Endangered Species Research

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ISSN / EISSN : 1863-5407 / 1613-4796
Published by: Inter-Research Science Center (10.3354)
Total articles ≅ 1,202
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Em Thomas, Kai Nekaris, Ma Imron, P Cassey, Cr Shepherd, V Nijman
Endangered Species Research, Volume 46, pp 67-78; https://doi.org/10.3354/esr01142

Abstract:
Wildlife trade is increasingly impeding the conservation of imperilled wildlife and is a potential threat to human health. Ferret badgers are extensively traded in China, although the trends, drivers and health implications of ferret badger trade in other parts of Asia remain poorly known. Here, we focus on the pet trade of a little known endemic small carnivore species, Javan ferret badger Melogale orientalis in Indonesia, over a 10 yr period (2011-2020). The Javan ferret badger is listed as Least Concern on the IUCN Red List of Threatened Species with an unknown population trend. We aimed to gain insight into the magnitude of this trade, its purposes, price trends, distribution records, health risks and shifts to online platforms. We documented 44 ferret badgers in 11 wildlife markets in Java and Bali and 100 ferret badgers for sale on online platforms. We observed a shift in trade from traditional animal markets only, to trade in these markets as well as online. Asking prices, corrected for inflation, declined significantly from ~USD 37 in 2012 to ~USD 22 in 2020, and were related to the purchasing power in cities where trade occurred. Widespread sale of the species highlights that enforcement continues to be overly passive as any trade in the species is illegal. We recommend that the Javan ferret badger be afforded full national protection and prioritised in monitoring efforts to establish its true conservation status. Additionally, concerted efforts are needed to determine if online trade poses a risk to conservation and human health.
, Pe Michael, Js Gleason, Jc Haney, Yg Satgé
Endangered Species Research, Volume 46, pp 49-65; https://doi.org/10.3354/esr01143

Abstract:
The black-capped petrel Pterodroma hasitata is an Endangered seabird endemic to the western North Atlantic. Although estimated at ~1000 breeding pairs, only ~100 nests have been located at 2 sites in Haiti and 3 sites in the Dominican Republic. At sea, the species primarily occupies waters of the western Gulf Stream in the Atlantic and the Caribbean Sea. Due to limited data, there is currently no consensus on the geographic marine range of the species although no current proposed ranges include the Gulf of Mexico. Here, we report on observations of black-capped petrels during 2 vessel-based survey efforts throughout the northern Gulf of Mexico from 2010-2011 and 2017-2019. During 558 d and ~54700 km of surveys, we tallied 40 black-capped petrels. Most observations occurred in the eastern Gulf, although birds were observed over much of the east-west and north-south footprint of the survey area. Predictive models indicated that habitat suitability for black-capped petrels was highest in areas associated with dynamic waters of the Loop Current. We used the extent of occurrence and area of occupancy concepts to delimit the geographic range of the species within the northern Gulf. We suggest that the marine range for black-capped petrels be modified to include the northern Gulf of Mexico, recognizing that distribution may be more clumped in the eastern Gulf and that occurrence in the southern Gulf remains unknown due to a lack of surveys there. To date, however, it remains unclear which nesting areas are linked to the Gulf of Mexico.
, Se Parks, Dp Nowacek
Endangered Species Research, Volume 46, pp 35-48; https://doi.org/10.3354/esr01141

Abstract:
The North Atlantic right whale Eubalaena glacialis is a Critically Endangered whale whose habitat overlaps with areas of high human use. On feeding grounds, aspects of its behavior increase the vulnerability of this species to anthropogenic threats such as entanglement in fishing gear and vessel strikes. On the calving ground, natural dive behavior and the implications for conservation efforts in this species remain to be evaluated. In this study, we used 102.17 h of tag data collected over 15 deployments of archival tags on 14 individuals to describe the dive behavior of right whales in the Southeast USA. Lactating females spent up to 80% of the time at depths ≤3.5 m, leading to increased risk of vessel strike compared to other whale groups that spent a maximum of 30% of the time at those depths in this habitat. Non-lactating whales had significantly deeper maximum dive depths (12.1 m) than lactating females (7.3 m) and spent more time in the bottom phase of dives, closer to the sea floor (45 vs. 37% of the dive duration, respectively). Time spent closer to the sea floor increases the probability of interaction with fishing gear. Therefore, these dive data are useful to justify seasonal closures of fishing activity on the calving ground to protect both lactating and non-lactating whales. Opportunistic comparisons revealed that diel period, calf presence and calf age affect dive behavior of female right whales. In the face of the impacts of anthropogenic mortality on right whale populations, these results will aid vessel strike and entanglement risk assessment on the Southeast USA calving ground.
L González-Cortés, E Labastida-Estrada, Sg Karam-Martínez, Ja Montoya-Márquez,
Endangered Species Research, Volume 46, pp 79-90; https://doi.org/10.3354/esr01144

