Broad-snouted Caiman - Caiman latirostris.

In: Crocodiles.Status Survey and Conservation Action Plan: 18-22.
Third Edition, ed. by S.C. Manolis and C. Stevenson. Crocodile Specialist Group: Darwin

Aus dem Inhalt:

The Broad-snouted caiman is a medium-sized crocodilian. Although its maximum reported size is 3.5 m,  animals longer than 2.0 m are presently rare in the wild. This species’geographic distribution includes the drainages of the Paraná, Paraguay,  Uruguay  and  São  Francisco  River  systems, spreading  over  regions  of  northeast  Argentina,  southeast Bolivia, Paraguay, and northern Uruguay. It also includes a large number of small Atlantic coast drainages from Natal, at the eastern tip of Brazil, to northeast Uruguay. Although this species is eventually sympatric with C. yacare
, Medem (1983) reported that C. latirostris was generally found in more densely vegetated, quieter waters. In Paraguay, Scott et al. (1990) found C. latirostris to be a habitat generalist, but when in sympatry with C. yacare it tended to be found in more ephemeral habitat, and was a better colonizer of isolated cattle stock ponds. This kind of man-made habitat has been also reported to be colonized by the species in Brazil (Verdade  and  Lavorenti 1990) and Argentina (Venturino 1994). Urbanization is also a threat, especially in eastern Brazil, but the species can still be found in urban lakes of the southern region of Rio de Janeiro City (Freitas-Filho 2007). Caiman latirostris has also been found in the mangroves of coastal islands of southeast Brazil (Moulton 1993). According to Yanosky (1994), the Broad-snouted caiman can be found from sea level up to 800 m altitude. 

Spectacled Caiman - Caiman crocodilus.

In: Crocodiles.Status Survey and Conservation Action Plan: 10-15.
Third Edition, ed. by S.C. Manolis and C. Stevenson. Crocodile Specialist Group: Darwin

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The Spectacled caiman is the most widely distributed of the New World crocodilians, ranging from southern Mexico in the North to Peru and Brazil in the South. It is also the most geographically variable species in the Americas, with four subspecies generally being recognized.

Caiman appear to have been quite resilient to commercial hunting for a number of reasons, but particularly because they reproduce at a relatively small size, and hunting in many areas seems to have been concentrated on larger adult males. Another important factor has been the near extirpation of larger, sympatric species of crocodilian of greater commercial value. For example, caiman in Brazilian Amazonia occupy habitats that were formerly dominated by Melanosuchus niger.

Longevity of Crocodilians in Captivity.

International Zoo News  Vol. 61. No. 5 (2014), pp. 363-373

Introduction:

Since  1978  the  author  has  collected  numerous  records  on  animal  longevities. This data has been collected during personal examination of archives at zoological collections worldwide and through correspondence with zoo staff members. Taxonomy  in  this  list  follows  that  used  in  the  publications  of  the  Crocodile Specialist Group of the IUCN.

This paper is the first comprehensive listing for every species and subspecies of crocodilian for which the author has a verified and known longevity record, including initial date of entry (hatch, capture, arrival) and a known date of death and/or verification as still living. Documentation of longevities at the subspecies level has  not  been  included  in  previous  treatments  of  the  Crocodilia.  Anecdotal  records  have not been accepted.

weigl-biblio

American Alligator - Alligator mississippiensis.

In: Crocodiles. Status Survey and Conservation Action Plan. Third  Edition, ed. by S.C. Manolis and C. Stevenson. Crocodile Specialist Group: Darwin:: 1-4.

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The American alligator is the outstanding example of the application of sustainable use for the successful conservation of a crocodilian species. Although heavily exploited since the 1800s, and considered to be endangered in the early 1960s, populations have responded well to management and have recovered rapidly. Extensive surveys of alligator populations have been undertaken throughout the species’ range. Continuous monitoring of numerous localities is conducted as part of sustainable use programs in several states. Overall, alligator populations are quite healthy. Owing to expanding human populations, programs to control alligators that occur near people and dwellings (termed “nuisance” alligator control) are an integral part of alligator management and conservation. In some states, near the periphery of the alligator’s distribution, alligator populations are less dense and they are completely protected. The current total wild population is estimated to be 2-3 million alligators.

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Conservation of the Sunda gharial Tomistoma schlegelii in Lake Mesangat, Indonesia.

International Zoo Yearbook 49: 137–149. ISSN 0074-9644.DOI: 10.1111/izy.12068.

