10 
Bulletin of the EANHS 28( 1 ) 
much irrigation as possible for their tidaJly flooded rice 
paddies and mango and coconut plantations. The delta 
proper, deprived of fresh water, has, in the last ten years, 
become increasingly silted up. The main result has been 
ideal conditions for the commonest (and least used— it 
is a poor timber wood) of the mangrove species: 
Avicennia marina The Kolota brook itself was. until 
October 1997, choked with young seedlings of this 
species. The delta proper, then, lias been a saline estuary 
for some ten years now. inundated with sea water at 
high spring tides, with mangroves and mud-banks exposed 
at low tides. Minimal fresh water flooded into the system 
during the rains from channels further up the Tana at Oda . 
From October 1997, however, a vast change has 
occurred in the delta, always an incredibly dynamic eco- 
system. Huge amounts of fresh water, resulting from 
the freak weather in Ukambani and North East Kenya, 
not to mention the highlands, all ended up in the delta, 
which has resulted in the usually saline estuary of the 
Shekiko running fresh all the way to the mouth and even 
out to sea! 
Two factors have exacerbated the effect of the 
flooding. Firstly the Tana has been somehow 
“emasculated” since the construction of the hydroelectric 
dams in the headwaters at Kiambere, Masinga, 
Kinderuma and so on. Hence the need for extra water by 
the villagers of Ozi and the blocking of the Shekiko. 
Secondly the main mouth of the river, at Kipini, is 
becoming increasingly silted up. thus backing up the 
river in times (rarely in the last ten years) of flooding. 
The El Nifto floods, beginning in October 1997, 
inundated a huge area of hundreds of square miles from 
the Gamga Rice Scheme at Garsen (completed in 1996) 
north of the river all the way down to the mouth, resulting 
in the evacuation of all villages in the area, including 
Kau, home of several thousand people This vast 
freshwater lake still sits, waist deep, as 1 write (end of 
February. 1998). With no main channel out to Shekiko, 
the farming areas of Ozi are completely under water 
and mango and coconut trees are now beginning to die 
from oxygen and nitrogen starvation. The power stations 
up-stream, to the relieve the pressure on the dam walls, 
have had to open flood gates, adding to the problem. 
The ecological effects of the flooding have been 
spectacular, with huge 
amounts of silt and sand 
washed into the delta 
proper, though, as yet, no 
major break seems to have 
occurred in the river bank. 
With all channels running 
strongly out to the sea for 
the first time in ten years, 
the delta has been scoured 
out, including a major die- 
off of the mangrove A 
marina. 
The most visible sign of 
the change apart form the 
new sandbanks, widened Collared Palm Thrush 
channels and flotsam and by l.a. Depew 
jetsam of flooding, has been a marked increase in the 
crocodile population, which has moved into the ideal 
breeding grounds of the delta to lay eggs on the sand- 
dunes. Vast water-meadows have appeared, even on old 
saline mud-banks, where water lilies (perhaps dormant 
all these years) bloom again. The water fowl population 
is flourishing with jaganas in the water meadows, large 
numbers of pink-backed and great white pelicans feeding 
on the resulting explosion in the fish population. Storks 
(saddle-bill, yellow-billed, woolly-necked and open-bill) 
are abundant, fishing in the flood plains, while egrets 
and herons have not had it so good for a long time. 
In short, the delta is enjoying its first fresh water in 
ten years. Had those who have been trying to develop 
this unique and wonderful area into prawn farms 
succeeded in their plan, they would have lost everything 
in the floods. Maybe it is not such a feasible idea, after 
all. 
Is it too much to hope that the villagers of Ozi will 
break the Kolota brook barrier, thus opening up a seasonal 
supply of fresh water to the delta? It would certainly 
mean that the vast floodplain which now stretches from 
Garsen to Witu to Kipini would drain much quicker and 
normal life could be resumed. 
W.I. Knocker, Tana Delta Ltd., Box 77. Watamu, Kenya 
•Editor’s note: The Tana River delta has been designated 
an Important Bird Area (IBA) and is proposed as a 
RAMSAR site 
COLLARED PALM THRUSH CICHLADUSA 
ARQUATA IN LAKE MANYARA NATIONAL PARK, 
TANZANIA 
On 25 August 1997, at approximately 18: 15 while driving 
from the Hippo fbol towards the main gate, I saw, to my 
surprise, a Collared Palm Thrush Cichlodusa arquata 
apparently feeding on the ground in the middle of track 
The bird was so close that identification could be 
confirmed without binoculars: the pale eye and the 
diagnostic collar surrounding the upper breast could 
