Search

Long-term movements of adult marine animals predicate spatial management measures. Sea cucumbers are intensely exploited worldwide, yet few studies have assessed their long-term movement potential. Elephant trunkfish, Holothuria (Microthele) fuscopunctata, is a large coral reef holothuroid. At four sites at Lizard Island, northern Great Barrier Reef, we photographically marked and georeferenced 36 H. fuscopunctata, ranging 1.4–5.1 kg in weight. In broader searches one year later, we recaptured 92% of the animals. Their displacements were comparable among sites and averaged 8.7 m yr−1. None of the movements could be characterised as nomadic; the maximum displacement was 21 m. Contrary to expectations, smaller animals tended to roam further than larger animals (p = 0.025). Our study shows that certain large-bodied sea cucumbers might not displace far over annual timescales. This empirical evidence of home ranging reshapes our understanding of echinoderm mobility and reveals a behaviour that would exacerbate Allee effects at low population densities. [ABSTRACT FROM AUTHOR]

Understanding the geographical distribution of phenotypically highly similar species (i.e. cryptic species) represents a challenge to biogeographers, due to the obvious difficulties in identifying such taxa without specific expertise. Besides, citizen science is increasingly emerging as a key approach for supporting biodiversity data collection, but remains hard to apply in the case of cryptic species. Here we aim to test the combination of community records and photography‐based quantitative methods, for assessing the distribution of cryptic taxa, by using two grasshopper species of the genus Aiolopus as models. To achieve these objectives, we first assess the reliability of photography‐based diagnostic criteria to differentiate between A. thalassinus and A. puissanti without ambiguity from correctly identified records, and then apply such criteria to geographical regions of potential range overlap between the two species, in order to clarify their respective distributions. By applying a multivariate classification approach based on ratio measurements taken from photographs, we provide a quantitative tool to successfully identify the two species, and disclose that A. puissanti widely occurs outside of its currently known range, and outline potential research avenues on the biogeography of these poorly studied species. Our results also point at how some types of cryptic species may be effectively identified by adopting a quantitative photography‐based approach, with applicability for clarifying species' distributions at wide scales by exploiting publicly available citizen‐science records. Our study thus, besides shedding light onto the biogeography and distributions of Aiolopus grasshoppers across the Mediterranean, represents an effective and repeatable framework to disentangle the distributions of poorly studied cryptic species. [ABSTRACT FROM AUTHOR]

Reliable estimates of population size and demographic rates are central to assessing the status of threatened species. However, obtaining individual‐based demographic rates requires long‐term data, which is often costly and difficult to collect. Photographic data offer an inexpensive, noninvasive method for individual‐based monitoring of species with unique markings, and could therefore increase available demographic data for many species. However, selecting suitable images and identifying individuals from photographic catalogs is prohibitively time‐consuming. Automated identification software can significantly speed up this process. Nevertheless, automated methods for selecting suitable images are lacking, as are studies comparing the performance of the most prominent identification software packages. In this study, we develop a framework that automatically selects images suitable for individual identification, and compare the performance of three commonly used identification software packages; Hotspotter, I3S‐Pattern, and WildID. As a case study, we consider the African wild dog, Lycaon pictus, a species whose conservation is limited by a lack of cost‐effective large‐scale monitoring. To evaluate intraspecific variation in the performance of software packages, we compare identification accuracy between two populations (in Kenya and Zimbabwe) that have markedly different coat coloration patterns. The process of selecting suitable images was automated using convolutional neural networks that crop individuals from images, filter out unsuitable images, separate left and right flanks, and remove image backgrounds. Hotspotter had the highest image‐matching accuracy for both populations. However, the accuracy was significantly lower for the Kenyan population (62%), compared to the Zimbabwean population (88%). Our automated image preprocessing has immediate application for expanding monitoring based on image matching. However, the difference in accuracy between populations highlights that population‐specific detection rates are likely and may influence certainty in derived statistics. For species such as the African wild dog, where monitoring is both challenging and expensive, automated individual recognition could greatly expand and expedite conservation efforts. [ABSTRACT FROM AUTHOR]

Photographic identification is increasingly being used as a cost-effective and minimally invasive method to monitor species, which is of particular importance for endangered populations that are vulnerable to intrusive research methods. The purpose of our study was to collect photographs of an endangered population of beluga whales (Delphinapterus leucas (Pallas, 1776)) in Cumberland Sound, Nunavut, Canada, for use in photographic identification. Rather than pursuing the whales with boats to collect photographs, drones were used to minimize disturbance. We analyzed drone photographs from 2017 to 2019 for distinctive markings on the whales, which were used to develop a photographic identification catalogue. In total, 93 individuals were identified, with 24 resightings of marked individuals over the survey period. Approximately 43.4% (standard error 3.3%) of the adult beluga population was uniquely marked. The beluga population has been harvested at a rate of 41 whales per year, not including struck and lost, since 2002. The markings were from unknown origins (61%), scars/wounds from gunshots (27%), anthropogenic or predatory given the size and severity (11%), or a satellite tag (1%). The continuation of the photographic identification program will allow for the estimation of important population demographics, such as abundance and calving interval, which are important parameters for population conservation and management.

