Search

The population structure of humpback whales (Megaptera novaeangliae) in the North Pacific has received significant attention in recent years through the collaborative Structure of Populations, Levels of Abundance, and Status of Humpback whales in the North Pacific (SPLASH) study. However, the analysis of humpback whales in the western North Pacific Asian population was limited in the SPLASH study, due to small sample size. Much of the Asian population summers off Kamchatka, Russia and spends the winters in breeding grounds in Okinawa and Ogasawara, Japan and the Babuyan Islands in the northern Philippines. Prior studies grouped the Commander Islands feeding ground in Russia, with the eastern Aleutian Islands as part of the central humpback whale stock. This paper uses additional years of photo-ID data from both the Philippines (160 whales from 2000-12) and the Commander Islands (531 whales from 2008-10) to establish a previously unreported migratory connection by matching four animals between the two sites. The new migratory linkage found in the present study suggests that a small portion of humpback whales hypothesised to be migrating to a 'missing' breeding ground in the central North Pacific are actually migrating to the Philippines. However, additional studies on a wider geographical scale are required. [ABSTRACT FROM AUTHOR]

Information on movement and site fidelity is important for conservation and management. Photo-ID of common minke whales (Balaenoptera acutorostrata) was conducted from whalewatching vessels within the coastal waters of Faxaflói (a bay on the southwest coast of Iceland) and Skjálfandi (a bay on the northeast coast) between 2007-10 and 2001-10 respectively, to examine fidelity to the sampling locations and movement between them. Images of 292 individual minke whales were obtained in Faxaflói and 61 in Skjálfandi, with an overall 'annual re-capture proportion' of 23.3% in the former and 16.4% in the latter. Most (about 80%) of the resighted animals in each bay were re-sighted in one year only. The total number of identified whales has increased in both Faxaflói and Skjálfandi Bays since 2007 and 2001 respectively, suggesting the existence of an open population in both bays. One match was found between the two bays, eight years apart; the distance was approximately 600km between southwest and northeast Iceland. This study shows the value of photo-ID studies from platforms of opportunity such as whalewatching vessels. More data are required from broader geographic areas before firm conclusions can be drawn about movements and site fidelity within Icelandic waters. [ABSTRACT FROM AUTHOR]

Information characterising site fidelity and abundance for common bottlenose dolphins (Tursiops truncatus) along the southwest coast of Florida is important for defining stock structure for management purposes. Long-term site fidelity and ranging patterns of bottlenose dolphins in Charlotte Harbor and Pine Island Sound, Florida were investigated using photo-ID data collected during 566 boat-based surveys from 1982 through 2007. Seasonal abundance estimates were generated from seven multi-week field seasons during 2001 through 2006, before and after a major hurricane and red tide event occurred in the area. In total, 1,154 distinctive dolphins were identified up to 34 times each with 84% of individuals resighted on more than one day. Multiple year residency rates were high with 81% of dolphins sighted in at least two years and 30% over ten or more years. Seventy-six percent of individuals with sightings on two or more days were observed in both summer and winter. Of 249 dolphins sighted on ten or more days in the study area, 83% were never observed outside the study area, indicating strong site-fidelity. Two years after a devastating Category 4 hurricane in 2004 and following two years of Karenia brevis harmful algal blooms, 94% of dolphins were observed in the same region within the study area and abundance estimates remained stable. Documenting range and site fidelity patterns of individuals over long periods of time is helpful for characterizing population structure and for examining changes attributable to environmental factors and perturbations such as hurricanes, harmful algal blooms and climate change. [ABSTRACT FROM AUTHOR]

The article presents a collaborative research program which gathered data on Chilean blue whales in Isla Grande de Chiloe, Chile through aerial and marine surveys. The study conducted various methods including spatial analyses with a Global Positioning System (GPS), photo-identification survey and behavioural analyses. Results with sighting per unit effort (SPUE) shows relative abundance of the species in discrete 10 km&sup2, while probability contours were shown by kernel density. It found that the area has been used by blue whales as a feeding ground.

The article presents a study, which examines the movements and summer feeding area of Humpback whales (Megaptera novaeangliae) near the Balleny Islands. The study used two separate analyses for the investigation of movement matches discovered between the Balleny Islands (BI) and EA catalogues and the deficiency of matches between the BI and Oceania (OC). It relates the use of photo-identification (ID) studies, which provide evidence of migratory interchange within OC and EA. It mentions the analysis of whales' frequencies in the three areas based on the estimated sizes of population and catalogues. Results show that Antarctic V waters in the area of Balleny Islands are considered summer feeding area of several whales.

Based on direct observations of free-ranging specimens, the giant manta ray Manta birostris is reported from the Marquesas Islands, the first sighting in French Polynesia. Sightings of its sister species, the reef manta ray Manta alfredi, are also reported at the most easterly location in the Pacific Ocean. Preliminary individual identification as well as notes on their distribution are also reported. [ABSTRACT FROM AUTHOR]

