April 1998 
9 
A decline in the frequency of years with extensive 
heavy winter sea ice in the Antarctic, first noticeable in 
he 1940s, has been accompanied by a fall in Adelie 
Penguin breeding numbers. In winter, the penguins dive 
io catch krill in cracks in the sea ice overlying places 
a here nutrient-rich bottom water comes to the surface. 
Alien sea ice is reduced, survival of adult and immature 
penguins is poor, probably because suitable feeding sites 
ire too scarce or distant. In summer changing patterns 
of snow deposition and melt are leading to the presence 
pf deep snow on the Adelies’ nest sites. This is reducing 
the breeding success of Adelie penguins when they return 
to the colonies to lay their eggs. Some long-established 
-olonies, where this has been a frequent problems, have 
died out. 
The distribution of rocky shore intertidal 
^vertebrates on the Ffccific coast of North America shows 
changes consistent with the effects of global warming. 
In Monterey Bay, California, southern invertebrate 
species have increased significantly in abundance while 
northern species have declined, causing dramatic changes 
:n the community composition. These changes have 
occurred as sea surface temperatures have gradually 
warmed by 1 °C on average since 1920. 
WHAT DO WE KNOW SO FAR? 
Our current knowledge, including that presented in this 
report, indicates that: 
• Climate change is expected to affect wildlife 
because environmental factors determined by 
climate affect the physiology, survival and 
performance of every species studied in detail. 
These environmental factors include air, water 
and soil temperatures, humidity, soil moisture 
and wind speed. 
• Wildlife will be influenced not only by the direct 
effects of temperature and humidity, but also by 
the indirect effect of changes in their competitors, 
predators, parasites and diseases. The effects of 
climate change on individual species will be 
complex, and therefore even subtle changes may 
cause large changes in plant and animal 
communities. 
• Fossils and preserved remains of lake plankton 
and pollen show that, in the past, species shifted 
their geographic range as the climate changed. 
However, current estimates suggest that some 
species will not be able to move quickly enough 
to respond to the predicted climate change. This 
is especially true of areas where human land use 
has made suitable conditions scarce and 
fragmented. 
• Climate change, particularly if it is rapid, could 
considerably disrupt long-established 
relationships between species. The liming of 
important events in the life cycle of plants and 
animals—such as leafing, flowering, migration, 
emergence from pupae and egg-laying—is 
sensitive to annual fluctuations and long-term 
trends in climate. The timing of events is often 
finely adapted to coincide with life cycle events 
of other species that provide food or shelter. 
• Climate change is already cited as the most likely 
cause of changes in the abundance and distribution 
of a number of plants and animals. In some case 
more investigation is needed to exclude possible 
alternative explanations. Research into many 
other species is also required. However, the 
impact of small recent changes in climate on 
wildlife is already sufficient to trigger coneeir 
about the effects of the large climate changes 
forecast for the next century. 
The world's ecosystems are of immense value to 
humans. Given the lack of our knowledge about 
biodiversity and the complexity of ecological 
relationships it seems probable that their importance is 
even greater than we suppose. Therefore, the disruptive 
effects of climate change on ecosystems may be a serious 
threat to human welfare. 
(The report ‘Climate Change and Wildlife’ is available 
for reference in the EANHS office and library.) 
SHORT NOTES 
EFFECTS OF THE 1997/1998 FLOODING AT 
THE TANA RIVERDELTA 
The Tana Delta is often in the conservation news owing 
to ongoing land tussles between private developers and 
the local people living along the Tana River. And it 
should be. The delta is one of Kenya’s most important 
and, so far, virgin wetlands. Comprising five distinct 
but inter-dependent ecological zones—fresh water 
riverine floodplains, mangrove forest, old dunes 
surrounded by water, sea creeks and oceanic beach—the 
delta is a wonderfully rich habitat * 
Large mammals are still plentiful in the area— 
especially buffalo, topi and waterbuck—although their 
populations are under constant pressure from subsistence 
meat poachers. Primates abound, mainly yellow baboon, 
Sykes’ and vervet monkeys and Garnett’s galago. Many 
species of smaller mammals, civets, genets, mongoose, 
bushbuck, also thrive on the abundant food supply yielded 
by the delta: fruit, insects, molluscs, crustaceans and 
fish. Lion can still be found—even on the beach—while 
hippos are fairly numerous. The delta is a major 
breeding ground for the Tana's fast dwindling population 
of Nile crocodile. 
I run the Tana Delta Camp, an up-market tourist 
resort at the mouth of the Shekiko River, where the 
Tana broke out to the Sea in 1961. Since 1986, the maze 
of mangrove channels has become increasingly saline 
since the blocking of the Kolota brook at the mouth of 
the Thna by Pokomo Villagers from Ozi in need of as 
