Olive Ridley Lepidochelys Olivacea Research Articles

Nowhere to hide: Sea turtle bycatch in Northwest Africa

Abstract Fisheries bycatch is considered the largest threat to sea turtle populations globally. However, it has been challenging to assess the impact of bycatch on sea turtles in some regions such as Northwest Africa (i.e. Cabo Verde, Guinea, Guinea–Bissau, Mauritania, Senegal, Sierra Leone and The Gambia) owing to large data gaps. This hampers effective management actions and interferes with conservation efforts in the region. Five sea turtle species occur in Northwest Africa (i.e. green turtle Chelonia mydas, hawksbill Eretmochelys imbricata, leatherback Dermochelys coriacea, loggerhead Caretta caretta and olive ridley Lepidochelys olivacea). The region has regionally and globally important sea turtle nesting and foraging habitats and is a global fishing hotspot, with high and increasing fishing pressure. Available information on sea turtle bycatch in Northwest Africa was compiled from peer‐reviewed and grey literature from 2010 onwards to determine the impact of artisanal and industrial fisheries (by gear type) on regional sea turtle populations and assess the level of threat to individual species. All sea turtle species occurring in the region are impacted by bycatch. Reports suggest that green turtles and loggerheads have the highest bycatch rates, probably owing to their regional abundance and widespread distribution. Some of the potentially highest reported global bycatch rates (14,000–90,000 turtles/year/country) are noted, particularly in gillnets, longlines and handlines. However, further research is needed to understand mortality levels from artisanal fisheries and assess the impact of trawl fisheries operating in the region. Additional sources of mortality include deliberate capture for consumption or trade. To strengthen regional sea turtle conservation and reduce sea turtle bycatch and mortality, urgent action is needed to implement and enforce national protection, establish a bycatch reduction framework (including gear modifications and spatio‐temporal closures), improve fisheries data collection and build capacity.

Junk food: A preliminary analysis of ingested marine debris by hawksbill Eretmochelys imbricata and olive ridley Lepidochelys olivacea sea turtles (Testudines: Cheloniidae) from the eastern coast of the United Arab Emirates

For the first time, the qualitative and quantitative characteristics of marine debris ingested by six hawksbill (Eretmochelys imbricata) and seven olive ridley (Lepidochelys olivacea) sea turtles from the Gulf of Oman coast of the United Arab Emirates were investigated. The numeric and gravimetric proportions of ingested marine debris obtained from the esophagus, stomach and intestines were quantified following categories of presumed sources, Marine Strategy Framework Directive (MSFD), rigidity, color and plastic polymer types. Marine debris was observed in 28.6% of olive ridley (x̅: 2.00 items; 4.83 g) and 83.3% of hawksbill specimens (x̅: 6.00 ± 2.32 items; 0.32 ± 0.24 g). Overall, the results of this preliminary study suggest that hawksbill sea turtles were ingesting marine debris at higher frequencies and that plastics were observed to be the most predominant debris ingested. However, non-plastic rubbish, particularly metallic fishing gear (fish hooks and fish traps), were observed to present lethal hazards for both species.

Satellite tracking of rehabilitated sea turtles suggests a high rate of short-term survival following release.

The rehabilitation of wildlife can contribute directly to the conservation of threatened species by helping to maintain wild populations. This study focused on determining the post-rehabilitation survival and spatial ecology of sea turtles and on comparing the movements of individuals with flipper amputations (amputees) to non-amputee animals. Our aims were to assess whether rehabilitated sea turtles survive after release, to compare and contrast the movement characteristics of the different species of sea turtles we tracked, and to examine whether amputees and non-amputees within species behaved similarly post-release. Twenty-six rehabilitated sea turtles from four species, including hawksbill Eretmochelys imbricata (n = 12), loggerhead Caretta caretta (n = 11), green Chelonia mydas (n = 2), and olive ridley Lepidochelys olivacea (n = 1) sea turtles from the United Arab Emirates were fitted with satellite tags before release. Rehabilitation times ranged from 89 to 817 days (mean 353 ± 237 days). Post-release movements and survival were monitored for 8 to 387 days (mean 155 ± 95 days) through satellite tracking. Tag data suggested that three tracked sea turtles died within four days of release, one after 27 days, and one after 192 days from what are thought to be anthropogenic factors unrelated to their pre-rehabilitation ailments. We then compared habitat use and movement characteristics among the different sea turtle species. Although half of all turtles crossed one or more international boundaries, dispersal varied among species. Loggerhead turtles had a high dispersal, with 80% crossing an international boundary, while hawksbill turtles displayed higher post-release residency, with 66% remaining within UAE territorial waters. Amputee turtles moved similarly to non-amputee animals of the same species. Loggerhead turtles travelled faster (mean ± sd = 15.3 ± 8 km/day) than hawksbill turtles (9 ± 7 km/day). Both amputee and non-amputee sea turtles within a species moved similarly. Our tracking results highlight that rehabilitated sea turtles, including amputees, can successfully survive in the wild following release for up to our ~one-year monitoring time therefore supporting the suitability for release of sea turtles that have recovered from major injuries such as amputations. However, more broadly, the high mortality from anthropogenic factors in the Arabian Gulf region is clearly a serious issue and conservation challenge.

