The municipality of Kaiseraugst has been fighting the crow problem in the Liebrüti housing development for years. Now the canton has granted an exemption: The birds' nests may be removed even during the closed season.

The Kaiseraugst municipal office still receives weekly e-mails and letters on the subject of crows in the Liebrüti housing development. The birds have been causing a great deal of annoyance among residents for years. Their squawking wakes some people from their sleep early in the morning and disturbs them in the evening and into the night.

The municipality has therefore been pursuing the so-called three-pillar concept - food deprivation, deterrence and decimation - for some time. "We have taken measures in all areas of the concept. This has had an effect, but unfortunately only in the relatively short term in each case," says local councillor Jean Frey. The birds always returned - and with them the complaints. "Understandably so," says Frey.

The crows should look for other nesting places

Now the municipality wants to go one step further. It has received an exemption from the canton for the removal of the crows' nests, beyond the closed season for crows that actually begins on February 16. "No more nests may be removed until egg-laying has taken place," says Erwin Osterwalder, specialist in hunting and fishing at the canton.

"This is a deterrence measure with the aim of shifting the breeding of crows to the forest areas outside the settlement," says Frey. There are suitable trees along the Violenbach and in the direction of the highway, and the potential for disturbance is much smaller there. Such or similar exceptional permits are rarely granted. "We are very restrictive about granting permits for nest removals and only grant them if other measures have been implemented first, as Kaiseraugst has done," Osterwalder says. "We also always consult with BirdLife Aargau before issuing a permit."

However, the rook population has established itself in Kaiseraugst within a short time and has grown rapidly. Osterwalder has already seen the situation for himself on site. He justifies the exceptional permit:

"The crows breed in the middle of the residential area. The associated noise pollution and area-wide fecal contamination exceed tolerable levels there."

There are no empirical values for this measure. But Osterwalder is quite confident that it could have an effect in the longer term. "It is not lethal, but it is a very strong intervention in the breeding behavior of the birds." He says the canton will remain in contact with the municipality to monitor how the situation develops.

A drone with a gripper arm is to grab

A specially developed drone with a gripper arm will be used for nest removal. It comes from the company Eagle Eye Multicopter Services GmbH. The company has already been active in the past two years for crow control in Liebrüti - with the robotic falcon "Robird".

Last week, a test flight was conducted with the drone. "It worked," says Jean Frey.

Video unter www.eagle-ey.ch/trans-fly

In February, when the crows start building their nests, the drone will be used. The trees will then be checked weekly and the nests continuously removed, says Frey.

"The goal is to prevent large-scale egg-laying from occurring in the first place, but for the birds to move to other locations to do so."

The corresponding contract with the company is currently being prepared. In the 2021 budget of the municipality are also reserved several tens of thousands of francs for crow control.

Disposal company installs nets over the sweepings

Another measure is to make it even more difficult for the crows to obtain food. Thus, the crows' accesses to the waste disposal company in the REWAG area will be closed with nets in the evenings and on weekends, and the containers will be covered. The corresponding building permit from the municipality has been obtained. "We hope that we will now find ways to solve the problem in the long term as well," says Jean Frey.