Visual ecological impact of a peculiar waste oil lake on the avifauna: Dual-choice field experiments with water-seeking birds using huge shiny black and white plastic sheets

B. Bernáth, G. Szedenics, G. Molnár, G. Kriska, G. Horváth

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Since 1951 there has existed a waste oil lake in Budapest (Hungary). This oil lake acted as a huge bird trap for 50 years. Prior to its removal, from August, 1997 to March, 1998, a monitoring was performed to observe and document the carcasses of the birds trapped by the oil. This oil lake is an analogy of the crude oil lakes in the desert of Kuwait and the ancient/recent natural asphalt seeps and tar pits that acted/act as massive animal traps. To study the visual attractiveness of shiny oil surfaces to birds, we performed dual-choice field experiments in every August from 1997 to 1999. We imitated the oil by means of a huge, shiny, black plastic sheet laid onto the ground, while the brighter surface of certain natural water bodies was mimicked by means of a huge, shiny, white plastic sheet. We observed the birds and their reactions to these plastic sheets. Water-seeking birds could be visually deceived by and attracted to shiny plastic sheets. They apparently mistook the shiny surface of these plastic sheets for water or a wet muddy surface. At the plastic sheets the deceived birds showed quite a similar behaviour as at natural water bodies or muddy areas. A black kite tried to drink from the white plastic sheet. A great white egret preferred the white plastic sheet to the black one. Swallows considered the plastic sheets as water, or feeding, or mire-gathering place. During flight or after landing, they tried to drink mainly from the white plastic sheet. They hunted the attracted insects more frequently above the black plastic sheet. The behaviour of wagtails at and on the plastic sheets was the same as that at real water bodies or wet muddy surfaces. Wagtails preferred the black plastic sheet. The black plastic sheet was three times as attractive to white storks as the white plastic. The storks made such movements with their bills as it is observable at the birds searching in the mud. Starlings avoided the plastic sheets if they landed directly close to them in the grass. Our field experiments showed that the optical cues of the shiny surface of open-air oil reservoirs may be so strong that water-seeking birds are visually compelled to remain in the immediate vicinity of the oil in spite of the fact that other senses signal that it is not water. Thus, the deceived birds try to drink from the oil, or land directly on the oil surface, or wade into the oil, or try to catch the insects attracted to the oil surface. The consequence of all these reactions is, at least, a single contact with the sticky oil, which is enough to be trapped or to become oiled, the necessary aftermath of which is death. That is why the open-air oil reservoirs are so extremely dangerous for water-seeking birds. Birds of prey are also in danger of being trapped by the oil when they try to feed on the carcasses of other trapped birds. Also insectivorous birds are endangered to be trapped, which try to catch the insects attracted to the oil surface. The study of the visual ecological impact of oil lakes on the avifauna is the prerequisite of the necessary environmental protective arrangements that should be urgently taken in order to eliminate any man-made oil spills and open-air oil reservoirs. The dangerous impact of these oil lakes to birds is demonstrated by the estimation that the waste oil lake in Budapest trapped about 13-17 thousands birds during the 50 years of its existence.

Original languageEnglish
Pages (from-to)1-28
Number of pages28
JournalArchives of Nature Conservation and Landscape Research
Volume40
Issue number1
Publication statusPublished - Jan 1 2001

Keywords

  • Avifauna
  • Bird trap
  • Birds
  • Plastic sheets
  • Visual deception
  • Waste oil lakes
  • Water detection
  • Water imitation

ASJC Scopus subject areas

  • Ecology
  • Nature and Landscape Conservation

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