Distribution pattern and densities of breeding pairs
Breeding pairs distribution in the lake mostly occurred in clusters
(clumped) in local breeding sites such as Kianjata, Makereka, Kirima and
Fuleni (Figure 4). In other parts of the lake, pairs were randomly
distributed in a linear manner where the marshes breadth was narrow
(100-500 m wide) such as Ziwani/Mairo-Inya and Kanguu.
A total of 123 breeding pairs were mapped during the 2018/2019 breeding
season. A hundred and three (103) of the pairs were in the main lake
while the rest (20) were in the satellite wetlands, most of which are
man-made reservoirs in private land (Figure 4). It is, however,
important to note that only 61% and 80% of the mapped breeding pairs
attempted breeding (where the pair was observed as at least incubating)
in the lake and satellite wetlands respectively. Overall, 64% of the
123 breeding pairs attempted breeding during the season in
consideration.
Dividing the lake into 3 sections each c.10 km long, the highest number
of breeding pairs were in the middle section (52) followed by the
southern section (32) while 19 were in the north. The average density of
breeding pairs in the lake’s marshes was 6.50±0.84 (SE)
pairs/km2. The highest density was recorded in the
middle section breeding sites at 7.14±1.64
pairs/km2closely followed by the southern section at
7.10±1.10 pairs/km2 while the lowest density was in
the northern section at 4.76±1.28 pairs/km2.
The mean distance between any two neighbouring breeding pairs was
302.53±17.02 (SE) m, and a minimum and maximum of 47 m and 759 m
respectively. A majority (n =20) of the breeding pairs’ positions
were in the range of 201-280 m (Figure 5). These distances were however
observed to vary in different clusters of nests in the north, middle and
south sections of the Lake, and would be expected to vary in different
breeding seasons as new pairs take up territories and conditions in the
breeding habitat change.