Mirror fencer

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This chaffinch cannot distinguish its reflection in the window pane from an alleged rival in its territory.
Summer cardinal on a car window
House sparrow fencing against the window pane

Male birds are referred to as mirror fencers who, especially during the breeding season, knock their beak against windows or mirrors and thus fight their mirror image as supposed rivals. In the English-language area, the phenomenon, first described in 1879 as a shadow boxing is ( English shadow boxing ), respectively.

problem

Young titjay
Blue tit on a motorcycle mirror

Birds occupy a territory during the breeding season and thus secure the food base for rearing their young. If an alien conspecific intrudes into the breeding area, it is threatened, attacked and, if possible, driven away. Many birds cannot recognize their reflection as such (see mirror test ). Like many other animal species, they consider their reflection to be a rival who needs to be attacked and driven away. So they hit the window with their beak. In German-speaking countries, it is mostly bird species that live around houses, such as wagtails , chaffinches , blackbirds , house sparrows and carrion crows . Larger species such as magpies or crows can damage the window seals. This behavior has been documented in almost 200 species worldwide. Broken window panes are even known from Jägerliesten and southern ground hornbills . Even if the birds usually do not injure themselves, it means additional stress during the breeding season. The phenomenon occurs especially in the breeding season between March and June, with corvids sometimes all year round. After the young birds have hatched, mirror fencing usually also disappears.

Defense measures

The only way to combat the phenomenon is to prevent reflection . For window panes on the house, the following is suitable:

  • Close the roller shutter or
  • Attach a cardboard box, fabric, foil or fly screen to the outside of the lower part of the disc during the breeding season or
  • spray the outside of the pane with decorative spray.

Some advisers recommend cleaning the window panes less often during the breeding season, as a light layer of dust prevents the birds from reflecting in it. Attaching bird of prey silhouettes, however, has proven to be pointless.

reception

In July 2016, the white stork " Ronny " from Glambeck in Brandenburg attracted nationwide attention as a notorious mirror fencer. The reporting in this case can be seen as a typical summer slump story.

literature

Web links

Commons : Spiegelfechter  - Collection of images, videos and audio files

Individual evidence

  1. ↑ a b c d e Joël Roerig: Shadow boxing by birds - a literature study and new data from southern Africa . In: Ornithological Observations , ISSN  2219-0341 . Volume 4, June 4, 2013, pp. 39-68.
  2. ↑ Taichi Kusayama, Hans-Joachim Bischof, Shigeru Watanabe: Responses to mirror-image stimulation in jungle crows (Corvus macrorhynchos) . In: Animal Cognition , Volume 3, Number 1, May 2000, pages 61-64, doi : 10.1007 / s100710050051 .
  3. ↑ a b c d Spiegelfechter - Fight against the mirror image , State Association for Bird Protection in Bavaria , accessed on February 18, 2019.
  4. ^ Joël Roerig: Shadow boxing . In his article from 2013 Roerig speaks of 79 species (p. 49).
  5. ↑ a b Bird death on glass surfaces on nabu.de. Retrieved on February 14, 2019.
  6. ↑ a b Hans Schmid: Spiegelfechter. Swiss Ornithological Institute & SVS / BirdLife Switzerland, Sempach and Zurich, 2012, accessed on February 10, 2019 .
  7. ↑ Birds and Window Panes. In: bfvhh.wordpress.com. October 9, 2017, accessed February 14, 2019 .