Abstract:
Multiple paternity is common to all sea turtle species, but its causes and consequences are hard to ascertain and the behaviors and success of males difficult to observe. This study aims to describe patterns of multiple paternity for olive ridley turtles Lepidochelys olivacea at Playa de Escobilla, an ‘arribada’ (mass-nesting) site on the Mexican Pacific coast with over a million clutches laid each reproductive season. A total of 15 females and their hatchlings were sampled during 3 arribada events which occurred over the 2016-2017 nesting season. Females and hatchlings (N = 329) were genotyped at 5 microsatellite loci, from which we inferred the alleles of 46 contributing males. Multiple paternity was detected in 60% of the analyzed clutches, which were sired by a range of 2 to 7 males. Multiple paternity rates differed significantly across arribada events, suggesting more males achieved fertilizations earlier in the breeding season. Paternal contribution in 6 of the clutches with multiple paternity was skewed towards a single male; the remaining clutches had a homogeneous male contribution. However, our results are based on relatively small within-arribada sample sizes. The frequency of multiple paternity among turtle clutches laid on this arribada beach could be related to the density of breeding individuals in the reproductive patch off Playa de Escobilla, rather than to the nesting population size or female size.
Jm Lindsay, Kl Laidre, Pb Conn, Ee Moreland, Pl Boveng
Endangered Species Research, Volume 46, pp 1-17; https://doi.org/10.3354/esr01140

Abstract:
Ringed seals Pusa hispida are reliant on snow and sea ice for denning, and a better understanding of ringed seal habitat selection and timing of emergence from snow dens (also called lairs) is needed to quantify and predict effects of climate change in the Arctic. We used generalized additive models to assess relationships between ringed seal counts, from spring aerial surveys in the Bering Sea (2012 and 2013) and Chukchi Sea (2016), and spatiotemporal covariates including survey date, remotely sensed snow and sea-ice values, and short-term weather data. We produced separate models for total ringed seal counts and for pup counts within each region. Our models showed that in both areas, total ringed seal counts increased over the course of the spring, especially after 15 May, indicating emergence from lairs and/or the onset of basking behavior. For the more northerly Chukchi Sea, we found a substantial unimodal effect of snow melt progression and a positive effect of snow depth on total ringed seal counts. In contrast, Bering Sea total ringed seal counts and pup counts in both regions were affected much more strongly by date than by habitat variables. Overall, our findings demonstrate that snow depth and melt play an important role in the timing of ringed seal den emergence, particularly in the Chukchi Sea, and suggest that ringed seal denning may be affected by continued shifts in melt and snow depth associated with climate change.
, J Have Rasmussen, B Sterba-Boatwright, A Širović
Endangered Species Research, Volume 46, pp 19-33; https://doi.org/10.3354/esr01145

Abstract:
The Northeast Pacific (NEP) population of blue whales Balaenoptera musculus musculus is currently managed as a single stock. We investigated the fine-scale frequency characteristics of 1 NEP blue whale song unit, the B call. We analyzed B calls from passive acoustic data collected between 2010 and 2013 at 2 low-latitude sites, Palmyra Atoll and the Hawaiian Islands, and 3 higher-latitude sites, off southern California, off Washington state and in the Gulf of Alaska. Frequency measurements were extracted along the contour of the third harmonic from each call, and data from each region were compared. Calls from the Gulf of Alaska and Hawai‘i presented a downshift in frequency, beginning just past the midway point of the contour, which was not present in calls recorded from southern California or Palmyra Atoll. Calls from Washington displayed intermediate characteristics between those from the other 2 high-latitude sites. Cluster analysis resulted in consistent grouping of call contours from Washington and southern California, in what we termed the NEP B1 variant, while contours from Hawai‘i and the Gulf of Alaska were grouped together, as a NEP B2 variant. Frequency differences were also observed among the variants; the Gulf of Alaska displayed the highest frequency on average, followed by Washington, then southern California. Consistent with other studies, a yearly decline in the frequency of B calls was also observed. This discovery of at least 2 geographically distinct variants provides the first evidence of vocally distinct subpopulations within the NEP, indicating the possibility of a need for finer-scale population segmentation.
, F Trujillo, M Oliveira-Da-Costa, M Marmontel, Pa Van Damme, N Franco, L Córdova, E Campbell, J Alfaro-Shigueto, Jl Mena, et al.
Endangered Species Research, Volume 45, pp 269-282; https://doi.org/10.3354/esr01133

