectrograms using Raven Pro 1.6 software, with a total of 518 calls chosen throughout the 60.4 h of acoustic recordings. Of these calls, 49.2% occurred in competition groups, 33.6% in escorted mother-calf pairs, and 17.2% in dyads. Furthermore, we conducted statistical analyses to characterize and classify the social calls recorded and assess the variability of the type, quantity, and frequency of social calls used in groups of differing compositions. This study provides new insights into humpback whale vocal communication behavior in the Hawaiian Islands breeding grounds, particularly with respect to three principal social groups, whose non-song vocal communications have been understudied.

Where, when, and why do western North Atlantic humpback whales begin to sing?

ABSTRACT At the onset of the winter breeding season, male humpback whales begin a prominent breeding behaviour, singing. Early songs are produced on summer feeding grounds prior to migration, but little is known about the proximate cues for the initiation of this behaviour, nor where or when it begins. We document the phenology of humpback whale singing along the western North Atlantic coast ranging from Newfoundland and Labrador, Canada to Massachusetts, USA through the fall-winter of 2015–16 (seven stations) and 2016–17 (three stations). Acoustic data from static recorders were categorised as containing humpback whale non-song calls, song fragments, or full songs. First heard in September, singing occurred throughout the fall-winter, but was not regular until October. Latitude, temperature, photoperiod, sea surface pressure, and wind speed were considered as potential explanatory variables for four definitions of song onset using forward stepwise regression. Final models included the environmental variables with photoperiod negatively correlated to singing (coefficient = −657; p-value = 0.04). Reliable environmental cues, such as photoperiod, may produce a heritable physiological response, resulting in whales acquiring the capacity and motivation to sing, with the subsequent timing and nature of song production influenced by other factors.

Tracking multiple humpback whales simultaneously using time-frequency representations of active intensity on DIFAR acoustic vector sensors

Humpback whale song consists of sequences of frequency-modulated sounds whose exact purpose remains unknown. Tracking multiple individuals simultaneously may provide insights into song function and assist in population estimation; unfortunately, during the winter breeding season off Hawaii so many whales produce overlapping songs that identifying the same individual becomes challenging on underwater sensors spaced a few kilometers apart. Here we present a triangulation technique using three bottom-mounted DIFAR acoustic vector sensors for tracking multiple animals simultaneously. A time-frequency representation of the dominant azimuth (“azigram”) of the acoustic energy is computed from estimates of the active intensity, (i.e., the conjugate product of pressure and particle velocity). By defining a set of azimuthal sectors, azigrams from each sensor can be subdivided into a series of binary images, with each image associated with energy propagating from a particular azimuthal sector. Spectrogram correlation methods applied to binary images from different sensors yield individual song fragments that can be used to mask the original azigram, yielding the azimuth of the fragment from each sensor, and thus the singer’s position. The technique, which has also been demonstrated on coral reef fish, is illustrated using singer data collected in 2020 off Maui, Hawaii.

Winter breeding season of Brown-throated Martins Riparia paludicola in Morocco

Uniquely among birds of coastal North Africa, Brown-throated Martins breed during the northern winter. Over ten years, the amount of rainfall in the six months before the breeding season was positively correlated with numbers of nests in November, and negatively with nest numbers in January. The evidence available suggests that winter breeding is most likely a response to the availability of insect food, acting through rain-induced vegetation growth, rather than a strategy to avoid predation, competition, or adverse weather conditions. This species may be more able than other species to breed in winter, because their deep nest tunnels provide protection against severe weather.