Abstract Reliable estimates of population size and demographic rates are central to assessing the status of threatened species. However, obtaining individual‐based demographic rates requires long‐term data, which is often costly and difficult to collect. Photographic data offer an inexpensive, noninvasive method for individual‐based monitoring of species with unique markings, and could therefore increase available demographic data for many species. However, selecting suitable images and identifying individuals from photographic catalogs is prohibitively time‐consuming. Automated identification software can significantly speed up this process. Nevertheless, automated methods for selecting suitable images are lacking, as are studies comparing the performance of the most prominent identification software packages. In this study, we develop a framework that automatically selects images suitable for individual identification, and compare the performance of three commonly used identification software packages; Hotspotter, I3S‐Pattern, and WildID. As a case study, we consider the African wild dog, Lycaon pictus, a species whose conservation is limited by a lack of cost‐effective large‐scale monitoring. To evaluate intraspecific variation in the performance of software packages, we compare identification accuracy between two populations (in Kenya and Zimbabwe) that have markedly different coat coloration patterns. The process of selecting suitable images was automated using convolutional neural networks that crop individuals from images, filter out unsuitable images, separate left and right flanks, and remove image backgrounds. Hotspotter had the highest image‐matching accuracy for both populations. However, the accuracy was significantly lower for the Kenyan population (62%), compared to the Zimbabwean population (88%). Our automated image preprocessing has immediate application for expanding monitoring based on image matching. However, the difference in accuracy between populations highlights that population‐specific detection rates are likely and may influence certainty in derived statistics. For species such as the African wild dog, where monitoring is both challenging and expensive, automated individual recognition could greatly expand and expedite conservation efforts.

Abstract Harbour seals (Phoca vitulina) and grey seals (Halichoerus grypus) both occur within the UK, but display regional contrasting population trends. While grey seals are typically increasing in number, harbour seals have shown varying trends in recent decades following repeated pandemics. There is a need for monitoring of regional and local populations to understand overall trends. This study utilized a 20‐year dataset of seal counts from two neighboring harbours in the Solent region of south England. Generalized additive models showed a significant increase in the numbers of harbour (mean 5.3–30.5) and grey (mean 0–12.0) seals utilizing Chichester Harbour. Conversely, in Langstone Harbour there has been a slight decrease in the number of harbour seals (mean 5.3–4.0). Accompanying photographic data from 2016 to 18 supports the increase in seal numbers within Chichester Harbour, with a total of 68 harbour and 8 grey seals identified. These data also show evidence of site fidelity of harbour seals in this area, with almost a quarter of animals resighted within the past three years. Overall, this long‐term study indicates an increasing number of both harbour and grey seals within the Solent. However, more research is required to identify the drivers of this trend.

Harbour seals (Phoca vitulina) and grey seals (Halichoerus grypus) both occur within the UK, but display regional contrasting population trends. While grey seals are typically increasing in number, harbour seals have shown varying trends in recent decades following repeated pandemics. There is a need for monitoring of regional and local populations to understand overall trends. This study utilized a 20‐year dataset of seal counts from two neighboring harbours in the Solent region of south England. Generalized additive models showed a significant increase in the numbers of harbour (mean 5.3–30.5) and grey (mean 0–12.0) seals utilizing Chichester Harbour. Conversely, in Langstone Harbour there has been a slight decrease in the number of harbour seals (mean 5.3–4.0). Accompanying photographic data from 2016 to 18 supports the increase in seal numbers within Chichester Harbour, with a total of 68 harbour and 8 grey seals identified. These data also show evidence of site fidelity of harbour seals in this area, with almost a quarter of animals resighted within the past three years. Overall, this long‐term study indicates an increasing number of both harbour and grey seals within the Solent. However, more research is required to identify the drivers of this trend. [ABSTRACT FROM AUTHOR]

Individuals within amphibian populations are commonly identified using artificial marking techniques, such as toe clipping and microchipping. However, many species in this group may be strong candidates for visual identification from photographs given intraspecific variability in skin features. We investigated the potential for dorsal skin patterns to be used as natural markers for the photo‐identification of both juveniles and adults of the green and golden bell frog (Litoria aurea). This is a threatened species that has come under intense population monitoring using capture‐mark‐recapture procedures primarily involving the use of artificial markers, with no apparent investigation of the potential for natural markers to be used instead. We collected photographs of marked individuals to determine the level of intraspecific variability in dorsal patterning within a population. This photo‐database was subsequently used to create an online survey in which participants were asked to match separate images of query frogs from small image pools by comparing dorsal patterns. Photographs were taken on a smartphone device under field conditions to test whether this technique could be applied to the study of wild populations with little cost or expertise required. We showed that dorsal patterns are clear and distinct among L. aurea individuals and easily visualised from field‐acquired images to detect recapture events by eye with a low error rate. While an overwhelming majority of adults possessed dorsal patterning that can be easily distinguished by eye, juveniles often showed a complete absence of patterning, suggesting that photo‐identification may be more effective for adult stages. Nevertheless, we highlight the feasibility of collecting visual information on the natural markings of a threatened anuran, providing evidence that it may be used as a supplementary form of identification alongside more traditional techniques, highlighting a potential direction for the future monitoring of this species. [ABSTRACT FROM AUTHOR]

Indo‐Pacific humpback dolphins (Sousa chinensis) inhabit shallow coastal waters of the Indo‐Pacific region including southeast China, with at least 6 putative populations identified to date in Chinese waters. However, the connectivity among these populations has not yet been fully investigated. In the present study, we compared and cross‐matched photographic catalogs of individual dolphins collected to date in the Pearl River Delta region, Leizhou Bay, Sanniang Bay, and waters southwest of Hainan Island, a total of 3158 individuals, and found no re‐sighting of individual dolphins among the 4 study areas. Furthermore, there was a notable difference in the pigmentation pattern displayed by individuals from these 4 regions. We suggest that this may be a phenotypical expression of fine‐scale regional differentiation among humpback dolphin groups, possibly distinct populations. Given the considerable conservation management implications it may carry (e.g. definition of management units), further research is much needed. [ABSTRACT FROM AUTHOR]

