Activity patterns of birds in the central Free State, South Africa
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Date
2009-11
Authors
Van Niekerk, Daniƫl Johan
Journal Title
Journal ISSN
Volume Title
Publisher
University of the Free State
Abstract
Activity patterns of bird species were studied at Glen Agricultural College within the grassland
area of the central Free State, South Africa, during a period of 11 years (July 1997 - July
2008). The study focused on a specific grassland locality where 5-minute checklists were compiled
continuously from dawn to dusk at least once a week for a total of 656 days. Data were also
collected each minute for selected species. Additional observations in an adjacent tree and shrub
dominated drainage line included I-minute checklists compiled during transects over a two-year
period (late autumn 2000/1 to mid-autumn 2002/3) as well as surveys from a fixed position
from dawn to approximately 70 minutes after sunrise during 2007/8. The central aim of the
study was to quantify and explain annual, seasonal and daily activity patterns of all bird species
recorded in the study area. This data is summarised in separate species accounts where aspects
of the annual cycle, particularly breeding and moulting, were also considered. In addition, the
potential influence of rainfall was investigated.
The study reveals, for the first time, how the activity patterns of a southern African bird
community change through time, and how the amount and timing of rainfall can influence these
patterns. In spite of similarities amongst species when daily, seasonal and annual patterns
are considered separately, the study also shows that each species is unique when all its data
is considered simultaneously. Because activity patterns can have a substantial influence on
the detectability of a species, the accuracy and usefulness of surveys aimed at estimating bird
numbers is consequently questioned. The study at Glen also shows how activity patterns can be
used to help unravel the annual cycle of species in a time and cost effective way.
Description
Keywords
Activity pattern, Annual cycle, Birds, Circadian rhythm, Circannual rhythm, Drainage line, Grassland, Rainfall, Birds -- Behavior -- South Africa -- Glen, Circadian rhythms, Larks -- South Africa -- Glen, Thesis (Ph.D. (Zoology and Entomology))--University of the Free State, 2009