Estrous detection with an activity and rumination monitoring system in an organic grazing and a low-input conventional dairy herd

The objective of this study was to evaluate estrous detection using a physical activity and rumination monitoring system in a seasonal calving organic grazing (GRAZ) and a low-input conventional (ZEROGRAZ) dairy herd. The study was conducted from June 2014 to August 2017. During each breeding season, physical activity and rumination were monitored electronically using an activity and rumination monitoring system (HR-LD tags; SCR Engineers Ltd., Netanya, Israel). Signals resulting from the activity and rumination monitoring system for individual cows were used to determine consistency of the values using this system with the breeding date of cows. Breeding dates were determined using EstrotectTM patches. The study included 1,463 breeding dates from 531 cows. Within the GRAZ herd, during the summer breeding season the monitoring system was less sensitive for estrous detection (33.8 %) than during the winter breeding season (79.8 %).The activity and rumination monitoring system had a sensitivity of 56.7 %, specificity of 99.3 % and positive predictive value of 59.8 % for the GRAZ herd, and sensitivity of 70.1 %, specificity of 99.2 % and positive predictive value of 66.3 % for the ZEROGRAZ herd. For cows that were determined to be pregnant and subsequently calved as a result of the mating, the sensitivity for estrous detection was slightly greater for the GRAZ (60.7 %) and ZEROGRAZ (72.5 %) herds. The activity and rumination monitoring system evaluated in this study has potential for estrous detection in grazing herds during the winter breeding season and in small-input dairy herds during both, winter and summer breeding seasons.

Population dynamics and regulation of the Middle Spotted Woodpecker in strictly protected and managed forests in Western Poland

Analysis of ecological time series allows to assess the relative contribution of density-dependent and density-independent factors influencing the regulation of the population of a species. In this study, we investigated whether the annual fluctuation in the population of Middle Spotted Woodpeckers Dendrocoptes medius can be attributed to the direct or delayed density-dependent regulation or to the density-independent factors such as weather conditions during the preceding winter and previous breeding season and/or disturbance in the habitat associated with sanitary felling and salvage logging of trees. This study was conducted in the Czeszewo Forest Reserve, which protects the remnants of semi-natural flood-plain forest, and in the Łówkowiec Forest, which is a managed oak-dominated stand, during 19 seasons (2001–2019). Time series diagnostic revealed that the growth rate of population of Middle Spotted Woodpecker in protected semi-natural riverine forest and in managed oak forest was determined by first-order negative feedback, suggesting an important role of direct density-dependent mortality in the regulation of an equilibrium in population size. The effect of density-dependent process varied between study sites, being lower in riverine forest, where population size has increased distinctly in recent years. In both study areas, we detected strong positive effects of wind chill temperature during the preceding winter on population growth rates. We did not find evidence for the assumption that the increase in population growth rate is affected by weather conditions in the previous breeding season and by the disturbance in the habitat associated with sanitary felling and salvage logging of trees. Our results suggest that Middle Spotted Woodpeckers can benefit from global climate warming by an enhanced rate of winter survival or an increase in the accessibility of food, e.g., insects and other arthropods. The lack of time-lag significant correlations between population fluctuations suggests local habitat conditions, e.g., forest management, can modify inter-annual variability in time series of the Middle Spotted Woodpecker.

Two new species of Rhodeus (Teleostei: Cyprinidae: Acheilognathinae) from the River Yangtze, China

Rhodeus cyanorostris sp. nov. and R. nigrodorsalis sp. nov. are described from two tributaries of the River Yangtze, in Sichuan and Jiangxi Provinces, China, respectively. Both species have a small number of branched dorsal-fin rays (both with a mode of 8) and anal-fin rays (mode of 7-8 and 8, respectively), which makes them easily distinguished from all congeners. Rhodeus cyanorostris sp. nov. differs from R. nigrodorsalis sp. nov. in having more predorsal scales (14-16 vs. 12-13), fewer pectoral-fin rays (10-11 vs. 12), a shorter major axis of the eggs (2.5-2.8 mm vs. mostly 3.3-3.5 mm), absence of two rows of light spots on the dorsal-fin rays (vs. presence), and absence of a black blotch on the dorsal fin in adult males (vs. presence). The breeding season in winter of the two new species is unique among the Acheilognathinae.