Peru is probably home to the largest population of Andean bears (Tremarctos ornatus; Peyton 1999); however, no studies have assessed the density and ecology of the species in this region in the past 20 years. Population density estimates are a cornerstone of species conservation because they help guide decision-making and monitoring of species trends. Here, we study Andean bear population density in a small area (i.e., visible area: 352 ha), Copal, in the Amazonas region in Peru between 2015 and 2017. To estimate Andean bear density, we used 3 methods: one based on capture-recapture data of bears, one based on an occupancymodel, and one based on the frequency of a uniquely colored bear compared with the frequency of other black Andean bears. Our results estimated Andean bear densities between 8.85 and 17.39 bears/100 km²; we considered our estimate of 10.38 bears/100 km² from capture-recapture data to be the most reliable. We also recalculated Andean bear density results from Ecuador by Molina et al. (2017), which provided a similar estimate of 11.49 bears/100 km². Additionally, we report a unique finding of a bear with a golden brown pelage, which we suspect to be the first case in Andean bears. During behavioral observations, Andean bears were predominantly feeding. We suggest that, although Andean bears have large home ranges, a few small areas may be of disproportionate importance to a population. Protecting small areas frequently used by a large number of bears could be an effective mean for Andean bear conservation where large reserves are not a feasible option. We also recognize the need for large-scale studies using a spatial capture-recapture framework, and to associate the results of Andean bear density with resource use in order to successfully protect high-value Andean bear habitat. [ABSTRACT FROM AUTHOR]

Population studies often incorporate capture‐mark‐recapture (CMR) techniques to gather information on long‐term biological and demographic characteristics. A fundamental requirement for CMR studies is that an individual must be uniquely and permanently marked to ensure reliable reidentification throughout its lifespan. Photographic identification involving automated photographic identification software has become a popular and efficient noninvasive method for identifying individuals based on natural markings. However, few studies have (a) robustly assessed the performance of automated programs by using a double‐marking system or (b) determined their efficacy for long‐term studies by incorporating multi‐year data. Here, we evaluated the performance of the program Interactive Individual Identification System (I3S) by cross‐validating photographic identifications based on the head scale pattern of the prairie lizard (Sceloporus consobrinus) with individual microsatellite genotyping (N = 863). Further, we assessed the efficacy of the program to identify individuals over time by comparing error rates between within‐year and between‐year recaptures. Recaptured lizards were correctly identified by I3S in 94.1% of cases. We estimated a false rejection rate (FRR) of 5.9% and a false acceptance rate (FAR) of 0%. By using I3S, we correctly identified 97.8% of within‐year recaptures (FRR = 2.2%; FAR = 0%) and 91.1% of between‐year recaptures (FRR = 8.9%; FAR = 0%). Misidentifications were primarily due to poor photograph quality (N = 4). However, two misidentifications were caused by indistinct scale configuration due to scale damage (N = 1) and ontogenetic changes in head scalation between capture events (N = 1). We conclude that automated photographic identification based on head scale patterns is a reliable and accurate method for identifying individuals over time. Because many lizard or reptilian species possess variable head squamation, this method has potential for successful application in many species. [ABSTRACT FROM AUTHOR]

Range expansions and increases in the frequency of killer whale (Orcinus orca) sightings have been documented in the eastern Canadian Arctic, presumably the result of climate change‐related sea‐ice declines. However, the effects of increased predator occurrence on this marine ecosystem remain largely unknown. We explore the consequences of climate change‐related range expansions by a top predator by estimating killer whale abundance and their possible consumptive effects on narwhal (Monodon monoceros) in the Canadian Arctic. Individual killer whales can be identified using characteristics such as acquired scars and variation in the shape and size of their dorsal fins. Capture–mark–recapture analysis of 63 individually identifiable killer whales photographed between 2009 and 2018 suggests a population size of 163 ± 27. This number of killer whales could consume >1,000 narwhal during their seasonal residency in Arctic waters. The effects of such mortality at the ecosystem level are uncertain, but trophic cascades caused by top predators, including killer whales, have been documented elsewhere. These findings illustrate the magnitude of ecosystem‐level modifications that can occur with climate change‐related shifts in predator distributions. [ABSTRACT FROM AUTHOR]

When the Omura’s whale (Balaenoptera omurai) was first described in 2003, it was known from only three locations: the southern Sea of Japan, and the vicinities of the Cocos (Keeling) Islands and Solomon Islands. Work over the following decade suggested a range limited to the eastern Indo-Pacific, but more recent discoveries in the western Indian Ocean and Atlantic Ocean suggested a more widespread range than previously thought. Here we use all available sources of information, including published papers, unpublished reports, and internet-based accounts, substantiated through genetic, morphological, photographic and acoustic documentation, to compile accounts of Omura’s whales globally. Reports increased precipitously since 2015 after publication of the first detailed external description of the species, reflecting the impact of the recently elevated awareness of the species. We report 161 accounts from 95 locales in the waters of 21 range states, and found that the species is widely distributed in primarily tropical and warm-temperate locations. Currently it is known from all ocean basins with the exception of the central and eastern Pacific. The majority of accounts remain in the eastern Indo-Pacific suggesting a potentially recent range expansion from this region. There is a strong tendency toward a coastal and neritic distribution, although there are also several pelagic records. A predominantly near-coastal distribution places Omura’s whale at risk from anthropogenic activities throughout its range, and its tropical distribution in often remote and poorly monitored areas makes adequately documenting and assessing threats challenging. We assess documented threats in light of the reported species’ range, and found threats from, at minimum, ship strikes, fisheries bycatch and entanglement, local directed hunting, petroleum exploration (seismic surveys), and coastal industrial development. Current evidence indicates that at least some populations are non-migratory with local, potentially restricted ranges. Furthermore, there is low genetic diversity documented throughout its global distribution. Given the species may be characterized by small local populations, it may be particularly vulnerable to impacts from existing regional anthropogenic threats. We recommend that focused work be conducted to locate and study local populations, assess potential population isolation, and determine conservation status and specific anthropogenic threats across the species’ range.

