niche seperation.

The way different animals make use of it. An oak tree is beautiful, and an oak woodland is an incredibly rich habitat in the United Kingdom. It supports a vast amount of life and the reason for that is the oaks have been growing for longer than any other species. So lots of invertebrate herbivores like caterpillars, bugs and beetles have learned to feed on them. This the food for birds, so that's why its such a rich habitat. But how do they all live in a oak woodland, feeding on the same trees at the same time. This is  something niche separation.They portion themselves so they reduce the amount of competition. They find different ways of feeding in the same place at the same time. How does it work? Lets start at the bottom of the oak tree. The ground beneath the oak tree has plenty of insects and other invertebrate's living on it. This is the food for robins, blackbird, thrushes and even redstarts. Then we have the trunk, this home to some charismatic members of the oak community, the treecreeper and nuthatch. Treecreepers climb up the tree closely examining all of the crevices, into which they put their very fine bill to remove their prey. Nuthatches will go up and down the tree looking for similar things. The nuthatches bill is slightly larger than the treecreeper and they will also eat a little bit of fruit. Then you have the greater spotted woodpecker, if there is any dead wood the greater spotted woodpecker will peck it open on the trunk. The greater spotted woodpecker will even excavate a nesting hole. As we go higher the trunk will separate onto its boughs and branches. You then have a different set of birds living up there. Most notably, members of the tit family. The smaller the bird the further it will go out, away from the main trunk. Turning the leaves over looking for caterpillars, hanging onto little branches. Because of all of this it means that all this can survive on an oak tree at exactly the same time. This is why a walk in an oak woodland during spring is so rewarding.

Are cats a problem to wildlife?

With about nine million cats in the U.K and with some garden birds in decline, should we worry about the impact cats have on our birds. Now millions of years of evolution have led cats to be fairly tuned ambush predators, excellent at catching tiny animals. Years of domestication have done nothing to undo it. But how much effect these hunting skills have might not be as clear as we think. A recent mammal society survey estimated that cats bring in around 55 million dead birds every year. But how significant is that? It sounds like a huge amount, which certainly upsets a lot of people. But to find out if this is an issue this is what the r.s.p.b said. Research into the reason why some urban birds are declining has so far not revealed a link between cat predation and what the populations are doing. British birds have evolved over thousands of years to deal with a wide range of predators ,mammalian predators which include, stoats weasels, foxes, badgers and otters. Birds will also lay lots of eggs to combat these predators, but sadly most will not survive. Evidence is also there to say that cats will take weaker or sick birds that are unlikely to survive their first year. So they don`t think cats have a major impact on bird population. Some scientists though doubt the accuracy of the research being used. The stats say that cats bring in 30% of what they kill, so with 55 million birds being brought home there is roughly 128 million dead birds that we don`t see. Could we be underestimating the number of birds that cats kill. We have rely upon figures derived from other studies, unfortunately those other studies come from non urban habitats and even from other countries, so the reason for using 30% is its the only accurate figure we have to go on. What we need is a new technique that enables us to see what the cats are doing in our gardens. Cat com is being fitted to some cats so we can actually see what our cats get up to. This should give us some more accurate data to go on, showing us the impact cats have in urban areas.

How horseshoe bats and ordinary bats differ.

There are nineteen families of bats throughout the world, comprising nine hundred and fifty different species. Only two of the families are found in Britain, the rhinolophidae, or horseshoe bats, and the vespertilionidae, or ordinary bats. There are two British species of horseshoe bats and sixteen different species of ordinary bats. Many people dislike bats, but they are harrmless and very interesting creatures. They are the only mammals capable of flying long distances, using a modified form of the limbs common to all mammals. Scientists classify bats as the order chiroptera, which means hand-wing. Bats do not walk far and have poorly developed hind limbs. When flying fast and in the dark, bats can still avoid obstacles and track down prey by means of elaborate echo- location systems similar to the radar scanning equipment used by shops and aircraft. Bats normally hunt at night, but if we have lots of heavy rain they be seen in the daytime, which is very dangerous as raptors will predate them. The two British bat families have different echo- location systems. Horseshoe bats emit sound through their nostrils and it is focuse into a narrow beam by a fleshy, cone shaped trumpet on the snout. The bat moves its head from side to side to scan what is ahead of it. Ordinary bats emit sound through the mouth, and have in each ear a fleshy spike known as a tragus, which is part of their sound reception system. All British bats eat insects, and as these are scarce in winter the bats hibernate during the colder months. British bats will have summer and winter roosts, female bats will also have maternity roosts. Many bats make seasonal migrations to hibernating places, and some foreign bats turn up on north sea oil platforms or ships, having been blown of course.