Document


Title

Disturbance, species loss and compensation: wildfire and grazing effects on the avian community and its food supply in the Serengeti Ecosystem, Tanzania
Document Type: Journal Article
Author(s): A. K. Nkwabi; Anthony R. E. Sinclair; Kristine L. Metzger; Simon A. R. Mduma
Publication Year: 2011

Cataloging Information

Keyword(s):
  • Africa
  • arthropods
  • avian communities
  • disturbance
  • ecosystem dynamics
  • fire
  • fire frequency
  • fire management
  • grassland
  • grassland birds
  • grazing
  • nongame birds
  • population density
  • pyric herbivory
  • range management
  • species richness
  • Tanzania
  • threatened and endangered species
  • wildfires
  • wildlife habitat management
Region(s):
  • International
Record Maintained By:
Record Last Modified: June 1, 2018
FRAMES Record Number: 18019
Tall Timbers Record Number: 25917
TTRS Location Status: Not in file
TTRS Call Number: Not in File
TTRS Abstract Status: Okay, Fair use, Reproduced by permission

This bibliographic record was either created or modified by the Tall Timbers Research Station and Land Conservancy and is provided without charge to promote research and education in Fire Ecology. The E.V. Komarek Fire Ecology Database is the intellectual property of the Tall Timbers Research Station and Land Conservancy.

Description

An important question in biodiversity studies is whether disturbances in ecosystems will cause a net loss of species or whether such losses can be compensated by replacement of other species. We use two natural disturbances, fire and grazing, to examine the response of bird and arthropod communities in grasslands of Serengeti, Tanzania. Both burning and grazing by migrant ungulates take place at the end of the rains in June-July. We documented the communities before disturbance, then 1, 4 and 20 weeks after disturbance on three replicate plots and compared them with three undisturbed plots. Birds were recorded by observation, arthropods from pitfall, tray trap and sweepnet samples. We expected that as the grass biomass was reduced by either disturbance, bird communities would change with concomitant change in arthropod food abundance. Alternatively, bird communities would change not with the absolute amount of food but with the greater accessibility of food as the grass structure changed from long to short grass. Results showed first that both bird species richness and abundance increased after both types of disturbance, but burnt sites showed a greater increase than that for grazed sites. Second, there was a change in bird species composition with disturbance. The functionally equivalent athi short-toed lark (Calandrella athensis) was replaced by the red-capped lark (Calandrella cinerea). Third, the abundance of most groups of arthropods was lower on disturbed sites than those on undisturbed sites, and the reduction of arthropod numbers was greatest on burnt sites. These results imply that bird abundance did not occur through an increase in arthropod abundance but rather through a change in the grass structure making food more accessible; and the higher predation could have caused the lower arthropod abundance. In addition, some bird species replaced others thus functionally compensating for their loss.

Online Link(s):
Citation:
Nkwabi, A. K.; Sinclair, Anthony R. E.; Metzger, Kristine L.; Mduma, Simon A. R. 2011. Disturbance, species loss and compensation: wildfire and grazing effects on the avian community and its food supply in the Serengeti Ecosystem, Tanzania. Austral Ecology 36(4):403-412.