Matching two different images of an unfamiliar face is difficult, although we rely on this process every day when proving our identity. Although previous work with laboratory photosets has shown that performance is error-prone, few studies have focussed on how accurately people carry out this matching task using photographs taken from official forms of identification. In Experiment 1, participants matched high-resolution, colour face photos with current UK driving licence photos of the same group of people in a sorting task. Averaging 19 mistaken pairings out of 30, our results showed that this task was both difficult and error-prone. In Experiment 2, highresolution photographs were paired with either driving licence or passport photographs in a typical pairwise matching paradigm. We found no difference in performance levels for the two types of ID image, with both producing unacceptable levels of accuracy (around 75%-79% correct). The current work benefits from increased ecological validity and provides a clear demonstration that these forms of official identification are ineffective and alternatives should be considered. [ABSTRACT FROM AUTHOR]

The estimation of demographic parameters in wild populations is strengthened by individual identification. For amphibians, various techniques are used to either temporarily or permanently mark individuals for identification. Photo-identification of body patterns offers a non-invasive technique. However, the reliability of photo-recognition software is key to the reliable estimation of the true demographic parameters. In the current study, we assessed the effectiveness of fully-automated and semi-automated software: Wild-ID and APHIS. We used the cryptic salamander Hydromantes strinatii as our study species. We used the False Rejection Rate (FRR) of Top 1, Top 5 and Top 10 matches of chest and cloaca pictures. Finally, we assessed the bias induced by our FRR for the estimation of population size through simulation. Wild-ID FRRs ranged from 0.042 to 0.093 while APHIS' ranged from 0.227 to 0.547. Wild-ID was equally efficient with pictures from the chest and from the cloaca, while APHIS was significantly more efficient with chest pictures than cloaca pictures. Cropping pictures did not significantly improve Wild-ID effectiveness. Our Wild-ID FRRs are among the lowest ever obtained from pictures of an amphibian with a complex chromatophore pattern. Simulation showed that the Top 10 FRR from selected software Wild-ID induced a low bias 2.7% on the estimation of population size. The effectiveness and plasticity of Wild-ID provides opportunities for reliably monitoring amphibian species with complex colour patterns. [ABSTRACT FROM AUTHOR]

This study presents the first robust estimates of abundance and demographic parameters of common bottlenose dolphins (Tursiops truncatus) in a highly affected coastal ecosystem along the north-eastern Atlantic. Seasonal abundance, apparent survival and temporary emigration rates were estimated using Pollock's robust design models. Photographic identification data were collected from 2014 to 2016 along the north-western Iberian coast (Spain). Bottlenose dolphins were present year-round and with a high degree of occurrence in the study area, which is highly affected by human activity but is also a highly productive coastal ecosystem. Local abundance of bottlenose dolphins ranged from 56 in autumn 2014 to 144 in winter 2015. Apparent survival rate was high and constant, indicating no mortality and no permanent emigration. Temporal emigration rates varied seasonally and were lower from autumn to winter, suggesting that dolphins had a high probability of returning during the winter period. The observed changes in abundance and emigration rates most likely reflect seasonal fluctuations in abundance of prey species in this area. These results provide important baseline information in an area subject to significant anthropogenic pressures and for future comparisons with other populations of similar characteristics under the pressure of human activities, such as fisheries and aquaculture. [ABSTRACT FROM AUTHOR]

When dealing with large marine species, individual photographic identification plays a very important part in capture-mark-recapture studies. The success of this method is determined by the consistent correct identification of individuals, but as the number of images in the database increases, the task becomes increasingly time-consuming, affecting the accuracy of the matches. Although a few software packages are available, universally applied methods remain problematic in long-term studies, suggesting the need for species-specific software. This study presents new image recognition software tested on white sharks’ dorsal fins and is based on a dynamic time warping algorithm. The software is specifically designed to improve the matching success of individuals, to standardise the data collection and to increase the overall accuracy when managing a large capture-mark-recapture database. [ABSTRACT FROM AUTHOR]

Photographic capture-recapture is a valuable tool for obtaining demographic information on wildlife populations due to its noninvasive nature and cost-effectiveness. Recently, several computer-aided photo-matching algorithms have been developed to more efficiently match images of unique individuals in databases with thousands of images. However, the identification accuracy of these algorithms can severely bias estimates of vital rates and population size. Therefore, it is important to understand the performance and limitations of state-of-the-art photo-matching algorithms prior to implementation in capture-recapture studies involving possibly thousands of images. Here, we compared the performance of four photo-matching algorithms; Wild- ID, I3S Pattern+, APHIS, and AmphIdent using multiple amphibian databases of varying image quality. We measured the performance of each algorithm and evaluated the performance in relation to database size and the number of matching images in the database. We found that algorithm performance differed greatly by algorithm and image database, with recognition rates ranging from 100% to 22.6% when limiting the review to the 10 highest ranking images. We found that recognition rate degraded marginally with increased database size and could be improved considerably with a higher number of matching images in the database. In our study, the pixel-based algorithm of AmphIdent exhibited superior recognition rates compared to the other approaches. We recommend carefully evaluating algorithm performance prior to using it to match a complete database. By choosing a suitable matching algorithm, databases of sizes that are unfeasible to match 'by eye' can be easily translated to accurate individual capture histories necessary for robust demographic estimates. [ABSTRACT FROM AUTHOR]

