Are there more mosquitoes if the swifts leave earlier?

Dear Ms Kaiser

Thank you very much for your enquiry regarding swifts and mosquito populations.

Climate change is altering the migratory patterns of swifts

Extreme temperature fluctuations and early heatwaves mean that many swifts are now returning to Europe from their African wintering grounds up to two weeks earlier – often as early as April instead of early May. Their departure in late summer is also shifting earlier in some cases, from early August to late July. In addition, the returning birds are increasingly struggling with a shortage of nesting sites and a lack of food.

Fewer insect hunters, more mosquitoes

A link between the swifts’ early return and a perceived increase in swarms of mosquitoes can be explained as follows: A single common swift catches many thousands of insects a day – including mosquitoes, flies and others. When the large swarms suddenly disappear at the end of July or beginning of August, one of the most effective insect hunters is suddenly missing from the air. If the weather is then warm and humid in late summer, the mosquito population can literally explode, because their natural predators are already on their way to Africa. Some local authorities are therefore resorting to chemical control measures once again.

I hope this information is of help to you. Otherwise, I’d be happy to assist you further.

Kind regards

Marc Limat

Sources:

• BUND Hessen: The common swift – when climate change alters a bird’s rhythm
• Süddeutsche Zeitung: Swifts affected by climate change
• Die Zeit: Swifts are returning – housing shortage and lack of food
• Swiss Ornithological Institute, Sempach: Common swifts
• LBV: Common Swifts begin their return journey
• VSVB: Swift tower
• Märkische Oderzeitung: Slubice relies on chemicals to tackle mosquitoes