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THE IMPACT OF RAPID LAND REDISTRIBUTION ON AVIAN DIVERSITY AND ABUNDANCE IN ZIMBABWE. N. Chiweshe, M. Dallimer & P.J. Mundy. Why worry about birds?.
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THE IMPACT OF RAPID LAND REDISTRIBUTION ON AVIAN DIVERSITY AND ABUNDANCE IN ZIMBABWE N. Chiweshe, M. Dallimer & P.J. Mundy
Why worry about birds? • Birds have represented the primary focus of a majority of ecological and evolutionaryresearch efforts, providing critical insights into our current understanding of natural processes at the individual, population and community levels. • They are key indicators of the state of the environment
Outline:Debshan Ranch, Insiza District, Matabeleland (90.964 ha)
Landscapes (Debshan Ranch) (76% shrubby grassland =sandy soils)
Debshan Ranch before (2000) Land reform programme • High class cattle ranching and game management; • Stocked 20 000+ cattle/annum with low carrying capacities/unit area • Very low human density (about 200 workers with families staying in compounds spread over six sections of the ranch; • Well controlled veld fires (fire guards maintained annually); • Game hunting done commercially (had the largest herd of Tsessebee Damaliscus lunatus nationally & hundreds of Eland, Wildebeest, Zebra, Sable, Kudu etc)
2. Debshan Ranch before (2000) Land reform programme (ornithologically) • Very important research ground ornithologically; • 30 of Zim’s 44 Specially-protected species recorded here; • At least 50 raptor species recorded here, including owls; • Wabai Hills identified as an IBA because of Cape Griffon roost/breeding site there (100 - 225 birds monitored annually since the 1960s); • Nest sites of 7 raptor & 1 stork species (BSt, PF, LF, BE, Augur Buzzard, Mackinder’s Eagle Owl, Spotted Eagle Owl & CG) around theeastern Wabai Cliff-face • A well managed vulture restaurant (attracting 4 spp – including Ruppell’s Griffon • A haven of Kori Bustards Ardeotis kori (density of 0.41/km or one bird per 2.5 km – Dale & Chiweshe 1991);
Debshan Ranch as is today Due to the country’s land reform programme started in Year 2000,thegovernment acquired 65.800 ha (72.34%) of Debshan Ranch’s 90.964 ha, leaving the remainder (25.164 ha) to Debshan Ranch. Despite this, many more settlers have even partitioned pieces of land (settled themselves) inside the remaining ranch as shown on the map.
Outline of Debshan Ranch (Year 2000 to-date) 1. Debshan Ranch = 25.164 ha 2. Resettled area = 65.800 ha (72.34%) 3. Partitioned land 3. Locations of survey sites: a) Open sites = yellow b) Miombo = dark green c) Acacia = light green
This Research - we did the following: • Bird censuses of different habitats in Debshan and resettled land; • Also recording mammals (seen and signs); • Raptor watches in both Debshan and resettled area; • Opportunistic sightings of raptors and gamebirds; • Visits to Wabai Hills + vulture restaurant to census raptors; • Household questionnaires (structure, livestock #, crops grown, problems – game/birds, & opinion on wildlife conservation
Bird Survey method • 200m/lap Observer; bearing; bird • + 6 laps of 200m each • + distance from transact • to bird measured with • range- finder; • + bearing with a campus ; • + at end of each lap = • vegetation cover (trees • StartFinish & grass) measured; • + mammals & mammal • 100m signs also recorded.
Habitat 2: Miombo Woodland Debshan Ranch Resettled land
Habitat 3: Open Debshan Ranch Resettled area
Results 2:On each site we found (a) Average number of bird species
Results 3: Significance • Overall, there were significantly more species and individual birds on sites on resettled land than on Debshan Ranch. • This difference is due to the larger number of species and individuals recorded on Miombo and Open sites. • There were more species and individuals on Debshan owned Acacia sites, but this difference was not significant.
Results 4: Significance • The differences are statistically significant, but we’ll not display the actual statistical tests to keep the presentation easy to deliver and understand. • This is likely because of the larger number of habitats created by small-scale farming systems when compared to land managed for game and cattle ranching. • Almost certainly there has been a change in the type of species between Debshan and resettled sites. This is a much more time consuming analysis, so I will only do it once we have all the data in from the summer as well.
(a) Other elements of biodiversity:raptors & gamebirds as ‘’special indicator bird species’’ • Opportunistic sightings of raptors & gamebirds showed
(b) Other elements of biodiversity:Presence/absence of game Average total number of game animals seen Average number of species of game animal seen Significantly more species were seen on Debshan land than on resettled land
(c) Other elements of biodiversity:Raptor watches • Timed (30 min) large raptor watch between 10:00hrs and 15:00 hrs; • We carried out 12 altogether, 6 on Debshan, 6 on Resettled land; • Saw raptors on all 6 Debshan Ranch watches, but only one Resettled watch.
(d) Cape Griffon roost cliff-face, Wabai Hills Front view of a Cape Griffon roost (eastern view) Adult Cape Griffon at roost site, wabai hills (March 2012)
Possible problems: Cape Griffons – Wabai Hills • Young Cattle herders enjoy flushing the roosting birds off the cliff with fibre wipes/sjamboks (echoes created flash them off); • Black Eagles have always been disturbing the CG in the past (active territory since 1960s); • Birds foraging further afield due to food shortage (being seen on a regular basis at carcasses at Debshan’sShangani Ranch – 45km NW (C. Edwards - pers comm.);
(e) Other elements of biodiversity:Other breeding bird species monitored - Wabai Hills BSt LF MEO PF Cape Griffon BE Aug B E M W
(g) Other elements of biodiversity:Household questionnaire education, etc
Resettlement side-effects • Suitable wildlife habitats are shrinking fast = biodiv. loss • School-going children often miss classes manning crop fields against problem animals & birds • Increased wildlife poaching and disturbances (high human and dog densities everywhere) • Poor sandy soils = low crop yields & human health resulting in emigration of able-bodied people to cities • Biodiversity loss increasing nationally (44 sp protected)
Perspectives & Recommendations • A bit of a mixed picture so far …. For birds, there are more species and more individuals on resettled land, but game animals have disappeared and large raptors virtually absent. • These are preliminary results. • We have data to do more detailed analyses, which we’ll do after the summer field season. • It is likely that differences between debshan and resettled areas will continue to widen • Would very much like to continue and expand the monitoring work to cover multiple years.
Acknowledgements • Rufford Foundation (small grants) • Debshan Ranch Directorate and management teams • Professor Peter J. Mundy (NUST), M. Dallimer and Dr S. Makhaya (DD– Government Veterinary Technical Services) for their technical ideas and support. • Conference hosts for funding my trip here.