Rationale: Zebrafish have a sophisticated color- and shape-sensitive visual system, so we examined color cue-based novel object recognition in zebrafish. We evaluated preference in the absence or presence of drugs that affect attention and memory retention in rodents: nicotine and the histone deacetylase inhibitor (HDACi) phenylbutyrate (PhB). Objectives: The objective of this study was to evaluate whether nicotine and PhB affect innate preferences of zebrafish for familiar and novel objects after short- and long-retention intervals. Methods: We developed modified object recognition (OR) tasks using neutral novel and familiar objects in different colors. We also tested objects which differed with respect to the exploratory behavior they elicited from naïve zebrafish. Results: Zebrafish showed an innate preference for exploring red or green objects rather than yellow or blue objects. Zebrafish were better at discriminating color changes than changes in object shape or size. Nicotine significantly enhanced or changed short-term innate novel object preference whereas PhB had similar effects when preference was assessed 24 h after training. Analysis of other zebrafish behaviors corroborated these results. Conclusions: Zebrafish were innately reluctant or prone to explore colored novel objects, so drug effects on innate preference for objects can be evaluated changing the color of objects with a simple geometry. Zebrafish exhibited recognition memory for novel objects with similar innate significance. Interestingly, nicotine and PhB significantly modified innate object preference. [ABSTRACT FROM AUTHOR]

Adult survival is a primary determinant of abundance and dynamics of large herbivore populations. For species that are inconspicuous, however, accurate survival estimation depends on accommodating low detection probability. For species with individually recognizable markings, photographic capture-recapture ( CR) provides an approach to estimate population parameters while accounting for imperfect detection. I investigated the use of photographic CR for a cryptic large herbivore, the nyala, in a region of Hluhluwe- iMfolozi Park, South Africa. I conducted photographic sampling based on the closed robust design, with 5-6 daily sampling occasions nested within three week-long sampling periods, which delineated one dry and one wet season. Detection differed between sexes: encounter probability of female adults depended on whether individuals fell into high-encounter (seasonal range: 0.61-0.71) or low-encounter (seasonal range: 0.29-0.40) groups, whereas male adults had a constant encounter probability of 0.39 per day. For both sexes, monthly survival probability was ≥0.93 and did not differ appreciably between seasons or sexes. Given the role of survival in population dynamics, photographic CR has the potential to provide survival estimates for cryptic large herbivores that lack such information. [ABSTRACT FROM AUTHOR]

Needlefishes (Beloniformes) were observed employing a range of stalking and attacking behaviours to attack schools of bait fishes ranging from the use of tactics common to predatory fishes to a novel behaviour: the use of leaping, aerial attacks. These aerial attacks are suggested to serve two purposes: to extend the attack range of the needlefishes and to reduce their prey's potential for evasion. Furthermore, a third purpose is hypothesized that the needlefishes are taking advantage of Snell's Window, an optical effect which may mask their approach to their prey. [ABSTRACT FROM AUTHOR]

Amphibian populations are in decline worldwide. Monitoring programas are important, but many studies use invasive techniques to handle, mark, and identify individuals. We recommend a noninvasive technique in which individuals can be identified from photographs basedon individual markings for capture-recapture analyses. As a case study, we examined the population dynamics of dendrobates auratus at a highly altered habitat in northern Costa Rica. We applied the robust design to the capture-recapture data from the photographs of individual frogs at two 25-m transects, a parking lot and a gravel walkway. From these data, we estimated parameters for survival, emigration, immigration,abundande, and capture probability. The observed mean density estimate of 2.62+-0.60 individuals (CI=1-4) per 100 m2 is the first statistically rigorous estimate for this species in altered habitats. These results suggest that this species might be suited to occur in human-altered habitats and may be less susceptible to population declines than previously suggested.Our noninvasive methodology to obtain robust abundance and demographic parameter estimates is also applicable to citizen-science surveys for a variety of taxa of amphibians and reptiles that are individually identifiable.

The reef manta ray Manta alfredi aggregates at several sites along the east coast of Australia. Photographic identification and mark-recapture methods were used to report on the site affinity, size and structure of this population of M. alfredi. A total of 716 individuals were identified in 1982-2012, including 636 at Lady Elliot Island (LEI), southern Great Barrier Reef. Over 60 % of individuals identified were resighted at least once during the study period. Multiple resightings within and among years imply a high degree of site affinity by individuals to aggregation sites. One individual was sighted 11 times at LEI over a 30-yr period. The sex ratio of this population was significantly biased towards females (1.2:1 female-to-male ratio), and females were more commonly resighted than males. Robust design population models were used to estimate the population size of the winter aggregation at LEI over a 4-yr period. The models estimated up to 456 (95 % CI 399-535) M. alfredi individuals in the population within one winter season and a high annual apparent survival. This study demonstrated that waters around LEI form a key aggregation site for a large portion of the M. alfredi population in east Australian waters. [ABSTRACT FROM AUTHOR]

Volunteers were able to match photographs of the same common carp Cyprinus carpio taken on two occasions. Images were identified correctly on 95·76% of occasions. Thus, scale patterns can be used for non-invasive identification of C. carpio over a period of time. [ABSTRACT FROM AUTHOR]

We investigated whether acutely induced anxiety modifies the ability to match photographed faces. Establishing the extent to which anxiety affects face-matching accuracy is important because of the relevance of face-matching performance to critical security-related applications. Participants (N = 28) completed the Glasgow Face Matching Test twice, once during a 20-min inhalation of medical air and once during a similar inhalation of air enriched with 7.5% CO2, which is a validated method for inducing acute anxiety. Anxiety degraded performance, but only with respect to hits, not false alarms. This finding provides further support for the dissociation between the ability to accurately identify a genuine match between faces and the ability to identify the lack of a match. Problems with the accuracy of facial identification are not resolved even when viewers are presented with a good photographic image of a face, and identification inaccuracy may be heightened when viewers are experiencing acute anxiety. [ABSTRACT FROM AUTHOR]