Trialing net illumination as a bycatch mitigation measure for sea turtles in a small-scale gillnet fishery in Ecuador

In Ecuador, one of the main hazards for threatened marine species, such as sea turtles, is small-scale fisheries bycatch. At a global scale, currently, bycatch reduction technologies (BRTs) are being tested in many coastal nations to mitigate this issue. Despite some advances in Ecuadorian efforts for wildlife protection, BRTs to reduce bycatch have yet to be assessed. The purpose of this study was to test the BRT of net illumination using violet light-emitting diodes (LEDs) as a mitigation measure to reduce sea turtle interactions in the small-scale driftnet fishery operating from the ports of Santa Rosa, Puerto Lopez and Jaramijo. A total of 146 pairs of experimental sets (control and illuminated panes) were deployed in all ports. A generalized linear mixed-effect model (GLMM) was employed to analyze the bycatch per unit of effort (BPUE) for sea turtles, and the catch per unit of effort (CPUE) for target species; for both control and illuminated panes. Thirty-two sea turtles from three species were observed captured: olive ridley Lepidochelys olivacea (n=18), green Chelonia mydas (n=13) and leatherback turtles Dermochelys coriacea (n=1). Turtle species-specific modeling showed bycatch of green turtles declined by 93% in illuminated nets compared with control, non-illuminated nets, whereas no significant difference between control and illuminated nets was observed for olive ridley turtles. The catch per unit effort of the target pelagic fish species including skipjack tuna, yellowfin tuna, mahi-mahi, thresher shark and smooth hammerhead shark was not affected by net illumination. Our results represent the first evaluation of the effects of net illumination using LEDs on reducing marine turtle bycatch in Ecuadorian small-scale driftnet fisheries. Despite its relatively small sample size, these results could be used by fisheries managers to support the implementation or further testing of this BRT in gillnet fisheries along the Ecuadorian coast.

The Sustainable Ecotourism Potential Development With Special Reference to Oliveridley Sea Turtle (Lepidochelys olivacea) Along Bantul Beaches, Indonesia

All seven species of sea turtle are endangered species, Olive ridley Lepidochelys olivacea is listed as red list of threatened species by the IUCN. From 2012 until 2018 only L. Olivacea that can be found landing at Bantul Beaches. Bantul has four beaches for sea turtle conservations; Pandansimo, Goa Cemara, Samas, and Pelangi. The purpose of this study was to obtain information on the perception of general tourists about the potential development of turtle conservation based ecotourism in Bantul. A questionnaire by random sampling used to collect data to respondents (200 visitors). The data processed using quantitative descriptive. SWOT analysis methods use to evaluate the possibility of sea turtle based sustainable ecotourism developtment. The results show that almost of tourist perception about: the condition of the beach in Bantul that is positive; the responses of the beach operators were good; approve of turtle conservation based ecotourism development; agree with the policy to donate for the efforts of turtle conservation; have the perception that the turtle has its attractiveness for beach tourism; agree that giving an explanation of the importance of turtle conservation before the release of hatchlings open to the tourists’ insight about the importance of turtle conservation. The area of the beach during the release of hatchlings is very supportive because of limited visitors when release hatchlings. The presence of donations by tourists in conservation efforts can be used as a source of funding for turtle conservation. From SWOT analysis, the sea turtle conservation in Bantul is potential to be developed into sustainable ecotourism.

