Glad rags

Since I last went to Farmoor, four weeks ago, the bird population has plummeted, because most of the overwintering adult waterbirds have left to return to their breeding grounds. It was bizarre to see the reservoir so empty, with virtually no gulls or ducks, and even Coot numbers down in the low three figures, as opposed to the thousand or more that pass the winter at the site. Still, today's visit gave me what I needed: 11,000 steps, coffee, chocolate tiffin, fresh air, and solitude. 

Because most Cormorants you see sit somewhere on the dividing line between low-key and drab, the first time I ever saw one in breeding plumage I thought it was some kind of weird aberration, and it was only the fact that none of the other people in the hide were talking about it that stopped me from getting overexcited and embarrassing myself. Now that I know better, I always check out Cormorants in the late winter and early spring to see if they're developing the strong facial markings and white thigh patches and crowns that distinguish fully mature birds, but though I've seen a few of these over the past month, none has been as spiffy as the little group on the pontoon at Farmoor today. This may be partly because the individuals I see in the Shire and down at Slimbridge are all from the native subspecies Phalacrocorax carbo carbo, whereas the Oxfordshire birds look more like the European race (P. carbo sinensis), which tend to develop heavier and more extensive white head feathering, and more obvious crown tufts. This individual was made up to the nines - as well as the mottled green and yellow patch on its lower jaw, and the deep orange patch above that, it was sporting a bright blue ring around its eye - but luckily all the other adults in the group had gone with the same vibe, so it didn't look especially outré.

The RSPB estimates the resident UK population of Cormorants at 8,200 pairs, and the wintering population at 62,000 individuals. Some of our breeding birds move down into southern Europe for the winter, but a larger number come here from northern Europe. Traditionally the native 'carbo' subspecies was a coastal breeder, forming colonies on cliffs and coastal rock stacks, whereas the European 'sinensis' tribe, which has bred in eastern England for a number of years, was said to be more likely to form inland breeding colonies. Now though, it seems that this distinction is being lost as the two tribes meet and mix, and while coastal breeding colonies are declining, inland ones are increasing and expanding. Where there are trees growing close to food-rich rivers and lakes, these inland colonies can contain scores of nests - which sometimes leads the birds into conflict with anglers, or people concerned about the Cormorants' faeces killing the trees. Human intervention is the biggest threat to the survival of the Cormorant, which can be legally shot under licence.