Abstract:
Studying the variables that describe the spatial ecology of threatened species allows us to identify and prioritize areas that are critical for species conservation. To estimate the home range and core area of the Endangered (EN) Amazon river dolphin Inia geoffrensis, 23 individuals (6♀, 17♂) were tagged during the rising water period in the Amazon and Orinoco river basins between 2017 and 2018. The satellite tracking period ranged from 24 to 336 d (mean ± SE = 107 ± 15.7 d), and river dolphin movements ranged from 7.5 to 298 km (58 ± 13.4 km). Kernel density estimates were used to determine minimum home ranges at 95% (K95 = 6.2 to 233.9 km2; mean = 59 ± 13.5 km2) and core areas at 50% (K50 = 0.6 to 54.9 km2; mean = 9 ± 2.6 km2). Protected areas accounted for 45% of the K50 estimated core area. We observed dolphin individuals crossing country borders between Colombia and Peru in the Amazon basin, and between Colombia and Venezuela in the Orinoco basin. Satellite tracking allowed us to determine the different uses of riverine habitat types: main rivers (channels and bays, 52% of recorded locations), confluences (32%), lagoons (9.6%), and tributaries (6.2%). Satellite monitoring allowed us to better understand the ecological preferences of the species and demonstrated the importance of maintaining aquatic landscape heterogeneity and spatial connectivity for effective river dolphin conservation.
, S Leiter, Tvn Cole, Mn Hagbloom, Ar Knowlton, P Nagelkirk, O O’Brien, Cb Khan, Ag Henry, Pa Duley, et al.
Endangered Species Research, Volume 45, pp 251-268; https://doi.org/10.3354/esr01137

Abstract:
Offshore wind energy development is growing quickly around the world. In southern New England, USA, one of the largest commercial offshore wind energy farms in the USA will be established in the waters off Massachusetts and Rhode Island, an area used by the Critically Endangered North Atlantic right whale Eubalaena glacialis. Prior to 2011, little was known about the use of this area by right whales. We examined aerial survey data collected between 2011-2015 and 2017-2019 to quantify right whale distribution, residency, demography, and movements in the region. Right whale occurrence increased during the study period. Since 2017, whales have been sighted in the area nearly every month, with peak sighting rates between late winter and spring. Model outputs suggest that 23% of the species’ population is present from December through May, and the mean residence time has tripled to an average of 13 d during these months. Age and sex ratios of the individuals present in the area are similar to those of the species as a whole, with adult males the most common demographic group. Movement models showed that southern New England is an important destination for right whales, including conceptive and reproductive females, and qualitative observations included animals feeding and socializing. Implementing mitigation procedures in coordination with these findings will be crucial in lessening the potential impacts on right whales from construction noise, increased vessel traffic, and habitat disruption in this region.
, R Barreto, Fm Santana, Rpt Lessa
Endangered Species Research, Volume 45, pp 237-249; https://doi.org/10.3354/esr01131

Abstract:
The silky shark Carcharhinus falciformis is considered one of the least productive pelagic shark species. The estimation of growth and demographic parameters presented here is fundamental to a sound knowledge of population status of the species in the Atlantic Ocean. Data was collected through an onboard observer program of the Brazilian chartered pelagic longline fishing fleet that operates in the Equatorial Southwestern Atlantic. Vertebral analysis produced the von Bertalanffy growth parameters for pooled sexes L ∞ = 283.05 cm; k = 0.0987 yr-1 and t 0 = -3.47 yr. Males reached sexual maturity at 8.6 yr and females at 9.9 yr. Longevity was estimated at 27.2 yr. Age structure analysis indicated that 80.5% of the catch was composed of juveniles, with recruitment to the fishery from the first year of life (age 1+). These biological parameters are responsible for the species’ low resistance to fishing pressure, and our demographic analysis (Leslie Matrix) shows an annual population decline of 12.7% yr-1 under the current fishing scenario for the period analyzed. Therefore, conservation measures must be enacted to reestablish the population of silky sharks to safe levels for the maintenance of this species in the South Atlantic.
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