Zoöp Observations: Egyptian Geese and filamentous algaeZoöp Observations: Egyptian Geese and filamentous algae

The first two weeks of January were exceptionally warm. At dawn you could hear blackbirds and other city birds. Omens of spring were also visible in the ponds of Het Nieuwe Instituut. On January 9, I spotted a pair of Egyptian geese courting noisily on the Auke de Vries statue in the large pond. This means that they now claimed this pond as their territory. The first chicks to enter the pond will most likely be their hatchlings. Unless, of course, another pair shows up willing to fight for the same territory. Some Egyptian geese start breeding as early as January, though most wait until March and April. The incubation period of the eggs is four weeks. I do believe that the first claimants of the large pond have started breeding.

In recent weeks however, it's become clear the pair has been spending nights on the wooden deck board of the cafe. Today I swept up their droppings. Close inspection of these droppings showed that the pair has mainly lived on a diet of Spirogyra filamentous algae; the cellular structures of these algae were clearly visible in the goose droppings. Last year Spirogyra algae were a real pest in the pond. Hopefully, the growth of these algae will be contained this year by biological enemies – not only by freshwater fish like rudd and perch, that were released in November, but also by the dabbling of the Egyptian geese.

So far I haven't been able to discover the Egyptian geese's nest. It is not uncommon for Egyptian geese to occupy and refurbish the nest of another bird species. Today I saw a goose grazing on the lawn along the Rochussenstraat opposite the Nieuwe Instituut. It could well be that this is one of the couple that has claimed the pond. Perhaps the nest is located in one of the trees along the Rochussenstraat.