Guest blog by Dr Steffen Oppel, RSPB Senior Conservation Scientist, RSPB Centre for Conservation Science
New research has revealed that semi-wild northern bald ibises in Turkey that forage in certain habitats are able to raise more fledglings. RSPB and the Turkish BirdLife partner Doğa Derneği have been working together to find out how this critically endangered bird’s habitat choices affect its breeding success.
Species decline
The northern bald ibis has a very distinctive appearance with its bare red head and black spiky ruff. It used to have a much wider range around the Mediterranean and the European Alps, but has declined almost to extinction over the centuries for various reasons including land-use changes, DDT poisoning and hunting. Only two remnant populations have survived in the wild, one in Morocco, and one in southern Turkey where the birds are captive for half the year.
Reintroduction needs habitat knowledge
In the last 15 years conservationists have made great progress to re-establish northern bald ibis populations in their former range with reintroduction projects in both Austria and in Spain. For species that disappeared before scientific data recording began, it is often difficult to know what type of environment they inhabited. A re-introduction will only work if the species is introduced in an area where it can actually find food and safe nesting areas. For the northern bald ibis, very little is known about the habitat the species needs. At a recent workshop of the International Advisory Group for Northern Bald Ibis in Austria, one important conclusion was that a better understanding of the habitat requirements is a top research priority for the species.
Photo of northern bald ibises foraging in manure in southern Turkey. Photo by Can Yeniyurt
Conservation in Turkey
In Turkey, the remnant population has been safeguarded by a conservation station, where birds are held in captivity during winter. This station prevents the birds from migrating through the Middle East to their traditional wintering areas in Ethiopia, a hazardous journey from which only few birds returned in recent years due to human threats such as shooting. But during the summer, when the birds breed on the cliffs at the station, the birds can roam around the landscape to find food.
Photo of the cliff where northern bald ibises breed along the river Euphrates near the city of Birecik in southern Turkey. Photo by Can Yeniyurt
Mint plantations appear to be good foraging habitat
Together with experts from the RSPB, the Turkish BirdLife partner Doğa Derneği has now examined which habitats the northern bald ibis uses during the breeding season, and whether birds using certain habitats raise more fledglings than others. In a study published in the journal Bird Conservation International, Can Yeniyurt, Steffen Oppel, and colleagues report that birds that foraged more frequently in mint plantations and on short grasslands covered in manure were able to raise more fledglings. They also found that birds required less effort to capture prey in those habitats, and the easier foraging may have boosted their breeding success. Conversely, there was no indication that birds relied exclusively on the artificial food provided at the breeding centre, and most birds attended less than half of the feeding events, and there was no indication that attending more feeding events increased the productivity of pairs.
Photo of northern bald ibises foraging in a mint cultivation in southern Turkey. Photo by Can Yeniyurt
Using the results to find potential new reintroduction sites
The Turkish population has grown steadily from only a handful of birds in the early 1980s to now more than 200 birds, but the population is still vulnerable because it is confined to a single breeding site. With the new information about suitable habitat from the latest study, we can now cast our eye over promising landscapes in southern Turkey where nesting cliffs and foraging habitat exist to re-establish another northern bald ibis colony.
Read the study published in the journal Bird Conservation International here.