Status and preliminary findings on the ecology of the critically-threatened
Taita Thrush Turdus helleri
By Edward Waiyaki12, Daina Samba1 & Luc Lens2
1
2
Department of Ornithology, National Museums of Kenya, PO Box 40658, Nairobi Kenya
Department of Biology, University of Antwerp, Universiteitsplein 1, B-2610, Wilrijk, Belgium
(insert Taita Thrush slide - to introduce species)
(insert Taita Hills landscape slide - to introduce Taita hills + mention of larger
project)
Study forest fragments
FRAGMENT
Chawia (CH)
Ngangao (NG)
Mbololo (MB)
Total
Size (Ha)
50
92
200
342
Quality
LOW
MEDIUM
HIGH
Pop Size
38
250
1059
1,347
Density/ha
1.3
2.7
5.3
Aim of study
Investigate the behavioural response of Taita Thrush to habitat degradation by
focusing on its territorial requirements and, to use this information to recommend
conservation action
Presentation
Home range size and its relation to habitat degradation
Methods:
(will insert map showing relative position of fragments and plots within each
fragment; in detail of one plot show established grid, explain methodology then)
Results
Habitat Quality Analysis
Eigenvectors and component scores for the first two principal components (PC1,
PC2) of the seven habitat quality parameters.
Eigenvectors
CANOPY HEIGHT
CANOPY COVER
NUMBER OF TREES
SHRUB STAND AREA
% LITTER COVER
% HERB COVER
LITTER DEPTH (CM)
PC1
0.08
0.06
0.68*
0.56*
0.90*
-0.85*
0.66*
PC2
0.85*
0.89*
0.21
-0.31
0.27
Cumulative proportion of explained variation
0.42
0.66
-0.33
-0.19
Habitat quality categorisation of the seven study plots
NG High
1
NG Mid
MB Low
0
PC 1
MB High
NG Low
CH Mid
CH Low
-1
-2
-2
-1
0
PC 2
1
Summary of Radio Telemetric Data
Fragment
Chawia
Chawia
Ngangao
Ngangao
Ngangao
Mbololo
Mbololo
Plot
CH-Low
CH-Medium
NG-Low
NG-Medium
NG-High
MB-Low
MB-High
Total
Nos
3
3
3
100%
5.2
1.5
1.4
11
11
9
9
49
80%
0.7
0.6
0.5
3.2
2.2
1.5
1.6
0.5
0.4
0.4
0.4
100 % home range and 80 % Core area size
8
Home range
Core area
7
6
Ha
5
4
3
2
1
0
Habitat Quality
PC 1 against Core area size
2
r2=0.34
p =0.17
PC 1
1
0
-1
-2
0.3
0.4
0.5
0.6
Core area size (Ha)
0.7
0.8
PC 2 against Core area size
2
r2=0.56
p =0.05
PC 2
1
0
-1
-2
0.3
0.4
0.5
0.6
Core area size (Ha)
0.7
0.8
Abundance of leaf litter invertebrates against Core area size
Abundance of leaf litter Invertebrates
4
2=0.56
r2r=0.60
p =0.04
3
2
1
0
0.3
0.4
0.5
0.6
Core area size (Ha)
0.7
0.8
Conclusions
Home Range analysis
- Taita Thrush preffer a high well shaded forest with a high abundance of leaf
litter invertebrates.
-Adapts to decrease in habitat quality by occupying larger home ranges
- They are social and overlap highly especialy in high quality habitat
Future research outcome
-Social organisation
-Movement patterns
-Interactions
Conclusions
Related studies
Fluctuating asymmetry (FA)
Lens et al (1999)
-Individuals and populations from low quality habitat/fragment show high
levels of FA
Sex ratio
Lens L, Galbusera P, Brooks T, Waiyaki E & Schenck T (1998)
-Chawia population has a highly skewed male-biased sex ratio
Genetic variability and gene flow
Galbusera P, Lens L, Schenck T, Waiyaki E & Matthysen E (2000)
- The 3 sub populations have differentiated. Mbololo is more different from
the others
-Genetic bottle neck has occured in Chawia
Recommendations for Conservation
The remaining habitat for the Taita Thrush should be intensively protected
and improved with emphasis on tall closed canopy structure
A complete ban on all levels of logging and other forms of timber utilisation
to ensure high quality habitat
Geneticaly selected individuals (especialy females) should be translocated to
Chawia from Ngangao to boost variability and increase local population
recruitment
Some individuals from Chawia should be translocated to Ngangao to avoid
loss of Chawia specific alleles