Impacts of climatic changes on small mammal communities in the Sahel (West Africa) as evidenced by owl pellet analysis

To evaluate the impact of climatic change on rodent sahelian communities, we analysed the contents of over 2500 barn owl (Tyto alba) pellets collected along the Senegal river between 1989 and 2003, and from the Ferlo sahelian area in 2003. These results are compared with data from the 1970s and 1980s in the same zones. Rodents were the most common prey (over 90%). Gerbillinae were most common in dry areas (84 to 96%) whereas in wetlands and rice fields murines were most common (77 to 88%). Nowadays, the genus Gerbillus constitutes the main prey in dry areas (77% to 88%). The genus Taterillus, which was the most abundant rodent in the Ferlo in the 1970s, now represents only 7% of rodents. Gerbils were not present in Senegal before the 1980s: G. tarabuli and G. henleyi were trapped for the first time in 1989 at the northern border of Senegal, and G. nigeriae 10 years later at the same place. The latter is now present a hundred kilometres southwards and as abundant in owl pellets as the two other gerbils.