We estimated sex- and age-specific apparent survival of harbor seals (Phoca vitulina richardii) born at Tugidak Island, Alaska, from 2000 to 2007 using mark-recapture models and photographs of ventral pelage markings to identify individuals. Estimates of annual apparent survival (1 - (mortality + emigration)) of females were from 0.05 to 0.10 higher than those of males and were 0.820 for weaning (~1 month) to 1 year, 0.865 for 1-3 years, and 0.929 at 3-7 years. Annual survival of males was 0.717, 0.782, and 0.879 for the same ages. Highest mortality occurred preweaning, with cumulative mortality to 4 weeks of age of 0.259, indicating this is the most vulnerable period for Tugidak harbor seals. Estimates of survival, not biased by misidentification, required that an individual had at least 2 good-quality, matching photographs in the photograph library. The number of photographs available for matching improved resighting probabilities from 0.43 for seals with 2 photographs to 0.69 for seals with 8 photographs, but this heterogeneity did not affect survival estimates. Survival estimates based on photograph-identification data were nearly identical to those based on resightings of flipper-tagged seals using mark-recapture models with a preliminary double-tag-loss estimate of 2.5% per year. Photograph identification of natural pelage markings provides a viable method for estimating vital rates of harbor seals even at large haul-outs (> 1,000 animals) and may be useful for populations of conservation concern that require low disturbance of animals or where capturing sufficient numbers of seals for artificial marking is not feasible. [ABSTRACT FROM AUTHOR]

India's Chambal River hosts the largest population of the critically endangered gharial. Boat-based daylight surveys to date only provide indices of relative abundance, without measures of survey bias or error. No attempt to quantify detection probabilities in these surveys has yet been made, and thus, absolute density estimates of this population remain unknown., We surveyed 75 km of the River Chambal and photographed individual gharials for capture-recapture analysis. The total sampling effort yielded 400 captures. Population closure was supported ( z = −1·48, P = 0·069), and closed-population models were used to estimate abundances., Models were selected using the Akaike Information Criterion ( AIC) index of model fit. The best model estimated 231 ± 32 adult, 83 ± 23 subadult and 89 ± 19 juvenile gharials ( Mean ± SE), respectively, while the model-averaged estimate was 220 ± 28 adult, 76 ± 16 subadults and 93 ± 16 juvenile gharials, respectively., The best model estimated absolute densities of 3·08 ± 0·43, 1·11 ± 0·3 and 1·19 ± 0·25 adult, subadult and juvenile gharials km−1, respectively, while the model-averaged estimate was 2·93 ± 0·37, 1·01 ± 0·21 and 1·24 ± 0·21 adult, subadult and juvenile gharials km−1, respectively, compared with relative densities of 0·94, 0·45 and 0·30 adult, subadult and juvenile gharials km−1, respectively, from boat-based daylight surveys. On the basis of our best model, we suggest a detection probability based correction factor of 3·27, 2·47 and 3·97 to boat-based daylight survey estimates of adult, subadult and juvenile gharials, respectively., Synthesis and applications. Used within the framework of capture-recapture analysis, photoidentification provides a reliable and noninvasive method of estimating population size and structure in crocodilians. We also opine that without determining the current status of gharials, highly intensive strategies, such as the egg-collection and rear-and-release programmes being implemented currently, initiated on the basis of underestimates of population sizes, are unwarranted and divert valuable conservation resources away from field-based protection measures, which are essential in the face of threats like hydrologic diversions, sand mining, fishing and bankside cultivation. [ABSTRACT FROM AUTHOR]

The article focuses on the boat-based surveys of humpback whales around Réunion Island in Mauritius from 2004 to 2010, which is aimed in the collection of photo-identification data. The survey was conducted through 1,530 hours of on-searching effort wherein 724 humpback whale sightings were achieved. The surveys revealed that seasonal variation in humpback whale sightings particularly in the months of July to September. Moreover, the survey also features fluke photographs and the mean residency wherein lagged identification of 25 days was identified. The humpback whales survey also reveal 312 species of humpback whales with 5 individuals being re-sighted.

The objective of this study was to estimate the abundance of Sotalia guianensis in Sepetiba Bay, southeastern Brazil, based on photographic identification of animals. Estimates of population size were obtained using capture-recapture models for a closed population. Photo-identification data were analyzed using a model-fitting approach in the computer programs CAPTURE and MARK, and the Schnabel and Schumacher-Eschmeyer estimators were used to calculate the abundance of individuals with natural marks. These estimates were corrected to include unmarked individuals using data of the proportion of identifiable individuals in this population. During the surveys conducted between April 2006 and April 2007, a total of 9990 photographs of dolphins were taken and, of these, 2567 images were of sufficient quality for analysis; 382 dolphins were identified and catalogued from distinctive nicks and notches on their dorsal fins and, among them, 153 dolphins were photographed on more than one occasion. The resulting abundance estimates, corrected to account for the proportion (0.47) of unmarked dolphins in the population, showed an overlap among estimators ranging from 1004 to 1099 individuals. This is the largest estimated abundance for a population of S. guianensis reported to date using the capture-recapture technique. [ABSTRACT FROM AUTHOR]

The way human activities impact animal populations can depend on social structure, which is important to understand in social species such as cetaceans. We investigated association patterns in Indo-Pacific humpback dolphins ( Sousa chinensis (Osbeck, 1765)) inhabiting the Pearl River Estuary near Lantau Island, Hong Kong, using a 10-year data set for 88 individuals. Our analyses revealed two social communities. Each had its own region of core use, to the north and to the west of the island, but their overall ranges partially overlapped northwest of Lantau. The northern community had a fission-fusion structure characterized by short-term associations, while the western community had more long-term associations. Mixed-community groups included calves more often than exclusive groups, so between-community associations may arise from common habitat usage, by females especially, in the overlap area. Recent range extensions by the northern community into the west are likely a response to habitat destruction north of Lantau. This suggests ease of movement between the north and the west is necessary for northern-community dolphins to access suitable habitat, and gives new concern to construction projects planned for the region. We emphasize our study as an example of how sociobiological information can be important in understanding human impacts on animal populations. [ABSTRACT FROM AUTHOR]

The article presents a study on the level of complexity of models needed to forecast the dispersal of endangered species through matrix habitats. The study used various methods such as the capture-mark-recapture (CMR), simulation methods and analysis of geographic information system (GIS) images. Results caution against the use of a total parsimony approach to determining the movement models' complexity to predict dispersal via matrix.

