Missing species

Many waterways, both natural and man made, traverse England. One of these, the shropshire union canal running from Chester to Ellesmere Port, was visited yesterday. In the built up areas this is the textbook ‘green corridor’. Mallard escort their ducklings between narrowboats whilst the males gather in groups to moult. Moorhens sit on their untidy mat of vegetation which serves as a nest.
In the rural areas, the banks are the haunt of warblers. Five species are breeding here, with both chiffchaff and whitethroat being well through the breeding cycle, many pairs feeding young. Despite the obvious vitality of the bird populations, some birds are missing. Warblers in general are abundant but no willlow warblers are present.The woodland are also devoid of spotted flycatcher. Water meadows and damp pasture are conspicuously missing yellow wagtail. Perhaps a little less obviously, an extensive area of marsh and mixed grazing is missing marsh harrier. It is too easy to think of this as a rare bird, as its British population was at one time reduced to four pairs, but it should be present in this habitat.
As our understanding of the habitat requirement of species grows, our assessment of unexpected absence becomes more robust. Perhaps as well as concentrating on what is present in a habitat, we should pay attention to what is not there. This is more difficult to ascertain, but if we ignore it we run the risk of watching whilst the diversity of our wildlife dwindles. I can only suggest that missing species such as these show that something, somewhere is wrong.

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