This year, though local rainfall was minimal (a total of less than a 100 mm for March to July, with only 3 days with just over 10mm), the Tana delta received a very good flood from the abundant rains in the Mount Kenya/Aberdare area. Rains there were so abundant that our favourite hydropower dam operators were forced to release water which allowed the downstream ecosystems and the livelihoods that depend on them to benefit. This has resulted in several tens of thousands of hectares covered by water for over a month we guess and spectacular fish production, grass growth, etc. What this means for the objects of interest of the kenyabirdsnet is rather spectacular.
One evening we were quite impressed by the numbers of Open-bill Storks going over our heads in the central delta and flying westwards to roost. In the evening counting is a bit difficult as they ride thermals and twist and turn and from time to time become neigh invisible, then mix up with other gangs so you just go cross-eyed and the counts go awry. In the early morning however they fly in a more or less straight line and rather low and slow. On July 6th we counted left and right, probably over 250 m on each side from 6:05 am to 6:25 am when there is a continuous flow of the creatures and clocked up 5400. The next day we started at 5:50 am when it starts with a trickle and then gradually builds up adding another 600 before 06:05. Assuming the pattern was the same on both days this would mean 6000 openbill storks over 500 m wide strip. Logically this only represents the birds flying to the southeastern corner of the delta and best a third of the total habitat where one can find these things in substantial numbers during the day. Thus we are looking at anything between 15000 and 25000 Open-bill Storks, definitely in excess of the significant 1% norm of 4000 birds. In between these were also large groups of various Egrets (Cattle, Black, Lesser, Intermediate, Great White), African Spoonbills, Long-tailed cormorants and, in reverse movement Black-crowned Night Herons with in parallel large numbers of Glossy Ibis most probably coming from the Kipini roost and going to feed in the northwestern corner of the Delta. All of this together, just sitting in a single spot, was probably of the order of 50,000 large waterbirds passing to and from their way to work. Then there are still the few thousand of White-faced and Fulvous Whistling Ducks (less than 25% of the former species), a few hundred Comb Ducks and a sprinkling of Spurwing Geese. With all the waders (4 Black-tailed Godwits were seen), kingfishers, fish eagles, etc. we are probably looking at at least 100,000 waterbirds present in the delta.
Conspicuously absent were the Madagascar Pratincoles. This is not amazing as their favourite haunts were all under so much water that these rather short-legged creatures would drown. Also, with the water still flowing very actively insect production was still low but will probably rise spectacularly by August when we expect them to be back in high numbers. A few hundred were seen in the saltworks just north of Malindi.
For decades the “Garsen Heronry”, described in 1956 by North, was a major site for colonial waterbirds in East Africa. With the changes brought about by mainly the establishment of the Tana Delta Irrigation Project and the 5 dams upstream, its original locality ceased to be appropriate and only occasional breeding records emerged from the delta. This year however there is again a full scale breeding colony of an estimated minimum 5000 pairs but probably quite a lot more. One should also take into account that the breeding season of different species is not synchronous with currently most of the smaller species (Common Squacco, Black-crowned Night Heron, Cattle Egret, Little Egret, Glossy Ibis) having quite large young while the African Spoonbill and Sacred Ibis seem to be on eggs. Other species already active in the colony but in small numbers are Black Egret, African Darter, Intermediate Egret and Great White Egret. It is likely that other species may come in later (Purple Heron – one was seen carrying nesting material, Grey Heron, Open-bill Stork?) or have already finished breeding (Long-tailed Cormorant?).
In addition to this a few pairs of Pink-backed Pelicans were found breeding in the Ron Palms that are normally used (a bit later in the season) by the Yellow-billed Storks (some were already on the site and building) and the White-breasted Cormorants.