Detection of Trispot Darter (Percidae: Etheostoma trisella) Using Empirical Sampling and Environmental DNA (eDNA)

Etheostoma trisella (Trispot Darter), previously thought extirpated in Alabama, was recently rediscovered. Although robust sampling was conducted in the areas surrounding the newly discovered population, more sampling is needed to document previously unknown populations. We took empirical sampling and water samples for eDNA analysis at 30 sites throughout the potential range of Trispot Darter in the Coosa River drainage, AL. We conducted sampling during late winter breeding season, when adults migrate to small headwater streams to spawn, at sites chosen from known breeding sites in St. Clair County through tributaries to Weis Reservoir in Cherokee County. Positive detection occurred at 4/30 (1.3%) sites. Trispot Darter was not detected using empirical sampling.

Peri-estrus activity and rumination time and its application to estrus prediction: Evidence from dairy herds under organic grazing and low-input conventional production

The objective of this research was to investigate the peri‑estrus changes in activity and rumination time and their use for estrus prediction using data collected by a collar-mounted accelerometer and rumination system (SCR Engineers Ltd., Netanya, Israel). Two experimental dairy herds (low-input conventional: CONV and organic: ORG) of the University of Minnesota West Central Research and Outreach Center, Morris, MN were monitored during the period from June, 2014 to August, 2017. The herds were seasonally bred, and the study comprised three summer breeding seasons (SUM: June to August) and four winter breeding seasons (WIN: December to February). In the winter, both herds were kept in an outwintering lot or a compost-bedded pack barn. In the summer the CONV herd was housed in a dry-lot, and the ORG herd on pasture. The breeding records of 1462 estrus events (849 CONV and 613 ORG) were used as estrus dates. When the day of estrus (day 0) was compared to the reference-period (day -3, -2, -1, +1, +2, +3, relative to the reference period), increased daily activity was observed for 96% of the estrus events (97% for CONV-SUM, 97% for CONV-WIN, 91% for ORG-SUM, and 95% for ORG-WIN), and a decreased daily rumination was observed for 82% of the estrus events (81% for CONV-SUM, 88% for CONV-WIN, 73% for ORG-SUM, and 86% for ORG-WIN). A logistic regression model was developed based on the deviation from a 7-day moving average, 7-day moving standard deviation, and the daily absolute maximum of 6-h-window cumulative change of the data. A successful threshold of alerting estrus (predicted probability > 0.70) was possible when sensitivity and specificity (%) of the model were 75 and 96 for CONV-SUM, 91 and 99 for CONV-WIN, 51 and 92 for ORG-SUM, and 80 and 99 for ORG-WIN. At a lower threshold (predicted probability > 0.30), the sensitivity and specificity (%) were 89 and 81 for CONV-SUM, 97 and 90 for CONV-WIN, 79 and 75 for ORG-SUM, and 90 and 90 for ORG-WIN. A range of trade-offs between sensitivity and specificity was characterized by receiver operating characteristic curves. Additionally, incorporating rumination time data to activity data alone did not improve the prediction performance substantially. In sum, this technology can help detect peri‑estrus changes and there is potential for optimizing prediction performance through improving prediction algorithms or refining alert thresholds.

Evaluating the use of stable isotope analysis to infer the feeding ecology of a growing US gray seal (Halichoerus grypus) population.

Gray seals (Halichoerus grypus) have been rapidly recolonizing the Northeast US coast, eliciting concern from the fishing industry. However, the ecological effect of this recovery is still unknown and as such, research is needed to better understand how the diet composition of gray seals in US waters will contribute to the ecological impact. While previous research on seal diets has focused on the analysis of hard prey remains, stable isotope analysis presents an alternative method that can be used to describe marine mammal diets when direct observation is impossible. To address this issue, we used stable isotope analysis of gray seal pup vibrissae and lanugo from Monomoy Island, Cape Cod, MA during the 2015/2016 winter breeding season to estimate adult female diet composition during pregnancy. Stable isotope mixing models (SIMM) suggested adult female gray seals were consuming greater amounts of cephalopod prey and less sand lance than previously indicated from analysis of hard prey remains. However, using SIMMs to estimate the diet composition of gray seals remains difficult due to the large number of isotopically similar prey species and uncertainty in tissue-specific, stable isotope trophic enrichment factors. Even so, by combining prey sources into ecologically informative groups and integrating prior information into SIMMs it is possible to obtain additional insights into the diet of this generalist predator.