Threats in Tenerife are increasing due to all kinds of human factors and disruptive elements in ecosystems.
An overpopulation of pigeons, illegal housing, and disruption of ecosystems are among the causes that negatively affect unique bird species, such as the Bulwer’s petrel.
The Bulwer’s petrel is under pressure and requires urgent, sustainable policy measures to prevent further decline. The cause of this is an overpopulation of pigeons due to an abundance of food and shelter provided by humans.
The overpopulation of pigeons in Tenerife, as a result of human activity, has become a threat in Tenerife to the Bulwer’s petrel (Bulweria bulwerii), a small seabird with which they compete for nesting on rocks and cliffs. This is revealed by a study conducted in the colonies of the petrel on the Canary island, in which Airam Rodríguez, researcher at the National Museum of Natural Sciences (MNCN-CSIC), and members of the Ornithology and Natural History Group of the Canary Islands (GOHNIC) and SEO/BirdLife participated.
Pushed Back
Pigeons, whose numbers have increased due to the easy food and shelter they obtain from humans, are displacing this seabird from cliff areas, islets, and coastal rocks on the island. These areas function as sanctuaries, as the birds try to escape predators such as cats and rats introduced by humans.
At the same time, the pigeons are also moving into these remote zones to settle, as fewer predators are present there. The study results show that this competition for nesting sites is the most common cause of breeding failure in the Bulwer’s petrel (7.3%), a higher percentage than rat predation (6.3%). Although it seems minor, 7% is relatively high, especially considering that these birds have already been pushed into very isolated areas.
Nesting Sites
During monitoring checks, petrels were found incubating eggs, but during a later check, their nests were occupied by a pigeon. This finding implies that the nest is lost, as petrels and shearwaters (procellariiformes), the group of seabirds to which they belong, form lifelong pairs and reuse the same nest for years — sometimes up to 40 years.
It was also observed that rocks where no pigeons were present at the time of the study had a higher density of petrels, indirectly supporting the hypothesis. The problem goes beyond competition for nesting sites, as pigeons can also transmit diseases to these seabirds and their droppings can cause changes in local vegetation, warns the expert.
Human Factor
Among the factors promoting the increase in pigeon numbers and their potential threat in the Canary Islands are the large availability of food — both in cities and indirectly via agricultural and livestock activities — as well as the easy shelter they find, particularly in abandoned buildings where they can nest.
Another factor is colombophilia (pigeon racing), the collection of techniques and knowledge related to breeding pigeons, a deep-rooted tradition in the Canary Islands. One of its practices involves releasing pigeons hundreds of kilometers away, from another island or even from open sea, to time which returns fastest to the loft. Of the pigeons released, a portion ultimately establishes itself in the wild, and this forms part of the threats in Tenerife.
Conservation Challenges
The complexity of studying seabirds, partly due to difficult access to areas such as rocky cliffs or a lack of funding, should not be underestimated. The purpose of the study is to raise awareness of this issue and to explore how the problem can be resolved.
Among the measures that could be taken to improve the situation are removal of pigeons or installation of nesting boxes that pigeons cannot enter due to their larger size compared to petrels.
That the pigeon population is increasing depends primarily on humans, who are responsible for changing environmental conditions in such a way that this kind of explosive growth in bird species becomes possible.
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Threats in Tenerife ©
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