The Occurence of Ecological Traps in Bird Populations: Is our Knowledge Sufficient? A Review

Abstract

Anthropogenic changes in a landscape create new cues for birds, which must permanently adapt to these. If landscape changes occur too quickly, individuals have insufficient time to develop adequate reactions. They may, therefore, preferentially nest in low-quality habitats, which can lead to diminished nesting success and to reduction of their population size. This is usually termed the ecological trap hypothesis. We reviewed 38 studies investigating this phenomenon and analysed whether relationships exist between ecological trap occurrence and geographical region, habitat type, and/or life strategies of bird species. Ecological traps were most often associated with the presence of exotic species. Exotic species can modify environmental conditions in ways to which native communities are not adapted. They have been mainly detected in open habitats. Such open habitats as arable fields and meadows are under greater human pressure, and rapid changes probably occur there more frequently. Although more studies from North America were investigated, the hypothesis was supported more frequently in European studies. This is possibly due to higher human population density and, hence, more frequent habitat changes. Our results show that an ecological trap is not likely associated with migration. Ground nests suffered fewer consequences of such traps than did other nest types. Although the implications of the ecological trap hypothesis in species conservation are undisputable, a more detailed approach is still needed. For instance, some habitat types, such as suburban areas, have been neglected in the context of ecological traps, as has been the phenomenon's appearance in pristine habitats.

An update on the conservation status of the Little Bustard Tetrax tetrax: global and local population estimates, trends, and threats

“…Such rapid, iterative, and reversed changes, occurring both in the west and the east, suggests the possibility that preferred breeding habitats in agricultural landscapes act as ecological traps for Little Bustards because of agricultural practices. Ecological traps are expected to occur in rapidly changing habitats under strong anthropogenic influence (Suvorov and Svobodová 2012), such as farmland, as shown for several bird species (Donald et al 2002, Gruebler et al 2012). Breeding female Little Bustards in agricultural landscapes are attracted to temporary grasslands.…”

Camera trap data suggest uneven predation risk across vegetation types in a mixed farmland landscape

“…How do landscape features such as forests, settlements, and water bodies influence predator activity? Can narrow, linear structures act as ecological traps (Eglington et al, 2009; Rantanen et al, 2010; Suvorov & Svobodová, 2012)? Are landscapes with a lot of hedgerows more risky for ground‐nesting birds?…”

Increased lead and glucocorticoid concentrations reduce reproductive success in house sparrows along an urban gradient

“…Urban habitats have been proposed to act as ecological traps for wildlife, as these areas seem enticing because of decreased natural predators and competition for nesting sites (Demeyrier et al, 2016; Schlaepfer et al, 2002; Suvorov & Svobodová, 2013). However, these areas can be detrimental to recruitment or offspring growth, possibly exacerbated through settlement by younger age classes or less experienced individuals (Martin et al, 2014), and could lead to species extinction (Battin, 2004).…”