Background

Action Sheet

  • Location :
    Anhui province, China
  • Species status :
    Critically endangered
  • Period :
    May 2011 - May 2016

Sponsor

The Chinese alligator (Alligator sinensis), one of the world’s most endangered crocodilians, and is the only species endemic to China.


It is listed by the IUCN as Critically Endangered and included within Appendix I of CITES.

Fossil evidence and literature on the subject suggest that the Chinese alligators were once widely distributed in the lowland areas and rivers of China. By the middle of the nineteenth century, they were present throughout the lower Yangzi River valley in southeastern China. Currently, Chinese alligators are now restricted to a few small isolated areas in southern Anhui Province and in adjacent Zhejiang Province. Recent field surveys suggest that not more than 120 alligators remain in the wild and the population continues to decline. The principal factor contributing to the decline of the species is habitat loss.

To increase the number of Chinese alligators in the wild, additional sites for the establishment of new populations will have to be identified and restored, and captive-bred alligators reintroduced. The technique of reintroducing crocodilians to their natural habitat has already proven successful in several countries. The Chinese government is now very interested in the reintroduction of the alligators.  From 2006 to 2010, thirty-six captive- bred alligators were released at Gaojingmiao Forest Center in Langxi County in Anhui Province. They were all accurately measured by radio-telemetry. The reintroduced alligators have laid five nests, while forty-nine babies have hatched.

Research on the Chinese alligator’s habitat selection was performed during the whole of the re-introduction process and a considerable amount of habitat preference data was collected. The research team now intends to screen between three and five potential habitats along the lower Yangzi River and to reintroduce captive-bred Chinese alligators there using GIS as well as remote sensor techniques.

Selected captive-bred Chinese alligators will then be released at the chosen reintroduction sites. The Anhui Normal University research team expects that there should be over 300 alligators living in natural habitats within three to five years with very little human intervention. Should this objective be achieved, the species will have a high probability of survival and the risk of extinction would be greatly reduced. The implementation of this program will bring great hope for this emblematic species in China.

To determine which site is most suitable to release the Chinese alligator, it is necessary to understand what is needed for the survival of the species.  Researchers at Anhui University analyzed the habitat of Chinese alligators and showed that bank shelter conditions, pH value of the water area, snail abundance, bamboo abundance, and water stability were significant elements in the survival of the alligators. Bank shelter condition was shown to be especially important. The observations in the field also confirmed this and released individuals tended to choose the edges of banks that were in good condition with significant vegetation cover.

The above results however referred mostly to microhabitats and a larger approach is needed in order to determine the Chinese alligator´s “ideal” habitat and factors such as human impact, landscape characteristics (slope, aspect) etc. should also be considered. Habitat suitable index modeling should then be used to help screen the potential habitat areas, together with maps from GIS technology, to help environmental managers make appropriate decisions. Remote sensors and GIS have provided further support for the establishment of the Chinese crocodile reintroduction model.

