Science alumnus Jacques de Satge wins second Ornithology prize 'Wim Dings - De Wielewaal'
24 Jan 2017 - 15:45
Many popular garden birds appear to thrive in our cities and towns. But is their presence also sustainable?
Poor success of birds breeding in urbanised areas
Jacques de Satge, UCT BSc alumnus and current Masters student at the University of Antwerp, studied the breeding success of great tits in nest boxes in a large number of Flemish cities and towns. In his Master's thesis he reports that the number of fledged young per nest is up to 30% lower in the most urbanized areas compared to forests in rural areas.
"In addition the fledged young weigh about 10% less which further reduces their survival chances", says de Satge. "Great tits also start laying earlier and produce fewer eggs, but still the success per egg is lower."
Caterpillars in short supply
Previous studies had already shown that great tits and other songbirds raise fewer young in urban areas. What is new in this study is that the effect is not limited to major cities. Birds breeding in a park in the middle of a small town have equally poor success. What seems to be most important is the degree of urbanization within a few hundred meters around the nest. "Video registrations show that parents provision their young with significantly fewer caterpillars in urbanized areas compared to rural areas. This is probably due to the lower abundance of indigenous trees such as oaks. These trees can harbour huge caterpillar populations exactly when the nestlings are growing."
The good news is that great tits are still abundant in Flanders without sign of a negative trend: the large productivity in forested areas probably compensates for the low success in cities. De Satge: "City parks and gardens may function as an 'ecological trap' that attracts new breeders in every successive generation thanks to its seemingly attractive vegetation with safe nesting sites. But in the end these birds fail to produce enough young to maintain their numbers."
South African de Satge did his research as part of the international Masters in Biodiversity at the University of Antwerp. His Master's thesis is awarded with the Ornithology prize 'Wim Dings - De Wielewaal' worth 2000 euros. This prize is awarded every two years in remembrance of the Flemish field ornithologist Wim Dings (1927-2012), active member of the 'De Wielewaal' society. The prize aims to encourage and support research in field ornithology.
"This year's submissions were of very high quality", says Prof Erik Matthysen (University of Antwerp), chairman of the jury. "The winning thesis has high societal relevance allowing policy makers to optimize decisions on planning and management of urban greenspaces. With a South African winner the prize now also reaches an international dimension."