The article presents a study which used photo-identification data to evaluate population dynamics of bottlenose dolphins. The study used methods of Bayesian statistics, the Jolly-Seber mark-recapture models and Markov Chain Monte Carlo (MCMC) methods. It discusses the social clusters' differential site fidelity which can be common in bottlenose dolphins.

We used mitochondrial and nuclear genetic markers to investigate population structure of common bottlenose dolphins, Tursiops truncatus, around the main Hawaiian Islands. Though broadly distributed throughout the world's oceans, bottlenose dolphins are known to form small populations in coastal waters. Recent photo-identification data suggest the same is true in Hawaiian waters. We found genetic differentiation among (mtDNA ΦST= 0.014-0.141, microsatellite F'ST= 0.019-0.050) and low dispersal rates between (0.17-5.77 dispersers per generation) the main Hawaiian Island groups. Our results are consistent with movement rates estimated from photo-identification data and suggest that each island group supports a demographically independent population. Inclusion in our analyses of samples collected near Palmyra Atoll provided evidence that the Hawaiian Islands are also occasionally visited by members of a genetically distinct, pelagic population. Two of our samples exhibited evidence of partial ancestry from Indo-Pacific bottlenose dolphins ( T. aduncus), a species not known to inhabit the Hawaiian Archipelago. Our findings have important implications for the management of Hawaiian bottlenose dolphins and raise concerns about the vulnerability to human impacts of pelagic species in island ecosystems. [ABSTRACT FROM AUTHOR]

An abundance assessment of bottlenose dolphins (Tursiops truncatus) in the Lower River Shannon candidate Special Area of Conservation (cSAC) was undertaken between July and October 2010 using photo-identification. European Union Member States are obliged to designate SACs for bottlenose dolphins to protect important habitats. The Lower River Shannon is the only cSAC in Ireland for this species. A cumulative total of 273 bottlenose dolphins were photographed during the 12 transects, and from these a total of 116 individual animals were identified. They were categorized as follows: 71 with Severity Grade 1 marks, 21 with Severity Grade 2 marks, and 24 with Severity Grade 3 marks. There were 50 dolphins with permanent marks (Severity Grade 1) recorded on both sides of the dorsal fin, 64 on the left hand side only, and 57 on the right hand side only. There was an overlap, with some dolphins occurring in more than one category. Estimates of abundance were calculated using left side, right side, and both side identifications. The proportion of dolphins with re-identifiable marks (Severity Grade 1 only) ranged from 0.60 to 0.63. The estimated abundance of marked individuals was elevated depending on the estimated proportion of marked individuals in the population to give a final estimate of 107 ± 12, CV = 0.12 (95% CI = 83 to 131). Previous abundance estimates for bottlenose dolphins in the Lower River Shannon cSAC ranged from 114 in 2008 to 140 in 2006; the present estimate was within this range and also within the 95% Confidence Intervals for all surveys carried out to date. This suggests that, within the power of the survey technique, the population of bottlenose dolphins in the Lower River Shannon cSAC is relatively stable. [ABSTRACT FROM AUTHOR]

Facial features appear to be a prominent kinship cue for ascribing relatedness among human individuals. Although there is evidence that adults can detect kinship in unrelated and unfamiliar individual's faces, it remains to be seen whether people already possess the ability when they are young. To further understand the development of this skill, we explored children's ability to detect parent-offspring resemblance in unrelated and unfamiliar faces. To this end, we tested approximately 140 children, aged 5-11, in two photo-matching tasks. We used a procedure that asked them to match one neonate's face to one of three adults' faces (Task 1), or to match one adult's face to one of three neonate's faces (Task 2). Our findings reveal asymmetrical performance, depending on the tasks assigned (performance of Task 2 is stronger than for Task 1), and on the sex of individuals who made up the parent-offspring pair (male parents are better matched with neonates than female parents, and boys are better matched than girls). The picture that emerges from our study is, on one hand, that the ability to detect kinship is already present at the age of five but continues to improve as one gets older, and on the other, that perception of parent-offspring facial resemblance varies according to the appraisers' characteristics. [ABSTRACT FROM AUTHOR]

The article discusses a study which proposes a new classification method for blue whale photo-identification that simplifies the photograph comparison by hand. It says that individual identification of blue whales is based on pigmentation patterns which are observed on animal's flanks. It mentions that the new classification method is based on dorsal fin shapes and pigmentation patterns selected from a minor portion of the flank adjacent to the dorsal fin. Results show that the classification applied to the Baja California catalogue of blue whale photographs indicated the dorsal fin types which were not equally represented.

The article presents a study which describes the calving season and the predation risk of botllenose dolphins in Little Bahama Bank. The study used photo-identification surveys to detect newborn dolphins and the Bayesian model to examine seasonal differences. The study defined a six months summer period which are characterized by water temperatures. Results show that the calving rate peaked in December while shark-bite wounds acquired during a four month within the summer period.

The article focuses on the first record of the commensal barnacle (Xenobalanus globicipitis) on bottlenose dolphins (Tursiops truncatus) in Chile. It says that the occurrences of the barnacle on dorsal fins of bottlenose dolphins in the central Chile was high as compared to the regions of the Pacific Ocean, but lower in comparison to the Atlantic Ocean. It adds that systematic photo-identification survey could show interesting aspects of the dolphin-barnacle ecological interactions.

