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  • Author: Imed Djemadi x
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Abstract

During the past two centuries, few studies have been conducted on biometrics of North African Blackbirds. Several of these studies were carried out during the latter part of the 19th and in the early 20th centuries. As a result, two subspecies were recognized namely Turdus merula algira inhabiting northern regions of North Africa and some localities in southwestern continental Europe and T. m. mauritanicus inhabiting central western Morocco and southern Algeria and Tunisia (to the end of arid climatic regions). In this study we provide morphological data from the northeastern Algerian population of Blackbird. Results reveal no differences between sexes in any of the measurements (small sample size). Comparison of morphological data of specimens collected in the northern region of North Africa and from the southern region of Maghreb countries (Algeria, Tunisia and Morocco) show morphometric differences only in wing length. These results are consistent with the existence of multiple subspecies in North African populations of Blackbird. Our findings support the assumptions of previous researchers in considering T. m. algira as typical of northern areas of Maghreb countries and T. m. mauritanicus typical of southern areas of the region.

Abstract

Although the Ferruginous Duck (Aythya nyroca) has thoroughly been studied, the foraging behaviour of this species is still not completely known. In the present paper we studied the diurnal feeding behaviour of ducks. We monitored the annual cycle of birds through two fieldtrips per month. The instantaneous behaviour of birds was recorded in regular 30-minute intervals from 7 a.m. to 4:30 p.m., amounting a total of 456 observation hours. Food searching activity corresponds to a quarter of the total diurnal time budget of the Ferruginous Duck. Foraging behaviour was classified into five categories dominated by the “diving”, which is almost 45.61% of the total search time. Foraging activities at the water surface considered to be secondary activities, including feeding by “bill”, “neck and head”, and “beak and head” in a rate of 19.86%, 14.53%, and 13.98%, respectively. The “toggle” remains a minor activity and represents only 5.99% of foraging time. The feeding behaviour of this species correlated to several environmental parameters (rainfall, temperature and wind velocity), and linked to the group size of ducks visiting the lake. Regarding the food intensity, our results show the highest values for “bill and head” behaviour. “Diving” has the longest feeding interval (16.16±14.1 minutes), while foraging by “bill” has the shortest (0.69 ± 0.48 minutes).