Indo-Pacific Humpback Dolphins Sousa chinensis (Humpback Dolphins hereafter) are listed as 'near threatened' on an international level and 'migratory' in Australian waters. There is limited information on Humpback Dolphins in Western Australian State waters, where the species remains unlisted. This lack of knowledge hinders the management and conservation of the species in a region of rapidly increasing coastal development. We conducted opportunistic boat-based surveys in April 2010 and present data on the location, size and composition of Humpback Dolphin groups encountered in the near-shore waters around the North West Cape, Western Australia. A total of 42 groups were encountered in a variety of habitats during 145 h on the water over ca. 80 km coastline. Group size ranged from 1 to 15, with a mean (± SE) of 5.3 (± 0.48) individuals. A total of 54 Humpback Dolphins were identified from photographs of the unique markings on their dorsal fins. The lack of a plateau in the cumulative discovery curve of identified individuals over the duration of the study suggests that only a subset of dolphins in the area was identified. This region is close to the south-western limit of the species' Australian distribution and appears to represent an important location for Western Australian Humpback Dolphins. In light of increasing anthropogenic activity around the North West Cape and Exmouth Gulf, these preliminary findings from a limited survey effort indicate that further research into this population is required. [ABSTRACT FROM AUTHOR]

Abstract: A photo-identification method was developed to recognise individual Protoreaster nodosus, a large sea star widely distributed in the Indo-Pacific region. Digital photographs of the aboral surface of P. nodosus individuals were obtained from intertidal populations in Singapore between 2002 and 2010. Each photograph was given a numerical code based on the colouration of arm tips, the condition of the arms and the number of tubercles, comprising a total of 17 independent characters, or 27 for developing individuals. Photographs with similar codes were grouped together using a computer and then matched by eye to confirm if they were from the same individual. Natural characteristics not included in the code, such as the arrangement of tubercles and pigmentation pattern, were also used in the recognition process. The natural markings selected were discrete characters that are easily quantified. Based on the variations observed in 4842 photographs of 1817 individuals over 9years, the coding system has the potential of identifying up to 4.24×1021 individuals. The extensive range of natural marks used in the code also ensures that individuals can be re-identified even when some natural marks have become modified due to injury or growth. The code generally remained stable for 2–3years for each individual, and lasted up to 9years in some individuals. The reliability of the photo-identification method was verified by blind studies using temporary tags. This photo-identification method allows the implementation of long-term mark–recapture studies on sea stars, which are currently lacking due to the difficulties in tagging or marking sea stars in the field. [Copyright &y& Elsevier]

The use of photography to discriminate between individuals in a population using natural markings or aberrations is increasingly being utilized to support field research on elasmobranchs. This non-intrusive method has facilitated investigation of a wide variety of subjects including population composition, abundance estimates, residency and movement, demography and social behaviours. Here the first detailed review of photo-identification as a research technique for sharks and rays is provided, and its assumptions, current applications and potential highlighted. The limitations and practical considerations of photographic studies are also investigated with recommendations on initial survey design and ongoing data collection using current technology. Future directions are also explored with an emphasis on a move towards standardized approaches and automated recognition programmes to facilitate global collaborative work. [ABSTRACT FROM AUTHOR]

Photo-identification and conventional tagging were used to estimate population size and structure of the whale shark Rhincodon typus near Holbox Island, Mexico. From 2005 to 2008, photographs of spot patterns behind the last gill slit and in a lateral view on the left side of each animal were used to identify individuals. Additionally, 578 R. typus were tagged using conventional marker tags. Of these and the 350 R. typus that were identified from 1184 photographs, 65% were male; 27%, female and 8%, indeterminate sex. Photographed R. typus ranged in size from 2·5 to 9·5 m total length. Size was bimodal with a large peak at 6 m and a smaller peak at 7 m. Photo-identification showed that there was considerable loss of marker tags. Few of these remained on the animals for more than a year, so that interannual re-sights using tagging could not be used in population modelling. Forty six interannual re-sightings were found in the photographic library; the interval between these re-sightings was typically 1 year. It was estimated that the R. typus aggregation near Holbox Island ranged from 521 to 809 individuals, based on mark-recapture models. From 13 to 33% of R. typus photographed had scars that were attributable to boat strikes. This study provides a baseline for assessing the status of R. typus near Holbox Island. This information is useful to understand drivers of local population size and distribution and potential concerns about increasing effects of tourism on R. typus in this area and for designing better management programmes for R. typus conservation. [ABSTRACT FROM AUTHOR]

Although the whale shark Rhincodon typus is the largest extant fish, it was not described until 1828 and by 1986 there were only 320 records of this species. Since then, growth in tourism and marine recreation globally has lead to a significant increase in the number of sightings and several areas with annual occurrences have been identified, spurring a surge of research on the species. Simultaneously, there was a great expansion in targeted R. typus fisheries to supply the Asian restaurant trade, as well as a largely un-quantified by-catch of the species in purse-seine tuna fisheries. Currently R. typus is listed by the IUCN as vulnerable, due mainly to the effects of targeted fishing in two areas. Photo-identification has shown that R. typus form seasonal size and sex segregated feeding aggregations and that a large proportion of fish in these aggregations are philopatric in the broadest sense, tending to return to, or remain near, a particular site. Somewhat conversely, satellite tracking studies have shown that fish from these aggregations can migrate at ocean-basin scales and genetic studies have, to date, found little graphic differentiation globally. Conservation approaches are now informed by observational and environmental studies that have provided insight into the feeding habits of the species and its preferred habitats. Notwithstanding these advances, there remain notable gaps in the knowledge of this species particularly with respect to the life history of neonates and adults who are not found in the feeding aggregations. [ABSTRACT FROM AUTHOR]