Incidental capture of sea turtles in the artisanal gillnet fishery in Sechura Bay, northern Peru

Gillnets are recognized globally as one of the fishing gears with the highest levels of bycatch and mortality of sea turtles. Through onboard observer monitoring from July 2013 to June 2014 we assessed the bycatch of sea turtles by an artisanal gillnet fishery operating from Sechura Bay, Peru. One hundred and four sea turtles were incidentally caught in 53 observed fishing sets. The observed species composition of bycatch was green turtle Chelonia mydas (n = 100), hawksbill Eretmochelys imbricata (n = 3) and olive ridley Lepidochelys olivacea (n = 1). Bycatch occurred in 62.3% of monitored sets, with an average of 1.96 turtles caught per set. For all sea turtles combined, 28.8% of individuals were dead and 71.2% were alive at the time of retrieval. The majority of individuals caught were classified as juveniles and sub-adults, with an average carapace length (CCL) of 57.3 ± 0.9 cm for green turtles and 40.2 ± 2.4 cm for hawksbills. The mean annual catch per unit effort (CPUE) of sea turtles was 1.11 ± 0.31 turtles km -1 12 h -1 ), but varied by seasons. These results suggest that Sechura Bay is an important developmental habitat for juvenile and sub-adult green turtles and hawksbill turtles, but one subject to intense fishing interaction pressure. The development of monitoring programs, local awareness-raising activities, and enhanced management and protection of this critical foraging area and developmental habitat is recommended.

Effects of hook and bait in a tropical northeast Atlantic pelagic longline fishery: Part I—Incidental sea turtle bycatch

The interaction between tuna fisheries and sea turtles is commonly recognized as one of the major threats and causes for the decline of sea turtle populations. Within the tuna and swordfish fisheries, the incidental sea turtle bycatch is usually more frequent from longline fisheries targeting swordfish. Therefore it is important to test possible mitigation measures, particularly in areas where fishing activities and high abundance of these species overlaps, as is the case of the Tropical Northeast Atlantic Ocean. Between August 2008 and December 2011, a total of 202 experimental pelagic longline sets were carried out in that region (latitude: 11–22°N, longitude: 20–38°W). The aim was to test the effects of changing the traditional J-style hooks (10° offset) baited with squid used by the fishing industry, against two circle hooks (one non-offset and one with 10° offset) and mackerel bait. Four sea turtle species were captured, with the leatherback Dermochelys coriacea comprising most of the bycatches (BPUE, bycatch per unit of effort using the traditional configuration of 0.990 turtles/1000 hooks), followed by three hardshell species: the loggerhead Caretta caretta and the olive ridley Lepidochelys olivacea (BPUE=0.165 turtles/1000 hooks), and the Kemp ridley Lepidochelys kempii (BPUE=0.024 turtles/1000 hooks). In general, the sea turtle interactions in the fishery can be reduced by changing from the traditional gear to one of the experimental combinations. However, those reductions were species-specific, with the leatherback bycatches reduced only when changing from J-style to the non-offset circle hook, while for the hardshell turtles both the hook style (using a circle hook, with or without offset) and the bait (using mackerel) significantly reduced the incidental bycatches. Hooking location was also species-specific, with most hardshell specimens hooked by the mouth and esophagus, while leatherbacks were mostly hooked externally by the flippers. Most of the sea turtles were captured and released alive with the mortality rates independent of the hook style and bait type used. A reduction of 55% in leatherback incidental bycatches can be expected in this fishery by changing from J-style to circle hooks, whereas for the hardshell species a 50–59% reduction can be obtained by changing to circle hooks (respectively with and without offset), and a 55% reduction by using mackerel bait.

Patterns and inferred processes associated with sea turtle strandings in Paraíba State, Northeast Brazil.

This study analysed sea turtle strandings on the coast of Paraíba State, Northeastern Brazil, from August 2009 to July 2010. A total of 124 strandings were recorded in this period: green turtle Chelonia mydas (n = 106), hawksbill Eretmochelys imbricata (n = 15), olive ridley Lepidochelys olivacea (n = 2) and loggerhead Caretta caretta (n = 1). Of all turtles for which the Curved Carapace Length (CCL) was measured (n = 122), only 12 individuals (9.7%) were adults. Twenty individuals had synthetic anthropogenic debris in the gastrointestinal tract. Other traces of human interactions were observed in 43 individuals, such as injuries caused by entanglement in fishing lines or nets, collisions with vessels, direct contact with oil spills and lesions caused by sharp or spiked objects. Moreover, in 28.5% of the stranded turtles, the presence of external tumors was noticed, suggestive of fibropapillomatosis and in 9.7%, shark bite marks were observed. Of the 107 individuals that were sexed, 76 were females and 31 were males. Most turtles (72.6%) became stranded during the spring/summer (between October and March). We found evidence of human interactions (injuries) in half of the strandings, but in most cases it was not possible to determine if such interactions were the cause of death. A logistic regression found a significant relationship between CCL, ingestion of debris and lesions caused by sharks or spiked objects. Systematic data collection from stranded sea turtles can provide useful biological information, such as seasonal and spatial patterns in their occurrence and mortality, age structure, sex ratio and diet, as well as possible mortality causes.

