Walsrode Birdpark Bird News

News from VogelPark - Walsrode Birdpark June 2008

 June 1st 2008 the breeding season is in full progress and numerous young birds can be seen everywhere in the park, but it is in particular behind the scenes that things are really busy at the moment. More than a third of our birds are kept off-exhibit for breeding purpose.

The notes below are a short summery of some of the developments in May:

The Bewick’s Swan, Cygnus colombianus bewicki incubated and hatched four young. This was good news as most of the other Swan species in the Park has been unsuccessful this season.

Nest-controls revealed that the colony of White-faced Whistling-ducks, Dendrocygna viduata has produced more than 60 fertile eggs up until now. As it will be a significant problem for the park to surplus all of these ducks a restriction of the breeding has been introduced by puncturing a large number of the eggs in the nests.

The single chick produced by the Magellan Goose, Chloephaga picta leucoptera is quite enough as this species is notorious for their aggressive behaviour, as any visitor coming too close to their enclosure will experience first hand. Placing the offspring can therefore be somewhat of a problem as they will invariably try to terrorize any other bird in the same enclosure.

African Pygmy-goose, Nettapus auritus male died the third loss in this species over the past few months putting our breeding-population at jeopardy. In the recent years breeding with this species has been rather successful in Walsrode, however only a single male chick was reared this year and we also lost the old main breeding female which lived for more than 25 years in Walsrode Birdpark. We now hope that a younger female will prove to be just as prolific in the long term.

Northern Cormorants, Phalacrocorax carbo were among the first birds on the large ponds to start breeding behaviour, only minutes after being released from their wintering-quarters in March they started gathering nesting material and place it in the nest baskets. Currently the three pairs are rearing 11 chicks together. The pairs consistently favour the same nesting-site year after year even though the baskets are exchanged before every spring.

In contrast to last year were the Secretary Bird, Sagittarius serpentarius produced only a single egg clutch they this year incubates a clutch with two eggs. In the previous season the pair successfully reared the one chick with out any interference. The nest-site was directly on the ground which is rather unusual. The chicks is expected to hatch in the first days of June and this year it will be a challenge for the keepers to monitor if the parents will be able to rear both chicks.

For the first time all pairs of cranes which is exhibited in the park actually nested simultaneously, not all were successful in there efforts but it was interesting for the visitors to be able to directly compare the nesting behaviour of 9 different cane species. As the fertility in different eggs are determined it is part of our management to relocate fertile eggs from genetically important birds to be fostered by other pairs that are having infertile eggs or perhaps are less important for the breeding programmes. This allows us to reduce the need for hand-rearing in cranes quite significantly. This is unfortunately not quite possible to ovoid all together, in some cases chicks must be removed when there is a health problem and not all the parent birds prove to be perfect parents. These few birds in the hand-rearing also allow us to maintain the skills needed for this aspect of the breeding. Several Cranes are still being artificially inseminated this is particular important in the birds that are pinioned and therefore not able to mate successfully themselves. During this spring 2 Grey Crowned-cranes, Balearica regulorum gibbericeps, 2 Red-crowned Cranes, Grus japonensis, 1 Hooded Crane, Grus monacha and 4 Demoiselle Cranes, Anthropoides virgo hatched so far.

Predator control is an important aspect of daily management in the birdpark but what to do when the predator is a protected species? We were both pleased and worried to discover that wild Great Eagle-owls were present in the park. These fantastic owls are making a come-back in the German landscape after being present only in low numbers for decades. An abandoned nest-mould was detected in one of the play-grounds of the park. The only reason that we are not entirely pleased with this news is that Great eagle-owls seem to have a particular liking for Waterfowl. The discovery leaves us with no other choice than providing the Waterfowl with sufficient cover. On two very dark nights we lost two Greater Flamingos, Phoenicopterus ruber roseus the necropsy proved that they had been killed by a Great Eagle-owl. Thereafter the Flamingos were provided with housing for the night which they somewhat reluctantly accepted.

The various Cuckoo species in the Park has also started breeding
The Roadrunners, Geococcyx californianus are very actively displaying and nest-building however the pair does not incubate their eggs well which is why they must be incubated artificially and subsequently hand-reared. The young Roadrunners are placed in a brooder at fairly high temperatures around 37 centigrade 24 hours after hatching. The steady diet for the young, which are fed every two hours by their surrogate parents, are based on pinky Rats. Initially only the inner organs are fed and as the chicks grow older additional diet items are gradually added to their diet.
The hatch of the first Giant Silky-cuckoo, Coua gigas of this year was exciting news that quickly turned into disappointment as the chick died a few days later. However a follow up clutch were laid and this time the chick seems to thrive and is growing at a stunning speed in the hand-rearing station.