Despite coelacanths, Latimeria chalumnae, being listed as either endangered by CITES or critically endangered by the IUCN, their population size within South Africa is unknown and still needs to be estimated. Their conservation status unfortunately excludes the use of conventional tagging to mark individual animals for a possible mark–recapture experiment. This study shows that because coelacanths have a unique spot patterning it is possible to quickly and accurately identify specific individuals photographically using computer-aided identification software. Without any manual intervention by an operator, the software accurately identified between 56 and 92% of the individuals. Indentification success increased to 100% if the operator could also manually select from other potential matching photographs. It was also shown that fish exhibiting a yaw angle not exceeding 60° could be accurately identified in photographs, although the percentage of fish correctly identified without operator-intervention decreased rapidly with increasing yaw angle. Computer-aided identification should therefore facilitate future coelacanth research as it is both efficient and accurate while also reducing potential stress on the animals observed. [ABSTRACT FROM AUTHOR]

Abstract: Occurrence and behaviour of Paromola cuvieri (Crustacea, Decapoda) were recorded by means of the MEMO lander equipped with two digital cameras and deployed in the cold-water coral community of the Santa Maria di Leuca (Mediterranean Sea). A total of 14 individuals were observed at depths between 547 and 648m; 10 in the coral habitat on coral mounds and 4 off the coral habitat on muddy bottoms. Thirteen specimens recorded were females, one male and all were shown to scavenge the bait. All the specimens carried a sponge on their exoskeleton using the fifth pereiopods. The specimens were distinguishable by the size and shape of the carried sponge. The present observations demonstrate both passive covering behaviour and active behaviour of discouraging approach and attack from competitors or predators, respectively. This study represents the first in situ documentation of Paromola cuvieri behaviour interacting with other deep-sea species in the Mediterranean Sea. [Copyright &y& Elsevier]

The article focuses on a study about the community structure and abundance of bottlenose dolphins or Tursiops truncatus found in the coastal waters of the northeast coastal waters of the Gulf of Mexico. It notes that baseline photo-identification (ID) surveys and mark-recapture surveys have been used to determine the community structure and the abundance of the bottlenose dolphins living within the region. Findings show that two parapatric communities of bottlenose dolphins exist in the St. Vincent Sound to Alligator Harbor (SVS-AH) in Florida. It adds that communities tend to differ in terms of structure and abundance in which the eastern survey area holds a population that is largely transient while the western survey area holds dolphins that observe higher site-fidelity patterns.

Forty-three individual adult weedy seadragons Phyllopteryx taeniolatus were identified from underwater images using patterns of spots and blotches on the lateral surface of the abdomen. These patterns were unique and did not change over the 18 month course of the study and could therefore be used to identify individuals when estimating population variables using non-invasive capture-mark-recapture and accumulation curve methods. Two similar neighbouring sites in southern Tasmania showed considerable differences in their estimated populations of P. taeniolatus. Estimated annual survival was >80% at one site suggesting that P. taeniolatus may be considerably longer lived than other syngnathids with a maximum life span in excess of 10 years. Males incubating embryos were observed from October to March and at least two clutches could be borne during this period. This technique of photo-identification could provide a cheap and effective way to monitor populations of this iconic species across its range, particularly in conjunction with optimized pattern-recognition software. [ABSTRACT FROM AUTHOR]

Despite the increasing tourism interest worldwide for the manta ray, Manta alfredi, very little is known about its biology and ecology. Knowledge of its distribution and movement patterns is important for conservation purposes. Here we describe the distribution, site visitation and movements of M. alfredi along the east coast of Australia. Photographic identification techniques were used to identify individual manta rays at three study sites: Lady Elliot Island, North Stradbroke Island and Byron Bay. Of 388 M. alfredi individuals identified at Lady Elliot Island, 187 (48%) were subsequently re-identified at least once at the same site. In total, 31 individuals were identified at both Lady Elliot Island and North Stradbroke Island (~380km to the south) and 4 at both Lady Elliot Island and Byron Bay (~500km to the south). Manta alfredi was present all year around at Lady Elliot Island, although in higher numbers in winter, and was mainly observed at North Stradbroke Island and Byron Bay from mid-spring to mid-autumn. This is the first report of seasonal movements and site affinity for M. alfredi in eastern Australian waters and emphasises the value of photographic identification for monitoring the occurrence of individuals. [ABSTRACT FROM AUTHOR]

Misidentification of animals is potentially important when naturally existing features (natural tags) such as DNA fingerprints (genetic tags) are used to identify individual animals. For example, when misidentification leads to multiple identities being assigned to an animal, traditional estimators tend to overestimate population size. Accounting for misidentification in capture-recapture models requires detailed understanding of the mechanism. Using genetic tags as an example, we outline a framework for modeling the effect of misidentification in closed population studies when individual identification is based on natural tags that are consistent over time (non-evolving natural tags). We first assume a single sample is obtained per animal for each capture event, and then generalize to the case where multiple samples (such as hair or scat samples) are collected per animal per capture occasion. We introduce methods for estimating population size and, using a simulation study, we show that our new estimators perform well for cases with moderately high capture probabilities or high misidentification rates. In contrast, conventional estimators can seriously overestimate population size when errors due to misidentification are ignored. [ABSTRACT FROM AUTHOR]