Hox gene expression in the embryonic genital system of the sea turtle Lepidochelys olivacea (Eschscholt, 1829), a species with temperature-dependent sex determination

Hox genes are conserved transcription factors which regulate embryonic morphogenesis and differentiation. For the first time, we examined the quantitative and spatial expression of two Hox 5′ genes, HoxD11 and HoxA13, in the developing genital system of the olive ridley Lepidochelys olivacea, a species with temperature-dependent sex determination. Quantitative and spatial expression patterns of both genes suggest a role in the female pathway rather than the male pathway. For instance, both genes, especially HoxA13, were expressed in the undifferentiated gonad during the thermosensitive period at a female promoting temperature, and downregulated in the differentiated gonad. By contrast, expression of both genes was low in gonads incubated at a male promoting temperature and did not change significantly in the differentiated gonad. Furthermore, we found high expression levels of HoxA13 in the paramesonephric duct at the male promoting temperature but not at the female promoting temperature, suggesting a role for this Hox gene in the partial regression of the Müllerian duct in males.

Nesting estimation and analysis of threats for Critically Endangered leatherback Dermochelys coriacea and Endangered olive ridley Lepidochelys olivacea marine turtles nesting in Congo

Six marine turtle species are reported from the coastal waters of the Republic of the Congo. Among them, nesting by the Critically Endangered leatherback Dermochelys coriacea and Endangered olive ridley Lepidochelys olivacea marine turtles occurs annually from September to April on Congolese beaches. We developed a methodology to model the nesting season of marine turtles and apply it to the time series of nest counts for six nesting beaches monitored over 2–4 years. There is a peak of nesting activity in early January for leatherback turtles and early December for olive ridley turtles. We show a decline of olive ridley nests during this period whereas leatherback nesting increased, and propose that differential threats for these two species explain such a contrasted pattern.

Nesting and at-sea distribution of marine turtles in Angola, West Africa, 2000–2006: occurrence, threats and conservation implications

AbstractThe status of marine turtles in Angola, West Africa, is poorly known, and therefore during 2000–2006 a combination of both dedicated and opportunistic beach and at-sea turtle surveys were carried out, and interviews conducted with fishing communities and at markets. Green Chelonia mydas, olive ridley Lepidochelys olivacea, leatherback Dermochelys coriacea and loggerhead turtles Caretta caretta were recorded, and nesting of the first three species confirmed during September–March (peaking November–December). Green turtles nested mainly in the south, leatherback turtles in north and central Angola, and olive ridley turtle nesting was widespread. Olive ridley turtle nest density at Palmeirinhas averaged 32 nests km−1. At-sea surveys produced 298 turtle records, with peak occurrence during August. Significant anthropogenic-related mortality (including exploitation of meat and eggs and fishing bycatch) was recorded, in addition to natural predation and other threats. Maintenance of the long-term sustainability of these turtle populations should focus on the involvement of fishing communities and increasing awareness throughout Angola.

Migration routes and foraging behaviour of olive ridley turtlesLepidochelys olivaceain northern Australia

The foraging ecology of endangered olive ridley Lepidochelys olivacea sea turtles is poorly known in Australia, with only a limited knowledge of their foraging distribution inferred from captures in trawl net fisheries. We attached satellite transmitters to 8 olive ridley turtles in 2004 and 2005 at a nesting beach in Australia's Northern Territory to document their migratory routes and for- aging behaviour. Three turtles moved up to 40 km from the nesting beach before renesting on the same beach within 12 to 23 d. The turtles made post-nesting migrations of 165 to 1050 km to 5 differ- ent foraging areas and used coastal, continental shelf and continental slope habitats. The use of one foraging area by 3 turtles, together with previous trawl data, indicate a predictable source of food in this area. Distinct foraging areas indicate that foraging behaviour differs from the meandering oceanic movements of turtles in the Pacific. During migration and foraging periods, turtles dived to the substrate with maximum depths of 150 to 200 m and maximum dive durations of 120 to 180 min. The locations of foraging areas overlapped with existing trawl fisheries and oil and gas exploration and mining.

