Do morning and afternoon bird surveys have the same results? A case of bird survey in Dramaga Campus, IPB University, Indonesia

Abstract

During bird surveys using the point count technique, observers assume that early morning and late afternoon observations will have the same result. This assumption is rarely tested prior to the field observation. This paper’s objective was to compare morning and afternoon bird counts in Dramaga Campus, IPB University. Bird data were collected at 6-8 am and 3-5 pm using a standard point count method in four different habitat types: forest, riparian, plantation, and built-up areas. The number of species, bird abundance, as well as Shannon indices (H’) and their corresponding t-tests were calculated. There were 52 bird species found in all habitat types. Time-wise, the number of species found was very similar (morning: 47 species, afternoon: 46 species). H’ in all habitat types were slightly differed between both times, non-significant by t-tests (H’ in morning and afternoon: forest 2.64, 2.66; plantation 2.33, 2.34; built-up area 2.43, 2,55; riparian 2.38, 2.30; t-test values were 0.28, 0.17, 1.42, 0.52, P>0.05 for all comparisons). Bird abundance was also similar between morning and afternoon counts. Based on this result, the assumption that morning observation is the same as afternoon observation can be accepted as a replication of bird survey in the study area.