Despite being a common apex-level predator on coral reefs throughout the tropical Indo-Pacific, surprisingly little is known about whitetip reef shark ( Triaenodon obesus) movements and biology. This study used photo-identification from community-contributed photographs to reveal patterns in movements, reproductive biology, and fisheries interactions in this species that have not been previously revealed through more traditional methods. At least 178 individual sharks were identified, and 26 movements were observed. These included movement distances of up to 26.4 km, movement rates of up to 3.27 km/day (9.8 km in 3 days), and movements that required the transit of a 140 m deep channel. Other animals showed high philopatry, being re-sighted at the same locality on multiple occasions (up to 13 sightings for one individual) over periods of up to 7 years. Females showed higher philopatry than males and were more likely than males to be found at shallow (<10 m depth) localities throughout the year. The proportion of male sightings at shallow localities was significantly higher in April and May than other months of the year, possibly due to males coming into the shallows to mate with females. A peak in sightings of late-term females followed by an abrupt decline suggests that pupping season is May into early June, and two females were observed pregnant in consecutive years despite evidence that the gestation period is approximately 1 year for this species. Nine percent of animals carried fishing tackle or exhibited jaw injuries associated with fishery interactions, with multiple individuals found dead after being hooked by fishers. [ABSTRACT FROM AUTHOR]

Dolphins live in complex social systems with a wide variety of grouping and association patterns. Understanding the spatiotemporal variation of these associations (fission–fusion dynamics) is necessary to investigate the underlying factors and mechanisms shaping mammalian social systems in aquatic environments. We used boat-based surveys, photoidentification, focal observations, association analyses and social network techniques to quantify variation in the grouping patterns and fission–fusion dynamics of small, sympatric populations of Australian snubfin dolphins, Orcaella heinsohni, and Indo-Pacific humpback dolphins, Sousa chinensis, off the northeast coast of Queensland. Schools of snubfin dolphins were larger and more stable, irrespective of behavioural activity, than those of humpback dolphins. While associations of both species showed nonrandom patterns and structure, the social network of snubfin dolphins was characterized by numerous strong associations, whereas the strength of the humpback dolphin’s social network did not differ from random. Modelling of temporal patterns of association indicated long-lasting associations were an important feature of snubfin dolphins’ fission–fusion dynamics. In contrast, associations among humpback dolphins over time were best described by short-term relationships. The contrasting grouping and fission–fusion dynamics of snubfin and humpback dolphins appear to be a response to different feeding habits and prey availability. Future studies involving molecular techniques and direct quantification of food availability and predation risk will help elucidate the suite of interacting ecological, social and evolutionary factors shaping their social structures. [ABSTRACT FROM AUTHOR]

The abundance of New Zealand subantarctic southern right whales ( Eubalaena australis) was estimated for the first time using mark-recapture methods based on photo-identification and microsatellite genotyping (13 loci). Individual identification photographs of 383 whales and microsatellite genotypes of 235 whales were collected during annual austral winter field surveys from 1995 to 1998. Given the 4-year survey period and lack of geographic and demographic closure, we estimated super-population abundance using the POPAN Jolly-Seber model implemented in the software programme MARK. Models with constant survivorship but time-varying capture probability and probability of entry into the population were the most suitable due to the survey design. This provided estimates of abundance in 1998 of 908 non-calf whales (95% C.L. = 755, 1,123) for the photo-identification and 910 non-calf whales (95% C.L. = 641, 1,354) for the microsatellite genotype data sets. The current estimate of 900 whales may represent less than 5% of the pre-whaling abundance in New Zealand waters. [ABSTRACT FROM AUTHOR]

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.

We estimated the abundance of humpback whales in the North Pacific by capture-recapture methods using over 18,000 fluke identification photographs collected in 2004-2006. Our best estimate of abundance was 21,808 (CV = 0.04). We estimated the biases in this value using a simulation model. Births and deaths, which violate the assumption of a closed population, resulted in a bias of +5.2%, exclusion of calves in samples resulted in a bias of −10.5%, failure to achieve random geographic sampling resulted in a bias of −0.4%, and missed matches resulted in a bias of +9.3%. Known sex-biased sampling favoring males in breeding areas did not add significant bias if both sexes are proportionately sampled in the feeding areas. Our best estimate of abundance was 21,063 after accounting for a net bias of +3.5%. This estimate is likely to be lower than the true abundance due to two additional sources of bias: individual heterogeneity in the probability of being sampled (unquantified) and the likely existence of an unknown and unsampled breeding area (−8.7%). Results confirm that the overall humpback whale population in the North Pacific has continued to increase and is now greater than some prior estimates of prewhaling abundance. [ABSTRACT FROM AUTHOR]

The article focuses on the presence of two satellite-tagged pygmy killer whales or Feresa attenuata in the Hawaiian Islands. It states that a single stock of pygmy killer whales has been recognized in the Exclusive Economic Zone (EEZ) surrounding the island. It mentions that a long-term photographic-identification study has determined a small population with high site of fidelity around the island. It adds that the two dorsal fins indicate movements and habitat use in the island.

The article presents a study which presents population estimates of Irrawaddy dolphins, Orcaella brevirostris, in Chilika Lagoon, India obtained from photo-identification based mark-recapture methods. The study used a Canon digital camera and open and closed population models to estimate the population of Irrawaddy dolphins in the region. Results show that mark-recapture methodology has provided significant information on Irrawaddy dolphins.