Abstract:

Although featured in many international zoo collections for decades, little was known about the natural history of Sunda gharial Tomistoma schlegelii until recently. Zoos rarely keep large individuals and breeding success has been low. As late as 1998, even though most conservationists regarded the conservation status of the species as Endangered, the reality was that over most of the range the actual status of the Sunda gharial was Data Deficient. Beginning with surveys of the species by international and local scientists in Indonesian Sumatra and, later, in Kalimantan, Indonesian Borneo, supported by the International Union for Conservation of Nature/Species Survival Commission Crocodile Specialist Group, more details on the broad distribution of this crocodilian came to light. Ironically, rediscovery of a large and healthy population of T. schlegelii in East Kalimantan arose from an oil-palm company accessing the area to develop a site called Danau Mesangat. Subsequently through a cooperation agreement with the oil-palm company's conservation department and a local foundation, a group of dedicated zoos in Europe and America, and the Tomistoma Task Force set up by the Crocodile Specialist Group, provided funding for three consecutive years of field studies by a research group. These studies investigated the ecology of T. schlegelii and of a sympatric population of the Critically Endangered Siamese crocodile Crocodylus siamensis. The role of the zoos, including their role in the development of the research programme, is described. Accounts are given of the characteristics of the Mesangat habitat, some new details about the distribution and abundance of Sunda gharial and Siamese crocodiles in the habitat, and information about reproduction in T. schlegelii. In summary, an overview of threats and suggestions for conservation actions needed at the Mesangat site are provided.

The importance of genetic research in zoo breeding programmes for threatened species: the African dwarf crocodiles (genus Osteolaemus ) as a case study.

International Zoo Yearbook 49: xx-xx.ISSN 0074-9664 (Print) ISSN 1748-1090 (Online).

Abstract:

The threatened African dwarf crocodiles (genus Osteolaemus) are distributed throughout West and Central Africa. Traditionally two subspecies were described (Osteolaemus tetraspis tetraspis and Osteolaemus tetraspis osborni), although recent molecular studies demonstrate the presence of three allopatric lineages that should be recognized as full species. These highly divergent taxa are distributed in the three major forested biogeographic zones of western Africa: Congolian (Osteolaemus osborni), Lower Guinean (Osteolaemus tetraspis) and Upper Guinean (Osteolaemus sp. nov. cf. tetraspis). Largely because of their diminutive size, dwarf crocodiles are regularly kept in zoos and aquariums worldwide. In Europe, the collection is managed by a European studbook coordinated by Leipzig Zoo, Germany, since 2006, while American zoological institutions do not yet manage these species as part of a studbook programme. To facilitate ex situ conservation efforts, it is important to identify accurately each individual to the appropriate species following the latest systematic understanding of the genus. Population aggregation analysis with mitochondrial and nuclear gene sequences was used for both species identification and detection of interspecific hybridization. The results of our study show that only European collections house all three Osteolaemus  taxa, although only a single individual O. osborni  was confirmed. The most prevelant species present in both European and North American institutions was O. tetraspis. Additionally, several O. sp. nov. cf. tetraspis were identified, likely originating from the Senegambia region, especially in the North American collections. This will represent an important resource for future conservation efforts as Osteolaemus  are highly threatened in this region of West Africa. Unfortunately, both zoo populations showed relatively high frequencies (c. 25–28%) of hybridization between O. tetraspis a nd O. sp. nov. cf. tetraspis bred in captivity. We highly recommend that zoological institutions ensure they know the species identity of the Osteolaemus they maintain and work together to transfer individuals into single-species colonies to avoid further hybridization. In the USA, this may necessitate the creation of a studbook programme. It may also prove valuable to consider a cooperative programme between the European Association of Zoos and Aquaria and the Association of Zoos & Aquariums, wherein each Association focuses its resources largely on a single Osteolaemus  species. This would, however, require trans-Atlantic transfer of individuals. The case study of dwarf crocodiles in zoological institutions reinforces the importance of genetic research in conservation-breeding programmes, highlights the potential for collaboration between European and American zoological institutions for the ex situ conservation of threatened wildlife, and foreshadows some of the regulatory challenges in managing captive populations internationally.

schmidt-biblio

First observations on the courtship, mating, and nest visit behaviour of the Philippine crocodile (Crocodylus mindorensis) at the Cologne Zoo.

Abstract

The aim of this study was to gain a better understanding of the social and in particular reproductive behaviour of the Critically Endangered Philippine crocodile. Crocodylus mindorensis has been a focus for international conservation breeding measures for about two decades. Since little scientific data have been gathered on the biology and ecology of the species so far, its breeding remains a challenge.