The panmixia paradigm of eastern Pacific olive ridley turtles revised: consequences for their conservation and evolutionary biology

Previous studies of the olive ridley Lepidochelys olivacea population structure in the tropical eastern Pacific have indicated the existence of a single panmictic population ranging from Costa Rica to Mexico. This information has been used to design specific management measures to conserve primary nesting beaches in Mexico. However, little is known about olive ridleys in the Baja California Peninsula, their northernmost reproductive limit, where recent observations have shown differences in nesting female behaviour and size of hatchlings relative to other continental rookeries. We used mtDNA control region sequences from 137 turtles from five continental and four peninsular nesting sites to determine whether such differences correspond to a genetic distinction of Baja California olive ridleys or to phenotypic plasticity associated with the extreme environmental nesting conditions of this region. We found that genetic diversity in peninsular turtles was significantly lower than in continental nesting colonies. Analysis of molecular variance revealed a significant population structure (Phi ST = 0.048, P = 0.006) with the inclusion of peninsular samples. Our results: (i) suggest that the observed phenotypic variation may be associated with genetic differentiation and reproductive isolation; (ii) support the recent colonization of the eastern Pacific by Lepidochelys; (iii) reveal genetic signatures of historical expansion and colonization events; and (iv) significantly challenge the notion of a single genetic and conservation unit of olive ridleys in the eastern Pacific. We conclude that conservation measures for olive ridleys in Mexico should be revised to grant peninsular beaches special attention.

Timing of SOX9 downregulation and female sex determination in gonads of the sea turtle Lepidochelys olivacea.

The SRY-related gene SOX9 is involved in the differentiation of Sertoli cells in male gonads of vertebrates with different kinds of sex determination. In the olive ridley Lepidochelys olivacea, a species with temperature sex determination (TSD), the SOX9 protein is expressed at stages 21-24 in medullary cells in gonads of embryos incubated at both male-(MPT) or female-promoting temperatures (FPT). However, at FPT the expression of SOX9 protein decreases at stage 25 and disappears at stage 26, suggesting this as the critical period for SOX9 regulation by temperature. Here, we used reverse transcriptase polymerase chain reaction (RT-PCR) to detect SOX9 transcripts in gonads of embryos switched from MPT to FPT at stage 23 and sampled at days 6-14. Simultaneously, groups of embryos were switched back to MPT and gonadal sex was established. SOX9 transcripts were detected at days 6-12 of switching, when embryos reached stage 25 and were no longer detected at day 14, when the embryos were at stage 26. Embryos switched back to MPT at days 6 or 8 formed testes, whereas embryos switched at days 10 or 14 developed ovaries. Results suggest that at MPT the male sex-determining pathway that maintains SOX9 expression in male gonads is established at stage 24. In contrast, at FPT, the female sex-determining pathway involved in downregulation of SOX9 in female gonads occurs within two days at stage 25. J. Exp. Zool. 290:498-503, 2001.

Response of diencephalon but not the gonad to female-promoting temperature with elevated estradiol levels in the sea turtle Lepidochelys olivacea.

Although temperature sex determination is well known in several reptile species, the physiological mechanism underlying this process remains to be elucidated. In the current work, we analyzed the levels of testosterone (T) and estradiol (E2) in the gonads; two brain regions--telencephalon (Te) and diencephalon/mesencephalon (Di)--and the serum of developing embryos of the olive ridley Lepidochelys olivacea incubated at male- or female-promoting temperatures. Conversion of pregnenolone (P5) to T and T to E2 were studied in the gonads and brain. The analyses were performed during three periods: the thermosensitive period (TSP), histologically undifferentiated gonads (UDG), and differentiated gonads (DG). In the gonads, serum, and brain, T concentrations were higher at the female-promoting temperature during the three periods, whereas in the gonads and serum, E2 levels were similar at the female and male-promoting temperature. In Di, the concentration of E2 was significantly higher at the female-promoting temperature. Biotransformation of P5 to T in gonadal tissues were slightly higher at the female-promoting temperature in TSP and increased during UDG and DG. Conversion of T to E2, however, was similar at the two temperatures during the three periods. In the brain, the Di showed a higher efficiency for transforming T to E2 at the female-promoting temperature. Our present results do not allow us to decide whether the diencephalon is the cause or the effect, but they conclusively demonstrate that, in L. olivacea, this region of the brain senses temperature during sex determination.