For amphibians with complex life cycles, the regulation of populations may occur in each life history stage and although available data stress the importance of studying amphibian population dynamics during the larval stage, most studies so far still focus only on the adult phase, due to the difficulty to estimate larval survival under field conditions. Through a two-months capture-recapture study of 646 photo-identified tadpoles of Alytes cisternasii we aimed to estimate tadpole survival in isolated temporary stream pools - their main habitat - as well as to evaluate how pool characteristics and intraspecific competition (tadpole density) affect this parameter. Photo-identification was performed with the help of the software I3S. We used the POPAN formulation of the Jolly-Seber model to estimate survival rates and population size in 9 stream pools. Tadpole density varied from ∼1 to 40 tadpoles · m-2. Tadpole weekly survival was relatively high, varying from 75 to 99% · week-1. Among-pool differences in survival were best explained by pool depth, and not by tadpole density or other pool characteristics. The lower survival estimates were obtained for the deep pools. The very high survival estimates for some pools are an indication that this type of discrete habitat may play an important role for this species. To our knowledge, this is the first time that photo-identification is used to obtain estimates for survival and density of tadpoles. [ABSTRACT FROM AUTHOR]

The article focuses on the study of the Russia-U.S. research project regarding the identification of western gray whale calves on their primary feeding grounds in Okhotsk Sea. It states that methods applied such as barnacle appearance, age, and scarring observations on whale calves using photo-identification. Results revealed that recently attached barnacles from gray whale calves vary in appearance and some calves are not afflicted with scarring on their head and postcranial region.

In mark-recapture studies, various techniques can be used to uniquely identify individual animals, such as ringing, tagging or photo-identification using natural markings. In some long-term studies more than one type of marking procedure may be implemented during the study period. In these circumstances, ignoring the different mark types can produce biased survival estimates since the assumption that the different mark types are equally catchable (homogeneous capture probability across mark types) may be incorrect. We implement an integrated approach where we simultaneously analyse data obtained using three different marking techniques, assuming that animals can be cross-classified across the different mark types. We discriminate between competing models using the AIC statistic. This technique also allows us to estimate both relative mark-loss probabilities and relative recapture efficiency rates for the different marking methods. We initially perform a simulation study to explore the different biases that can be introduced if we assume a homogeneous recapture probability over mark type, before applying the method to a real dataset. We make use of data obtained from an intensive long-term observational study of UK female grey seals ( Halichoerus grypus) at a single breeding colony, where three different methods are used to identify individuals within a single study: branding, tagging and photo-identification based on seal coat pattern or pelage. [ABSTRACT FROM AUTHOR]

The size and structure of a photographically identified population of reef manta ray, Manta alfredi, were examined at aggregation sites over a four-year period in southern Mozambique. The use and standardisation of photo-ID techniques was examined as a minimally-intrusive means to study this species. Using these techniques, we report on the size, structure and seasonality of this population of M. alfredi. In total, 449 individuals were identified during this time period, 40.5% of which were re-sighted on at least one occasion. The longest period between re-sighting events was 1,252 days. During the study period, annual population size estimates for M. alfredi ranged from 149 to 454 individuals. The superpopulation size estimate for the entire study period was 802 individuals, the first reported for M. alfredi at a monitored aggregation site. A highly significant sex bias was evident with a female:male ratio of 3.55:1. The majority of rays (89.9% males; 49.7% females) were considered mature, with most individuals between 3.0 and 4.9 m in disc width. Manta alfredi were observed at the study sites in each month of the calendar year. The maximum number of individual rays seen per dive was 30. Large numbers of rays (20 + per dive) were seen in the months of November, December and January, which coincide with the breeding season. Natural markings were unique to individuals and did not change substantially with time, which provided further support for their use in the identification of individual M. alfredi over multiple years. Multiple re-sightings of individual M. alfredi suggest that many individuals in this population exhibit site fidelity to the examined aggregation sites. As target subsistence fishing for M. alfredi exists along the Mozambican coastline, management efforts to monitor and prevent overexploitation at these critical habitats should be a priority. [ABSTRACT FROM AUTHOR]

Abstract: We provide estimates of population size and other demographic variables for individually-identified Asian elephants (Elephas maximus) in Uda Walawe National Park (UWNP), Sri Lanka based on systematic year-round observations. Two hundred and eighty-six adult females and 241 adult males were identified, of which four adults (2% of males) had tusks. Sightings-based demographic models showed seasonal immigration and emigration from the study area. The total population, including non-adults, was between 804 and 1160 individuals. Density ranged from 102 to 116 adult females per 100 km2 and remains at this level throughout the year. This large, un-fragmented population of Asian elephants should be of high conservation priority. We find that estimates of survivorship and migration rates should be based on long sampling intervals when possible, but estimates of density and population size can still be made when observations are constrained to shorter intervals, if spatial data are available. We offer suggestions to guide census design for other elephant populations or cryptic species. We urge that other locations be systematically surveyed as well using photographic identification. [Copyright &y& Elsevier]

Abstract: Bottlenose dolphins (Tursiops truncatus) are apex predators in coastal southeastern U.S. waters; as such they are indicators of persistent organic pollutants (POPs) in coastal ecosystems. POP concentrations measured in a dolphin''s blubber are influenced by a number of factors, including the animal''s sex and ranging pattern in relation to POP point sources. This study examined POP concentrations measured in bottlenose dolphin blubber samples (n=102) from the Georgia, USA coast in relation to individual ranging patterns and specifically, distance of sightings from a polychlorinated biphenyl (PCB) point source near Brunswick, Georgia. Dolphin ranging patterns were determined based upon 5years of photo-identification data from two field sites approximately 40km apart: (1) the Brunswick field site, which included the Turtle/Brunswick River Estuary (TBRE), and (2) the Sapelo field site, which included the Sapelo Island National Estuarine Research Reserve (SINERR). Dolphins were categorized into one of three ranging patterns from photo-identification data. Individuals with sighting histories exclusively within one of the defined field sites were considered to have either Brunswick or Sapelo ranging patterns. Individuals sighted in both field sites were classified as having a Mixed ranging pattern. Brunswick males had the highest concentrations of PCBs reported for any marine mammal. The pattern of PCB congeners was consistent with Aroclor 1268, a highly chlorinated PCB mixture associated with a Superfund site in Brunswick. PCB levels in Sapelo males were lower than in Brunswick males, but comparable to the highest levels measured in other dolphin populations along the southeastern U.S. Female dolphins had higher Aroclor 1268 proportions than males, suggesting that the highly chlorinated congeners associated with Aroclor 1268 may not be offloaded through parturition and lactation, as easily as less halogenated POPs. Individuals sighted farther from the Superfund point source had lower Aroclor 1268 proportions. [Copyright &y& Elsevier]