REFERENCES

  • K Bovee and JR  Zuboy. 1988. Evaluation of habitat suitability, criteria. In Proceedings of the workshop development, volume 88, US. Fish, Wildlife Service, Biological reports
  • BL Brooks and SA Temple.  1990. Hahitat availability and suitability for loggerhead shrikes in the upper midwest.  American Midland Naturalist, 123: 75–83
  • Gage H. Dayton and Lee A. 2006. Fitzgerald. Habitat suitability models for desert amphibians. Biological conservation, 132: 40–49
  • Antoon de Vos. Crocodile conservation in India.  1994. Biological Conservation, 29(2): 183 – 189. ISSN 0006-3207. doi: DOI:10.1016/0006-3207(84) 90076-4.
  • M Debeljak, S Dzeroski and K Jerina.   2001. Habitat suitability modeling for red deer (Cervus elaphus  l.) in south-central  Slovenia with  classification  tree.  Ecological Modeling, 138: 321–330
  • You-Zhong  Dingand  Xiao-MingWang.  2004. Factors influence the population status of wild Chinese alligators (Alligator sinensis).  Biodiversity Science, 12 (3): 324–33
  • You-Zhong Ding, Zheng-Huan Wang and Jian-ShengWu. Observation of activity in Chinese alligator released during an early period at Hongxing of Anhui.  Zoological research, 25(1): 27–31, 2003.
  • CK Dodd and RA Seigel. 1991. Relocation, repatriation and translocation of amphibians and reptiles:  Are they conservation strategies that work?  Herpetologia, 47(3): 336–350
  • Roland F. Graf, Lukas Mathys, and Kurt Bollmann. 2009. Habitat assessment for forest dwelling species using lidar remote sensing:  Capercaillie in the Alps.  Forest Ecology and Management, 257: 160–167
  • GJ  Rolof and  BJ  Kernohan. 1999. Evaluating reliability of habitat suitability index models. Wildlife Society Bullet, 114: 287–304
  • Henrik Skova, Elizabeth Humphreysb, Stefan Garthec, and Kerstin Geitner.  2008. Application of habitat suitability modeling to tracking data of marine animals as a means of analyzing their feeding habitats. Ecological modeling 212: 504–512
  • PS Soorae.  2008. Global re-introductionperspectives: reintroduction case studies from around the globe. viii+284 pp, IUCN/SSC Re-introduction Specialist Group, Abu Dhabi, UAE
  • Giacomo Tavecchia, Covadonga Viedma, and Miguel-Angel Bartolom Alejandro  Martnez-Abran.  2009. Maximizing re-introduction success:  Assessing the immediate cost of release in, a threatened waterfowl.  Biological conservation, 14: 3005–3012
  • JW Terrel.   1984. Fish habitat suitability index models.   In Proceedings of the workshop, volume 85, U.S. Fish and wildlife service, Biological Reports.
  • John Thorbjarnarson and Xiao-Ming Wang.  1999. The conservation status of the Chinese alligator.  Oryx, 33(2): 152–159
  • John  Thorbjarnarson,  Xiao-Ming  Wang,  Shao  Ming,  Lijun  He,  Youzhong  Ding,  Yuelong Wu,  and  Scott  T.  McMurry.   2002. Wild populations of the Chinese alligator approach extinction. Biological Conservation, 103(1): 93–102. ISSN 0006-3207. DOI: 10.1016/S0006-3207 (01)00128-8
  • Simone Vincenzi, Graziano  Caramori, RemigioRossi, and GiulioA. De Leo. 2006. A GIS-based habitat suitability model for commercial yield estimation of tapes philippinarum in a
  • Mediterranean coastal lagoon (Cacca  di Goro, Italy).   Ecological modeling, 193: 90–104
  • Rongsheng  Wen.  2001. The rise and fall of Alligator sinensis and vicissitudes of environment. Nature Magazine, 22(1): 55–58
  • Lu-Sheng Wu, Xiao-Bing Wu, Hong-XingJiang, and Chao-Lin Wang.  2005. Habitat characteristics of wild Chinese alligator (Alligator sinensis). Biodiversity science, 13(2): 156–161

Field operator

Anhui Normal University

Founded in 1928,Anhui Normal University is not only an institution of higher learning but also one of the earliest universities in the Anhui province. The university has 16 colleges,7 doctorate programs,71 post graduated programs,55 undergraduate programs.So far,there are 35000 students from different countries in the world,more than 2200 workers and staff members,among them are 550 full and associate professors.

www.ahnu.edu.cn

Objectives

OBJECTIVES

  1. Establish selection habitat criteria and potential reintroduction habitats for the Chinese alligators
  2. Perform field surveys to determine the species´ potentially appropriate habitats
  3. Recover potential release areas to enable the reintroduction of the animals
  4. Reintroduce captive-bred Chinese alligators into the wild
  5. Carry out the post-release monitoring of the released individuals and manage the release sites



Actions

1. Establishment of habitat selection criteria

In order to undertake the reintroduction of the species into the wild, general habitat criteria should first be established so as to be able to define the specific habitat factors required by this Chinese alligator.   The criteria should encompass biological requirements (water quality, food resource, soil condition, vegetation) and socio-economic requirements (human interference, pollution, their impacts on agriculture and on local humans, opinions of local people on the proposed reintroduction project).

The results will be established taking account of the conclusions of the study by the Gaojinmiao Forestry Center and also of the knowledge of experts. Determining the alligators’ habitat preference will be especially important. The different habitat factors in particular locations will then be rated against these defined alligator preferences, taken as representing the most suitable natural environment.

2. Selection of potential habitat

The potential habitat along the Yangzi River will be screened according to the previously defined criteria using topographic maps and satellite images.  More than fifteen habitat factors will be considered, such as elevation, slope, aspect, vegetation, hydrological environment, residents etc. Each factor will be rated according to the previously defined criteria and the locations mapped.  Finally, weighted factors will be overlaid and the most suitable habitats will be indicated in the graph.

3. Field survey for potential reintroduction habitats

The potentially suitable habitats may be considered as potential reintroduction sites, requiring however confirmation from further field surveys.

