A confiscation of poison dart frogs was received by
Antwerp Zoo on 21 October 2004. The frogs (580 strawberry poison dart frogs
Dendrobates pumillo, approximately 20 Dendrobates auratus and two Phyllobates
lugubris) had been transported in 200 film roll containers, and more than 100
did not survive the trip. The others were placed in containers with moist peat
and oak leaves. Reptile hobbyists and the zoo supplier were able to provide
springtails and fruit flies for the first feedings. The animals were given no
vitamin or anti-parasite treatments, as their condition was too fragile. This
proved to be the right decision, other than the 16 animals that were clearly
not going to survive, only five others did not survive the first night.
The frogs were separated by color and behaviour into sixteen different morphs and places of origin. The frogs were distributed among 15 European zoos. Sex identification was determined by whistling of the males; however subordinate males do not whistle in the presence of a more dominant one, which meant that the zoos needed to be close enough in distance that it was practical to trade misidentified animals. Laying of fertile eggs began quite quickly at Antwerp Zoo. The Strawberry poison dart frog is particularly difficult to propagate in captivity because the female produces a food sac for the young, for which no nutritional substitute has yet been found. The female stops provisioning the tadpoles when they begin developing forefeet, and at that point we placed each froglet in a separate container. We did not feed them while the mouth developed and the tail was absorbed. After another two days they were carefully fed springtails, and most of the young were successfully reared. We are very pleased with this achievement, particularly given the amphibian crisis now occurring: many species of amphibians may be dependant on captive propogation for their continued existence, at least for a time.
Grévy Zebras in Captivity
A European Endangered species breeding Program (EEP)
was initiated in 1992 for the Grévy’s zebra because this species is threatened in the wild. The EEP is
currently coordinated by Tanya Langenhorst at Marwell Zoo in the UK. The world
population at the end of 2004 included 580 Grévy’s zebras in 108 institutions,
of which 252 (94.158), i.e. 43.5% of the world captive population, were held by 31 EEP participants.
The Grévy’s zebra herd at Safaripark Beekse Bergen in
Hilvarenbeek, The Netherlands has grown significantly since its start with five
animals in 1972 (see Figure 1????). Forty-two foals have been born at the park
since 1972, and in recent years these zebras have only been allowed to breed
every other year. The breeding male is
kept out of sight of the females during non-breeding periods to keep him from
becoming restless. The male is also separated from the females for a few weeks
after birth to prevent injury to the foals when the male tries to breed the
female again.
Currently 3.8 Grévy’s zebras at Safaripark Beekse
Bergen are held in a 6 ha grass-covered enclosure with 1.7 Sable antelope and
2.9 Rothschild’s giraffe. The enclosure has sufficient room for the zebra
stallion to chase after females, which seems to be important in stimulating
reproduction. Giraffe and sable antelope young are introduced to the zebras
only under close supervision by the keepers. Low level aggressive encounters
are allowed during these introductions so that the young animals learn to keep
their distance from the zebras. The zebra mares with foals form a separate
group from the other zebras during the reproductive season. All the hoofstock
have a separate stall, except the young of the year, which remain with their
mothers. Some hoofstock, including the zebras, remain outdoors during the
summer months. When it becomes colder, the zebras want to go into their stalls.
As Safaripark Beekse Bergen has been so successful at
breeding Grévy’s zebras, less genetically-valuable animals have been moved to
other zoos and more genetically- valuable females brought to the park to
increase their likelihood of breeding. Therefore, we hope to see many young
zebras at the park in the coming years.