Abstract: The sperm whale is one of the very few deep diving mammal species in the Mediterranean Sea. Following a rare mass stranding of male sperm whales in the Adriatic Sea in December 2009, photo-identification methods were used in order to investigate previous sightings of the stranded whales in the region. Fluke photos of the stranded whales were compared with those of 153 and 128 free-ranging individuals photographed in the western and eastern Mediterranean basins, respectively. Three out of the seven stranded whales had been previously photo-identified and some of them more than once. To reach the stranding place, two of these re-identified whales performed long-range inter-basin movements of about 1600–2100km (in a straight line) either through the Strait of Sicily or the Strait of Messina. In addition, comparisons among all whales photographed in the two Mediterranean basins revealed that one more individual first photographed in the western basin (1991) was re-identified 13 years later in the eastern basin (2004). These three cases provide the first conclusive evidence of inter-basin movement of sperm whales in the Mediterranean Sea. Inter-basin gene flow is important for the survival of the small and endangered Mediterranean sperm whale population. Mitigating the disturbance created by human activities in the straits area is crucial for its conservation. [Copyright &y& Elsevier]

Spectrophotometers allow the objective measurement of colour and as a result are rapidly becoming a key piece of equipment in the study of animal colouration; however, they also have some major limitations. For example, they can only record point samples, making it difficult to reconstruct topographical information, and they generally require subjects to be inanimate during measurement. Recently, the use of digital cameras has been explored as an alternative to spectrophotometry. In particular, this allows whole scenes to be captured and objectively converted to animal colour space, providing spatial (and potentially temporal) data that would be unobtainable using spectrophotometry; however, mapping between camera and animal colour spaces requires knowledge of the spectral sensitivity functions of the camera's sensors. This information is rarely available, and making direct measures of sensor sensitivity can be prohibitively expensive, technically demanding and time-consuming. As a result, various methods have been developed in the engineering and computing sciences that allow sensor sensitivity functions to be estimated using only readily collected data on the camera's response to a limited number of colour patches of known surface reflectance. Here, I describe the practical application of one such method and demonstrate how it allows the recovery of sensor sensitivities (including in the ultraviolet) with a high enough degree of accuracy to reconstruct whole images in terms of the quantal catches of an animal's photoreceptors, with calculated values that closely match those determined from spectrophotometric measurements. I discuss the potential for this method to advance our understanding of animal colouration. [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]

Species that have temperature-dependent sex determination (TSD) often produce highly skewed offspring sex ratios contrary to long-standing theoretical predictions. This ecological enigma has provoked concern that climate change may induce the production of single-sex generations and hence lead to population extirpation. All species of sea turtles exhibit TSD, many are already endangered, and most already produce sex ratios skewed to the sex produced at warmer temperatures (females). We tracked male loggerhead turtles (Caretta caretta ) from Zakynthos, Greece, throughout the entire interval between successive breeding seasons and identified individuals on their breeding grounds, using photoidentification, to determine breeding periodicity and operational sex ratios. Males returned to breed at least twice as frequently as females. We estimated that the hatchling sex ratio of 70:30 female to male for this rookery will translate into an overall operational sex ratio (OSR) (i.e., ratio of total number of males vs females breeding each year) of close to 50:50 female to male. We followed three male turtles for between 10 and 12 months during which time they all traveled back to the breeding grounds. Flipper tagging revealed the proportion of females returning to nest after intervals of 1, 2, 3, and 4 years were 0.21, 0.38, 0.29, and 0.12, respectively (mean interval 2.3 years). A further nine male turtles were tracked for short periods to determine their departure date from the breeding grounds. These departure dates were combined with a photoidentification data set of 165 individuals identified on in-water transect surveys at the start of the breeding season to develop a statistical model of the population dynamics. This model produced a maximum likelihood estimate that males visit the breeding site 2.6 times more often than females (95%CI 2.1, 3.1), which was consistent with the data from satellite tracking and flipper tagging. Increased frequency of male breeding will help ameliorate female-biased hatchling sex ratios. Combined with the ability of males to fertilize the eggs of many females and for females to store sperm to fertilize many clutches, our results imply that effects of climate change on the viability of sea turtle populations are likely to be less acute than previously suspected. [ABSTRACT FROM AUTHOR]

The Shannon Estuary is home to Ireland's only known resident population of bottlenose dolphins (Tursiops truncatus) and is designated as a candidate Special Area of Conservation (cSAC) for this species. Proper conservation management of these dolphins requires an understanding of the social structure of this population. Four years of photoidentification data (2005 to 2009, excluding 2007) were used to construct sociograms that complement a cluster analysis of individually marked dolphins and their associates. The results found little evidence of social stability or group fidelity for this study's dolphin population. Analysis of dolphins observed in consecutive years showed that the probability of group members encountering an individual dolphin in the second year did not depart from a random model. The social parameters for this resident population seem to be typical for this species. Bottlenose dolphins are found to exhibit a highly fluid, dynamic social structure within which individuals change their composition and associates regularly. These dolphins in the Shannon Estuary appear to live in a fission-fusion based society. [ABSTRACT FROM AUTHOR]

