Foraging behaviour and population status of the white-breasted cormorant (Phalacrocorax lucidus) in lake Hora- Arsedi, Bishoftu, Ethiopia

Abstract

The present study was conducted at Lake Hora-Arsedi located in Bishoftu town, 47 km south of Addis Ababa. The aim was to investigate the dive duration, pause duration, perching height, foraging band and population status of the white-breasted cormorant (Phalacrocorax lucidus) in the study area. Two sites were selected to carry out the observations. Data were collected from January–December 2014 to include dry and wet seasons mainly based on direct observational methods. Focal observations were carried out on randomly selected foraging cormorants within the two systematically oriented observation sites. A single individual was observed for 20 minutes. Total population count was made at two roosting sites along the shoreline following roost count technique. Roost count was made 15 times at each season. The total number of population during wet and dry seasons was 23 ± 0 .4125 and 33 ± 0.43498. The mean dive duration at site 1 during the dry season was 22.32 ± 0.84 and 30.3 ± 0.75 seconds during the wet season. The mean dive duration at site 2 during the dry season was 25.76 ± 0.68 seconds and it was 39.25 ± 0.96 during the wet season. The mean dive duration at both sites showed significant variation between seasons (P<0.05). Dive duration and pause duration were significantly positively correlated in both sites during both seasons. Dive efficiency ranged from 1.67 to 2.26. Mean perching height ranged from 1.8 ± 0.15 to 2.3 ± 0.25 and the variation was not significant. Mean foraging band ranged from 11.56 ± 0.91 to 22 ± 1.2 m and the variation was significant between sites of the same season (P<0.05) but was insignificant between seasons of the same site (P>0.05).

Key words/phrases: Bishoftu, Dive duration, Foraging band, Great cormorant, Pause duration.