Several line transects will be established at different random intervals from the center of the study area.  Those transects will cover all habitat types.  The composition and the density of the natural vegetation in the study area will be recorded and combined with satellite pictures and updated surveyed results so as to create a dynamic index.

The species and biomass of the animals  (especially aquatic fauna) will be identified and measured in selected plots on the transects. The hydrological condition will be analyzed using water quality analyzers, and soil samples will be collected to analyze the pH value and salinity levels

4. Preparation of selected release sites

The selected release sites still need to be improved in order to suit the Chinese alligator´s habitat requirements. Some residents should therefore be removed from the habitat areas. Some sites will also have to be dug up to supply the appropriate hydrological conditions, while some others will require additional food sources.  The research team aims to have 3-5 suitable habitat areas by the second year.

5. Re-introduction of captive-bred Chinese alligator

Healthy captive-bred Chinese alligators will be selected and pedigree analyses will be performed using micro-satellite markers. Field survival training for the chosen alligators will be undertaken before release. Some alligators will be equipped with radio-transmitters so that they may be monitored. When the reintroduction sites are ready, the selected alligators will be released into the wild.

6. Tracing and management

During the post-release period, management of the release sites and alligators are both important. The education activities need to be strengthened for the implementation the Wildlife Protection Law. Local authority representatives, family heads, local company representatives, students, and teachers inhabiting the proposed re-introduction sites will be given the opportunity to meet with the team of wildlife biologists. Informal workshops will be conducted to inform the participants on the area´s threatened and endemic species and raise pride of local biological heritage within the communities. A structured survey investigating the knowledge, values, attitudes, and perceptions towards the Chinese alligators’ recovery program, will be implemented by the different governmental agencies.

Participants will be given a structured questionnaire. Pre-testing will be conducted on few communities prior to the study to ensure that all questions are clear, and a final version will prepared for sampling. The released individuals will need to be traced by radio-transmitters in order to observe their post-release fate.

Proposed Research Timetable

Sept 2010–Apr 2011:

  • Literature review
  • Data collection
  • Establishment of habitat criteria

May 2011–Sept 2011:

  • Screening of potential reintroduction habitat
  • Field survey to select release sites
  • Selection of alligators to be released

Oct 2011–May 2013:

  • Habitat recovery of the release sites
  • Field survival training for the alligator to be released
  • Selection of Chinese alligators by DNA analysis

Jun  2013–Dec 2015:

• Tracing and management of released alligators

• Report writing

News

- In January, 2013 -

Release of six Chinese alligators

Last summer, six alligators have been selected from the breeding centre, according to the results of several health tests (length and body measures, traumatism examination). The 2 males and 4 females have been equipped with radio transmitters in order to ensure scientific monitoring and they have been released on the Gaojingmiao site, which was restored in 2011.

Alligator equipped with a transmitter on its tail before being released © Anhui N. University

- In September, 2012 -

Last summer, the team of Anhui Normal University (in China) identified an alligator nest made by an individual previously reintroduced in Gaojingmiao site. A nice indicator of success of the reintroduction program!

Discovery of the nest in Gaojingmiao (© Anhui Normal University)

- In March, 2012 -

Chinese alligator habitat restoration starting

Since the end of last November, scientists from the University of Ahnui started the restoration of the Chinese alligator habitat. They plan to release individuals in the wild all through 2012.


- In September, 2011 –

A highlight for the reintroduction of the Chinese alligator!

On July 26th, a small alligator appeared in one of the ponds where Chinese alligators have been reintroduced. It was the first time that the research team observed a baby alligator in these pool areas. The baby alligator was about two years old and measured about 28-32 centimeters.

This was great progress for the reintroduction process of Chinese alligator as it showed that eggs can hatch and that babies can survive by themselves in the wild.


- In August, 2011 -

Mating season for the Chinese alligators

Mid-June to mid-July marked the period of heavy rains in area of the Yangtze River. This period is traditionally known in China as the “rains of the plum season”.It is also the mating season for Chinese alligators.

At the beginning of June, the Anhui Normal University research team heard the alligators´ bellowing and observed the male, who had been released several months previously, court a female by snout touching. The researchers also found traces of nest-making behavior and hope to be able to find viable nests of the species in the next few months.

The radio transmitters are working well!

The radio transmitters, which had been placed on the three Chinese alligators released early May, have been found to be working well and the research team encountered no problems in locating all of the crocodilians. The alligators are still at the release pool site and looking well.

One of the released individuals was found to prey on a small animal, possibly a frog. This is very positive news as it firstly shows that the released individuals still have retained their natural hunting instinct and are able to live well in the wild.

Photos Gallery

Alligator chinois
Alligator chinois
Alligator chinois

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