The Sunbitterns, Eurypyga helias were disturbed on their nest by aggressive tropical ants that have been unintentionally introduced to the Tropical house many years ago. The single egg was pulled for artificial incubation and the chick hatched in mid-may. The young Sunbittern displays many behaviours and postures that we otherwise only see in adult Sunbitterns. It is quite unusual to see the small chick barely 6-8 centimetres long standing in its nest cup with its wings spread in defence-display. The Kagu, Rhynochetos jubatus which based on recent studies seem to be the nearest living relative of the Sunbittern were also scheduled to hatch this month, but unfortunately the chick died just before hatching.

The two European forms of Kestrels the Common Kestrel, Falco tinnunculus and Lesser Kestrel, Falco naumanni physically resemble each other but are strikingly different in behaviour. The semi-colonial Lesser Kestrel feeds mainly on insects where as the territorial Common Kestrel is a specialized rodent hunter. Both species currently breed in the birdpark normally both species also rear the young on their own accord without problems but unfortunately one of the male Lesser Falcons died just before the chicks in the nest he was attending were due to hatch. We decided to pull the eggs and hand-rear the young. Simultaneously the Common Kestrels decided to lay the eggs on the ground in their aviary and their eggs were also pulled for artificial incubation.
In both species the rearing is straight forward however it is crucial to provide the birds with the opportunity to socialize with their siblings. The main differences in the two species during rearing are the activity level. The Lesser Kestrels are much more active and vocal throughout the nestling-phase. We also discovered that the Lesser Kestrel can be easily sexed on hand of the upper-tail coloration with less than 4 weeks of age. Males develop a grey coloration whereas females remain barred brown on the tail.

A new arrival in May was three pairs of Black Crakes, Limnocorax (Amaurornis) flavirostris not the first time this species was kept in Walsrode but a species that has been absent from the collection since the 70ties. This small African Crake is completely black with a stunning yellow bill. They are active birds that mostly move around in the vegetation at ground-level however the quickly mover to higher ground if disturbed. The Birdpark have started an initiative with the Copenhagen Zoo in Denmark and the Antwerp Zoo in Belgium in the effort to set up several unrelated pairs of this attractive species for the purpose of long term population management.

A pair of Common Mynahs, Acridotheres tristis started nesting completely unnoticed by their keepers. This phenomenon is typically for many Starlings. The parent birds leave the nest with the slightest of disturbance and particularly when they hear the sound of the keeper pulling his key-chain out of his pocket to enter the aviary complex. This way the only indication of the Mynahs reproduction effort was the discovery of a dead chick on the ground of the aviary. For the rearing of young Starlings it is generally imperative to add additional rations of live food several times a day. The discovery of the dead chick allowed us to get ahead on developments and the two siblings are well taken care off by the parents, at least they look well fed and content with 4 additional meals a day provided in the aviary, however it was still not possible by the keepers to observe the parents actually feeding the chicks in the nest due to their secretive behaviour.

Northern Hawk-owl, Surnia ulula has only been bred sporadically at the Walsrode Birdpark in the past and is a very rare owl in European aviculture and zoos. This interesting owl is distributed in the far north. Similar to the Snowy Owl, Nyctea scandiaca their eye-sight is well adapted for the long hours of daylight in the summer. Therefore the Northern Hawk-owl can be considered almost diurnal and in the park remain one of the most active owls in the daytime. This year two pairs of Northern Hawk-owls started incubating simultaneously, one off-exhibit and the other in the new Owl-castle in the Birdpark. The female from the off-exhibit pair developed an eye infection during incubation and had to be removed for treatment. At the same time the eggs were removed for artificial incubation and hand-rearing. Also the pair in the park experienced problems as their nest-box became loose they abandoned their clutch and also here we had to remove the eggs.
The hand-rearing of the Northern Hawk-owl was reported as notoriously difficult and no reference was available for their rearing protocol. We decided for a progressive feeding strategy, due to the high level of activity in this species, and fed the chicks every two and a half hours for the first 5 – 8 days, which is unusual in owls. The strategy paid off and the young owls developed well due to a good start, however we found it to be important to reduce feedings drastically after the first 5 days down to 4 feedings a day which became the chicks well. The main food for the young owls was young Rats portioned in suitable sizes.