Social assortativity, where individuals preferentially mix with certain conspecifics, is widespread among a diverse range of taxa. Animals may assort by a variety of characteristics and receive substantial benefits from these interactions, such as a reduction in predation risk, increased foraging efficiency or greater access to resources. We investigated the social network structure of an embayment population of Indo-Pacific bottlenose dolphins, Tursiops aduncus, using a long-term photoidentification data set, and examined the impact of sex and kinship in maintaining the cohesion of the social network. We applied recently developed social network techniques that incorporate uncertainty into statistical measures to delineate four smaller social groups within two previously defined communities. Temporal stability of associations within social groups was substantially greater than among individuals from different groups. We also found that the dolphin population was not strongly segregated by sex and both males and females had similar degrees of social connectivity in the network. Moreover, genetic analyses showed that relatedness had a greater influence on female than on male social relationships, as association strength was positively correlated with genetic relatedness between females and between female and male pairs, but not between males. These results suggest that females and males may target kin interactions with females and that kinship appears to be important for maintaining the cohesiveness of this dolphin social network. [ABSTRACT FROM AUTHOR]

The article compares the land-based and floating calibration targets that are used to measure whale lengths through aerial photogrammetry. It says that most studies on aerial photogrammetry of marine mammals have used land-based calibration targets to scale photographic measurement to actual measurement. The result shows that there was no difference in the obtained measurements between land-based and floating calibration targets.

During the 1990s, North Atlantic right whales had significantly decreased reproduction and showed signs of compromised health, prompting the initiation of noninvasive fecal-based studies to investigate potential causal factors. The interpretation of these studies is enhanced when the defecator is identified, as data can then be linked to individual life history information. Fecal samples ( n= 118) were either collected from single photoidentified whales, associated with several individuals by photoidentification of whales in the vicinity upon sample collection, or were collected when no whales were in the vicinity. Genetic profiles from fecal DNA comprising sex, mitochondrial haplotype, and five microsatellite loci helped assign specific samples to individual right whales based on existing genetic profiles. Profiles were informative in assigning 61 fecal samples to known individuals, 24 of which were collected when no whales were in the vicinity. Whales identified genetically were typically photographed in the same habitat area and on the same day of sample collection ( n= 35/48). Twelve profiles new to the genetic database were identified, suggesting fecal sampling provides a means to obtain genetic profiles from previously unsampled individuals, which may help refine estimates of population size and habitat use patterns if annual fecal sampling continues. [ABSTRACT FROM AUTHOR]

Site fidelity and movements were studied for humpback whales photo-identified from 1989 to 2006 in the Abrolhos Bank, southwestern Atlantic, Brazil. A total of 2,612 individuals were identified, 374 of which were observed on more than one occasion. The cumulative number of identified whales has increased since 1989. Recapture rate was low and varied among different years. A total of 33 whales was observed using the Abrolhos Bank for longer than 10 yr, up to a maximum of 16 yr. Our data suggest that different whales show distinct movement rates. Some whales used a large extent of the Abrolhos Bank region. Opportunistic photo-identification data (on the scale of the Brazilian coast from 4° to 23°S) revealed important information about stock identity. The longest distance between within-season resightings was over 600 km, while one whale was observed in two locations separated by more than 1,400 km in different years. Long-range movements within and between seasons support the single stock hypothesis for humpback whales wintering off the Brazilian coast. [ABSTRACT FROM AUTHOR]

In this study we present empirical data on predator numbers, movements and area usage, and predation obtained from tracking transient killer whales Orcinus orca throughout the inland waters of southeastern Alaska, USA. During 1991- 2007, we documented 155 transient killer whales via photo-identification methodology within the large study area (27,808 km2). Transient killer whales were distributed throughout southeastern Alaska and were present during all seasons, although not all individuals were seen every year. Resighting data suggested that within southeastern Alaska, maternal groups may partition area usage of their environment. By following whales for 1,467 km, we calculated a mean travel speed of 7.2 km/hour with mean daily movements of 134 km688 km/24 hours and ranging within 59-240 km/24 hours. Photographic matches demonstrated that most of the transient killer whales (86%) identified in southeastern Alaska also utilized British Columbia and Washington State waters. In contrast, photographic matches between whales in southeastern Alaska and whales seen off of California, USA, were rare, suggesting that different transient killer whale stocks occupy these two regions. Transient killer whales preyed upon Dall’s porpoise Phocoenoides dalli, Pacific whitesided dolphins Lagenoryhncus obliquidens, harbor porpoise Phocoena phocoena, minke whales Balaenoptera acutorostrata, Steller sea lions Eumetopias jubatus, harbor seals Phoca vitulina and seabirds. Potential prey species that were available, but not targeted, included humpback whales Megaptera novaeangliae, elephant seals Mirounga angustirostris and sea otters Enhydra lutris. Prey-handling techniques varied depending on the prey being targeted with no evidence of prey specialization. During 114 encounters totaling 332.5 hours of direct observations of transient killer whales, we documented 36 predation events for a calculated kill rate of 0.62 prey items/24-hour period/whale. The data we present in this article provide a foundation of transient killer whale ecology aimed at improving our ability to understand the impact of transient killer whale predation on southeastern Alaska prey populations. [ABSTRACT FROM AUTHOR]

The article discusses a research study on Bering Chukchi-Beaufort (B-C-B) bowhead whale abundance in Alaska using photo-identification data in 2004. Concerns were raised on the inaccuracy of ice-based survey that aerial photographic surveys were done in Alaska during bowhead whales spring migrations from 2003 to 2005, where marked whales data were gathered through a closed population model for capture-recapture. Investigated were other models accounting for heterogeneity but the simple, no covariates model was used resulting to an estimate of 12,631 B-C-B bowhead abundance with a 95% bootstrap percentile confidence interval and 5% lower limit. Conclusions indicated the consistency of photographic data with the trend estimates and expectations of the ice-based surveys from 1978-2001.