In order to identify behavioural patterns that trigger courtship behaviour, and to determine when sociopositive interactions increase and the animals are ready for reproduction, a pair of two adult C. mindorensis at Cologne Zoo was systematically observed between August 2011 and July 2012 for a total of 583 hours. Observations took place using all occurrences recording and scan sampling, focusing on pre-, post- and actual mating behaviour. We present a detailed documentation of copulations with behaviours such as growling, roaring, and bubbling. Bubbling in both sexes was observed prior to copulations and decreased with the end of the mating season, supporting the assumption that it can be referred to as courtship behaviour. Behaviours that indicate the approach of the breeding season, such as approaches to the dividing slide, bubbling and nest building, could be distinguished. Our findings should help to improve breeding efforts under captive husbandry conditions and thus contribute to the conservation breeding of this highly endangered and difficult to keep crocodilian species.

jzar - Journal of Zoo and Aquarium Research 2(4): 123-129.

Crocodiles in the Sahara Desert: An Update of Distribution, Habitats and Population Status for Conservation Planning in Mauritania.

PLoS ONE. 6 (2)
Published: February 25, 2011. DOI: 10.1371/journal.pone.0014734

Background

Relict populations of Crocodylus niloticus persist in Chad, Egypt and Mauritania. Although crocodiles were widespread throughout the Sahara until the early 20th century, increased aridity combined with human persecution led to local extinction. Knowledge on distribution, occupied habitats, population size and prey availability is scarce in most populations. This study evaluates the status of Saharan crocodiles and provides new data for Mauritania to assist conservation planning.

Methodology/Principal Findings

A series of surveys in Mauritania detected crocodile presence in 78 localities dispersed across 10 river basins and most tended to be isolated within river basins. Permanent gueltas and seasonal tâmoûrts were the most common occupied habitats. Crocodile encounters ranged from one to more than 20 individuals, but in most localities less than five crocodiles were observed. Larger numbers were observed after the rainy season and during night sampling. Crocodiles were found dead in between water points along dry river-beds suggesting the occurrence of dispersal.

Conclusion/Significance

Research priorities in Chad and Egypt should focus on quantifying population size and pressures exerted on habitats. The present study increased in by 35% the number of known crocodile localities in Mauritania. Gueltas are crucial for the persistence of mountain populations. Oscillations in water availability throughout the year and the small dimensions of gueltas affect biological traits, including activity and body size. Studies are needed to understand adaptation traits of desert populations. Molecular analyses are needed to quantify genetic variability, population sub-structuring and effective population size, and detect the occurrence of gene flow. Monitoring is needed to detect demographical and genetical trends in completely isolated populations. Crocodiles are apparently vulnerable during dispersal events. Awareness campaigns focusing on the vulnerability and relict value of crocodiles should be implemented. Classification of Mauritanian mountains as protected areas should be prioritised.

Nachzucht bei den Neuguinea-Krokodilen  (Crocodylus novaeguineae Schmidt, 1928) im Zoologischen Gartens Wuppertal.

Der Zoologische Garten (N.F.) 68 (6): 332-336. VEB Gustav Fischer Verlag Jena. ISSN: 0044-5169

Zusammenfassung:

Zwei Neuguinea-Krokodile schlüpften am 31. V. 1998 im Zoologischen Garten wuppertal. Es handelt sich um die erste gelungene Nachzucht in einem Zoologischen Garten.

Voller Text

schürer-biblio

Danau Mesangat und Indonesiens letzte Siamkrokodile.

Z. Kölner Zoo 55 (2012): 133-139.

Zusammenfassung:

Der Mesangat in Ostkalimantan auf der Insel Borneo ist ein Sumpfgebiet mit einzigartiger Artenvielfalt und viele bedrohte Tierarten sind in dem teilweise bewaldeten Feuchtgebiet zu Hause. Das Gebiet ist eines der letzten Rückzugsorte des seltenen und vom Aussterben bedrohten Siamkrokodils in Indonesien. 2010 und 2011 konnten bei zwei vom Kölner Zoo mit initiierten Feldaufenthalten Erkenntnisse zum Status der Population und zur Ökologie der Tiere gewonnen werden. Um die Population am Mesangat auch in Zukunft nachhaltig zu schützen, ist dabei insbesondere die Zusammenarbeit mit der einheimischen Bevölkerung vor Ort von großer Wichtigkeit.

Summary:

Danau Mesangat in East Kalimantan on the Island of Borneo is a swamp area with a very unique biodiversity. These partly forested wetlands are home to many threatened species. The area is one of the last known refuges of the rare and critically endangered Siamese crocodile in Indonesia. In 2010 and 2011 two field visits, which were initiated amongst others by the Cologne Zoo, I could obtain information on the population status and on the ecology of these animals. For the future conservation of the population at Mesangat the cooperation with local people on site is of special importance.