Photographic identification is a promising marking technique alternative to the toe-clipping, since it is completely harmless, cheap, and it allows long time identification of individuals. Its application to ecological studies is mainly limited by the time consuming to compare pictures within large datasets and the huge variation of ornamentation patterns among different species, which prevent the possibility that a single algorithm can effectively work for more than few species. Scales of Reptiles offer an effective alternative to ornamentations for computer aided identification procedures, since both shape and size of scales are unique to each individual, thus acting as a fingerprint like ornamentation patterns do. We used the Interactive Individual Identification System (I3S) software to assess whether different individuals of two species of European lizards (Podarcis muralis and Lacerta bilineata) can be reliably photographically identified using the pattern of the intersections among pectoral scales as fingerprints. We found that I3S was able to identify different individuals among two samples of 21 individuals for each species independently from the error associated to the ability of the operators in collecting pictures and in digitizing the pattern of intersections among pectoral scales. In a database of 1043 images of P. muralis collected between 2007 and 2008, the software recognized 98% of recaptures within each year, and 99% of the recaptures between years. In addition, 99% and 96% of matches were ranked among the top five, and no more than 5 minutes were needed for digitizing and processing each image. The lepidosis of reptiles is a reliable alternative to ornamentation patterns in photographic identification of reptiles, which can be effectively analysed using the I3S software. This result represents a significant improvement in photographic identification of reptiles since (i) this procedure can be easily extended to most other species of reptiles, (ii) all kind of individuals within a species can be marked (i.e., young, subadults and adults) despite the differences in ornamentation patterns, and (iii) it is the only technique for species, like the western green lizard, which lack a clear ornamentation pattern. [ABSTRACT FROM AUTHOR]

Misidentification of animals is potentially important when naturally existing features (natural tags) are used to identify individual animals in a capture-recapture study. Photographic identification (photoID) typically uses photographic images of animals' naturally existing features as tags (photographic tags) and is subject to two mare causes of identification errors: those related to quality of photographs (non-evolving natural tags) and those related to changes in natural marks (evolving natural tags). The conventional methods for analysis of capture-recapture data do not account for identification errors, and to do so requires a detailed understanding of the misidentification mechanism. Focusing on the situation where errors are due to evolving natural tags, we propose a misidentification mechanism and outline a framework for modeling the effect of misidentification in closed population studies. We introduce methods for estimating population size based on this model. Using a simulation study, we show that conventional estimators can seriously overestimate population size when errors due to misidentification are ignored, and that, in comparison, our new estimators have better properties except in cases with low capture probabilities (<0.2) or low misidentification rates (<2.5%). [ABSTRACT FROM AUTHOR]

Monitoring the dynamics and status of populations of harbor seals (Phoca vitulina richardii) requires efficient methods for estimating population parameters from mark--resight data. We used a test set of photographs from 182 individuals identified by flipper tags, scars, or unique pelage markings to test whether individuals could be identified accurately by their ventral pelage markings; to document efficiency and misidentification error rate associated with a computer-assisted photograph-matching system; and to test for bias in mark-recapture survival estimates resulting from misidentification errors. Pelage patterns of seals that were not of dark-intermediate or intermediate color phase were unique and stable from birth until 6-8 years, and from year to year as adults. The computer-assisted system greatly improved efficiency of photograph matching: 93.3% of good photographs and 69.9% of all photographs ranked 1st, and 95.2% of good photographs ranked in the top 0.3% of the ordered list for visual checking. Additional visual matching error averaged <3.0% for good photographs, and overall misidentification error rate was low at 1.8%, due to the availability of multiple photographs for matching. Inclusion of poor-quality photographs reduced ranking success by ~20% and increased additional visual matching error up to 20%. Bias in survival estimates was -7.0% for a misidentification rate of 8.8%, but was ≤1.1% for misidentification rates of <2.7%, achieved by restricting data to only good photos. Our study suggests that estimation of misidentification error rate, inclusion of only high-quality photographs, or use of models that account for misidentification error, are required to prevent bias in mark-recapture survival estimates when using data from natural-marking studies. [ABSTRACT FROM AUTHOR]

In order to accurately assess the status of the cheetah Acinonyx jubatus it is necessary to obtain data on numbers and demographic trends. However, cheetahs are notoriously difficult to survey because they occur at very low population densities and are often shy and elusive. In South Africa the problem is further complicated in areas where land is privately owned, restricting access, with dense bush and cheetahs that are frequently persecuted. Cheetahs are individually identifiable by their unique spot patterns, making them ideal candidates for capture-recapture surveys. Photographs of cheetahs were obtained using four camera traps placed successively at a total of 12 trap locations in areas of known cheetah activity within a 300 km² area in the Thabazimbi district of the Limpopo Province. During 10 trapping periods, five different cheetahs were photographed. These results were used to generate capture histories for each cheetah and the data were analysed using the capture--recapture software package CAPTURE. Closure tests indicated that the population was closed ( P= 0.056). The Mh model was used to deal with possible heterogeneous capture probabilities among individual cheetahs. Closure tests did not reject the model assumption of population closure ( P = 0.056). The Mh model produced a capture probability of 0.17 with an estimate of 6-14 cheetahs ( P = 0.95) and a mean population size of seven cheetahs (S.E. = 1.93). These results are promising and will be improved with employment of more camera traps and sampling a larger area. [ABSTRACT FROM AUTHOR]

Capture-recapture estimates of abundance using photographic identification data are sensitive to the quality of photographs used and distinctiveness of individuals in the population. Here analyses are presented for examining the effects of photographic quality and individual animal distinctiveness scores and for objectively selecting a subset of data to use for capture-recapture analyses using humpback whale ( Megaptera novaeangliae) data from a 2-year study in the North Atlantic. Photographs were evaluated for their level of quality and whales for their level of individual distinctiveness. Photographic quality scores had a 0.21 probability of changing by a single-quality level, and there were no changes by two or more levels. Individual distinctiveness scores were not independent of photographic quality scores. Estimates of abundance decreased as poor-quality photographs were removed. An appropriate balance between precision and bias in abundance estimates was achieved by removing the lowest-quality photographs and those of incompletely photographed flukes given our assumptions about the true population abundance. A simulation of the selection process implied that, if the estimates are negatively biased by heterogeneity, the increase in bias produced by decreasing the sample size is not more than 2%. Capture frequencies were independent of individual distinctiveness scores. [ABSTRACT FROM AUTHOR]