The article presents a study regarding the development of a computer-aided matching system for humpback whale flukes in Australia. It states that the Fluke Matcher system provides a user-friendly graphical interface wherein new fluke photographs can be added into the database which is written in FORTRAN on a Windows-based personal computer. It mentions that the study is funded by the Department of Environment and Heritage.

The narwhal is a hunted species for which we have many knowledge gaps. Photo-identification, which uses photographs of natural markings to identify individuals, is widely used in cetacean studies and can address a broad range of biological questions. However, it has not been developed for narwhals. The marks used for other cetaceans are inappropriate for this species either because narwhals lack the body part on which these marks are found or because the marks are known to change with time. We investigated the marks apparent in photographs of narwhals. Nicks and notches on the dorsal ridge are the mark types most promising for photo-identification. They are found on 91%–98% of the individuals, thus allowing the identification of a large part of the population. They can be used to differentiate between individuals, in part because they are variable in their location, numbers, shape, and size. Although our results suggest that nicks and notches are relatively stable over time, rates of change should be formally measured to assess the probability of photographic matches over multiple years. However, we are confident that these marks can be used in studies spanning at least a field season. [ABSTRACT FROM AUTHOR]

The article presents a study which investigated the size of a closed population of bowhead whales in the Bering-Chukchi-Beaufort seas using photo-identification data and Empirical Bayes capture-recapture analysis. The authors estimated the capture probabilities and the abundance of the mammals for populations including unmarked individuals. It is stated that Empirical Bayes approach resulted in smaller or comparable biases for the estimated values of the population compared to the biases observed using the beta prior.

Copyright of Revista Brasileira de Biociencias is the property of Revista Brasileira de Biociencias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Knowledge of the local and migratory movements of humpback whales (Megaptera novaeangliae) from New Caledonia is very limited. To investigate this topic, we attached satellite-monitored tags to 12 whales off southern New Caledonia. Tag longevity ranged from 1 to 52 days (&#x00AI; = 22.5 days). Tagged whales generally moved to the south or southeast, with several spending time in a previously unknown seamount habitat named Antigonia before resuming movement, generally toward Norfolk Island or New Zealand. However, 1 female with a calf traveled the entire length of the western coast of New Caledonia (~450 km) and then west in the direction of the Chesterfield Reefs, a 19th century American ("Yankee") whaling ground. None of the New Caledonia whales traveled to or toward eastern Australia, which is broadly consistent with the low rate of interchange observed from photo-identification comparisons between these 2 areas. The connections between New Caledonia and New Zealand, together with the relatively low numbers of whales seen in these places generally, support the idea that whales from these 2 areas constitute a single population that remains small and unrecovered. [ABSTRACT FROM AUTHOR]

Bottlenose dolphins (Tursiops truncatus) are consistently observed in the Marlborough Sounds, New Zealand. However, prior to the present study, no research has previously focused on this species within these waters, despite the potential for human impacts. Photo-identification undertaken during boat-based surveys conducted between 2003 and 2005 were used to assess occurrence, abundance, and movement patterns of bottlenose dolphins in the Marlborough Sounds. Longterm site fidelity was evident, with the majority of individuals resighted over multiple years. Lagged identification rates showed consistency over a 4-y period, with some individuals remaining for longer periods, while others frequently interchanged between different areas of the Marlborough Sounds. Migration rates were high, with approximately 25% leaving and entering the 890 km² region annually. Bottlenose dolphins in the Marlborough Sounds appear to form part of a larger, open, coastal population consisting of 385 individuals, with 211 (95% CI = 195 to 232) dolphins utilizing the region per annum. While their occurrence within these waters is frequent, the Marlborough Sounds appear to be only a section of a much larger home range for this bottlenose dolphin population. [ABSTRACT FROM AUTHOR]

During the winter/spring months from 1990 to 2009, 13 cetacean surveys were conducted around the Cape Verde Islands off West Africa. The main target species was the humpback whale (Megaptera novaeangliae). Study periods varied from 14 to 90 d in duration. Study platforms included a 5-m inflatable boat, a 12-m catamaran, and/or 15-m sailing or motor vessels. Collectively, we obtained 88 individual humpback fluke photographs from this region. These fluke photographs have been compared to over 6,500 individual fluke photographs maintained in the North Atlantic Humpback Whale Catalogue. Based on photoidentification, humpbacks in the Cape Verde Islands have a relatively high interannual resight rate (> 22%) compared to other studied breeding locations in the West Indies. While this is partly due to increased probability of detection in a small population, this result nonetheless suggests strong site fidelity to this breeding ground. Three photo-identified individuals from the Cape Verde Islands had been previously photographed on high-latitude feeding grounds off Bear Island, Norway, and Iceland. One Cape Verdean humpback was resighted in the Azores, possibly en route to the northern feeding grounds. These findings are consistent with the belief that the Cape Verde Islands represent a breeding ground for northeastern Atlantic humpback whales. Tourism activities in the Cape Verde Islands are rapidly increasing. A balance is needed whereby conservation, whale watching guidelines, habitat preservation, and enforcement are fully enacted in order to provide protection to both this species and its habitat. In addition, further research is required to clarify the importance of this small population and its breeding ground. [ABSTRACT FROM AUTHOR]