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Lund University (2018)

Climate change impact on grassland birds in the Mediterranean basin : a case study with the Little Bustard

Juhlin, Christina M.

Titre : Climate change impact on grassland birds in the Mediterranean basin : a case study with the Little Bustard

Auteur : Juhlin, Christina M.

Université de soutenance : Lund University

Grade : Master in Biology 2018

Résumé
There is a lot of uncertainty concerning how climate change will affect species around the World. We are already observing some ecological changes, such as European butterflies moving their range northwards. However, to predict how species will be affected by climate change is “rocket science”. This study uses GPS coordinates, satellite images and climate change projections to predict how the little bustard (Tetrax tetrax) will be impacted by climate change, by looking at how climate change will impact their habitat. The little bustard is an endangered pheasant-sized grassland bird, with important populations in Portugal and Spain. They breed in semi-arid areas of agricultural fallows and pastures, and their population has been declining for the past decades due agricultural changes. Female little bustards are the ones that choose their mate. This species has a lekking mating system, in which males form clusters of territories, from where they engage in competitive displays to attract females to come for a visit and copulate. Visitation usually occurs early in the breeding season, but females will attempt to copulate again later in the breeding season if the first offsprings don’t survive. As adults mostly eat green leaves, the start of summer droughts will drive them to migrate to post-breeding grounds. Based on various climate projections, the Mediterranean is expected to become a lot hotter and drier, which could lead males to leave their habitat sooner. To predict how much the end of the breeding season will be anticipated, we need to first understand how climate influences their habitat. GPS trackers make it possible to get a spatial representation of their territories, and with satellite images, we can determine how green their territories are when they migrate to post-breeding grounds.
This study found that aridity does affect the time window for breeding, by influencing how fast the vegetation dries up. Based on climate variables alone, this study found that the breeding habitat will dry up faster with climate change, anticipating the end of the breeding season. As the start of the breeding season has not yet been observed to start earlier, an increase of around 3ºC could potentially shorten the breeding season by 25% by 2070, from approximately 40 days to 30 days. These findings lead to a better understanding of how climate change will affect Mediterranean grassland birds with similar habitat requirements. Predicting the future is complex due to the various factors that influence and catalyse environmental change, but it is clear that quality management of protected areas, restoring fragmented habitats and developing agri-environmental schemes is important to maximise breeding success within the reduced time window.

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Page publiée le 3 avril 2019