Dam effects on the wintering strategy and habitat use of Greylag Goose (Anser anser) in Ichkeul National Park, North Tunisia

Abstract

The mosaic of habitats in the Ichkeul National Park is frequently changing due to the variations in water conditions that had influenced the wintering strategy of waterbird populations. ). Results showed that in this area, the Greylag Goose was a regular winter visitor, typically from the beginning of October to the end of March, when food resources were totally exhausted in all marshes. Records of diurnal time budget revealed that feeding (43%) and sleeping (20%) dominated all other activities: walking, flying alertness, and preening. The food resource depletion might be the principal responsible for the total population size decreases, the behavioral changes, and the switch of habitats used by the considered species. This situation is a kind of alarm bell to indicate a perturbation of the habitats in the Ichkeul National Park. Therefore, it is essential to use appropriate management strategies to enhance the value of this area for the bio-indicator species, in particular Greylag Goose which is very sensitive to habitat changes.

Central European Greylag GeeseAnser ansershow a shortening of migration distance and earlier spring arrival over 60 years

“…Similar decreases in the total number of wintering Greylag Geese in North Africa (Hamdi et al . ) and in the number of individuals from our study area using that wintering area support the conclusion of a long‐term decrease in migration distance in this species, especially for the Central Europe/North Africa flyway. Furthermore, a northward shift in wintering distribution has also been recorded in regularly monitored wintering sites in Italy (Zenatello et al .…”

“…Suitability for wintering Greylag Geese has probably decreased in one of the previously most important wintering sites in northern Africa, lake Ichkeul (Dick et al 1991, Hamdi et al 2008a. Similar decreases in the total number of wintering Greylag Geese in North Africa (Hamdi et al 2008b) and in the number of individuals from our study area using that wintering area support the conclusion of a long-term decrease in migration distance in this species, especially for the Central Europe/North Africa flyway. Furthermore, a northward shift in wintering distribution has also been recorded in regularly monitored wintering sites in Italy (Zenatello et al 2014), which is likely to have provided alternative wintering sites in recent years.…”

“…) and environmental changes in their traditional wintering grounds (Hamdi et al . , Voslamber et al . ).…”

“…Given a similarly increasing population along the Central Europe/ North Africa migratory flyway, we could also expect similar shifts in migration behaviour in that flyway. The presence and abundance of wintering Greylag Geese is likely to be driven by local weather conditions (Musil et al 2008, Alves et al 2013, but also by their ability to exploit alternative habitats (Ramo et al 2015), their response to human disturbance (Fox & Madsen 1997, Rosin et al 2012 and environmental changes in their traditional wintering grounds (Hamdi et al 2008b, Voslamber et al 2010.…”

Exploring potential reasons for the increase in the East Asian Greylag GooseAnser anserpopulation by assessing habitat use and use of protected areas

“…During the moulting period, Greylag Geese foraged mainly on short grasslands (0.5-10 cm) in Sweden (Strong et al 2021) and foraged in the fields and meadows around lakes in south Germany to which they resort to gain safety from predators (Kleinhenz and Koenig 2018). In winter, Greylag Geese also preferred eating grain and corn in fields by day and roost on open water bodies by night in south Germany (Kleinhenz and Koenig 2018) and in the past have also been widely distributed in marshes and farmed fields around Lake Ichkeul in the Ichkeul National Park, Tunisia (Hamdi et al 2008). During the spring migration of 2007-2013, Greylag Geese used arable lands frequently in the Biebrza Basin, north-eastern Poland (Polakowski and Kasprzykowski 2016).…”