The incidental capture of five species of sea turtles by coastal setnet fisheries in the Eastern waters of Taiwan

The incidental capture of sea turtles by the coastal setnet fisheries in Eastern Taiwan was investigated. Five species of sea turtle were caught — in declining order of abundance, green Chelonia mydas, loggerhead Caretta caretta, hawksbill Eretmochelys imbricata, olive ridley Lepidochelys olivacea, and leatherback Dermochelys coriacea. Green, loggerhead and olive ridley sea turtles used the east coast waters of Taiwan as their benthic habitats. Most of the captured turtles were sold to be subsequently released in religious ceremonies. Although none of the turtles were drowned in situ, the setnet fisheries could have a negative impact on their populations. Some mitigating recommendations are made.

The sinister snail : E. Murray, Endeavour, 17(2), 1993, pp 78–83

The incidental capture of sea turtles by the coastal setnet fisheries in Eastern Taiwan was investigated. Five species of sea turtle were caught — in declining order of abundance, green Chelonia mydas, loggerhead Caretta caretta, hawksbill Eretmochelys imbricata, olive ridley Lepidochelys olivacea, and leatherback Dermochelys coriacea. Green, loggerhead and olive ridley sea turtles used the east coast waters of Taiwan as their benthic habitats. Most of the captured turtles were sold to be subsequently released in religious ceremonies. Although none of the turtles were drowned in situ, the setnet fisheries could have a negative impact on their populations. Some mitigating recommendations are made.

Sea turtles of Madagascar – their status, exploitation and conservation

Five species of sea turtles are known from Madagascar's coastal waters. Fishermen on the western and south-western coasts take green turtle Chelonia mydas, loggerhead turtle Caretta caretta and olive ridley Lepidochelys olivacea for their meat. The hawksbill turtle Eretmochelys imbricata is taken mainly for its shell and for making stuffed specimens while the leatherback Dermochelys coriacea is seldom caught. Anecdotal evidence of fishermen and dealers in turtle products, measurement of captured animals and personal observations of the authors all point to declines in numbers and average size for green and hawksbill turtles, coupled with marked declines in nesting rates for these and the olive ridley.

Surveys of the sea turtles of Angola

Five species of sea turtles have been reported from Angola (in decreasing order of abundance): leatherback Dermochelys coriacea, olive ridley Lepidochelys olivacea, green Chelonia mydas, loggerhead Caretta caretta, and hawksbill Eretmochelys imbricata. All have been reported to nest on Angolan beaches, although with varying frequency. Immature, subadult and adult sea turtles have been recorded foraging along the coastline of Angola and in bays which provide developmental habitats. Few data are available on the distribution and abundance of each species in these habitats. The level of exploitation of turtles in Angola is moderate, as no dedicated turtle fishery exists. If, however, exploitation is considered to include those turtles taken by incidental catch, it would be deemed heavy. All size classes of turtles and eggs of some species have been taken incidentally although it has been reported that eggs are deliberately hunted. Even though sea turtles have been protected under Angola's hunting laws since 1972, and a heavy fine has existed since that time to discourage exploitation, little enforcement has occurred.

Rearing the Olive ridley Lepidochelys olivacea in artificial sea water

International Zoo YearbookVolume 26, Issue 1 p. 90-94 Rearing the Olive ridley Lepidochelys olivacea in artificial sea water S. PAULRAJ, S. PAULRAJ Assistant Conservator of Forests.Search for more papers by this authorS. SUBBARAYALU NAIDU, S. SUBBARAYALU NAIDU Director, Arignar Anna Zoological Park. Madras-600048. IndiaSearch for more papers by this authorJ. PAKKIARAJ, J. PAKKIARAJ Ranger, Arignar Anna Zoological Park. Madras-600048. IndiaSearch for more papers by this author S. PAULRAJ, S. PAULRAJ Assistant Conservator of Forests.Search for more papers by this authorS. SUBBARAYALU NAIDU, S. SUBBARAYALU NAIDU Director, Arignar Anna Zoological Park. Madras-600048. IndiaSearch for more papers by this authorJ. PAKKIARAJ, J. PAKKIARAJ Ranger, Arignar Anna Zoological Park. Madras-600048. IndiaSearch for more papers by this author First published: January 1987 https://doi.org/10.1111/j.1748-1090.1987.tb03140.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Volume26, Issue1January 1987Pages 90-94 RelatedInformation