Nightingales in November (64 page)

Thanks to recent work carried out by Peregrine experts Ed Drewitt and Nick Dixon, the diet of urban Peregrines throughout the year is now known to be far more diverse than just Feral Pigeons. By collecting and identifying the prey remains from Peregrines in the cities of Bristol, Bath and Exeter between 1998 and 2007, they were able to identify an astonishing total of 98 species. Varying in size from the diminutive Goldcrest to the substantial Mallard, this emphasises not only the huge diversity of prey now taken, but also the opportunistic nature of the modern urban Peregrine. In their study Feral Pigeons were still identified as the most important prey species, comprising 42% of all items taken throughout the year, but certainly in November, a massive spike was recorded in the numbers of Common Snipe, Woodcock, Fieldfare and particularly Redwing that were taken. All primarily continental breeding species that visit Britain in large numbers during the winter, these birds are almost certainly being singled out while on passage at night.

Despite Robins eating a diet largely based on insects and arthropods between spring and autumn, vegetable food in
the form of fruits, seeds and nuts will inevitably become an increasingly important component as the temperature drops. During early winter, fruits taken from both gardens and the wild will include currants, apples, blackberries, haws, rose hips, elderberries and Yew berries. Having learnt to also take advantage of any food we put out will undoubtedly boost their chance of survival, but in those years with a harsh winter their mortality may still be extremely high. From studies it seems that it is the length of the cold spell rather than the intensity that seems to cause the Robins most problems. Weighing in at around 15 or 16g in the summer, a fat layer put down before the weather turns cold will see the Robins a decidedly chunkier 22 or 23g during the height of winter, which can then be quickly metabolised to help tide them over any short periods with little or no food. However, an analysis of ringing recoveries during harsh winters has shown that most Robins are usually recovered dead in the second week of a cold spell, doubtless birds with their fuel tanks already having been drained dry after the first seven days.

Either unwilling or unable to move out of their immediate territory, as the temperature begins to plummet, Tawny Owls will need to rely on both an intimate knowledge of their local patch and resourcefulness to see them through the winter. Those Tawny Owls holding territories in more rural locations will undoubtedly rely mostly on Wood Mice and Bank Voles throughout the year, while urban pairs may take a larger proportion of birds. However, if push comes to shove, these adaptable and opportunistic birds will also consider taking more unusual prey. Grey Squirrels, for example, have occasionally been recorded at a variety of locations, Edible Dormice have also been documented being taken by pairs holding territories in the Chilterns and
even the remains of fish have been found in some Tawnies' diets. With a far wider prey spectrum than all the other British owls, it seems that, in essence, if it's edible then the Tawny will eat it!

Unlike our mostly sedentary Blue Tits, which will frequently stay within their home ranges for the duration of the winter, migration amongst continental Blue Tits is a far more commonplace activity, as birds nesting at higher latitudes are forced further south to escape the severe north European winter. In fact the only significant movement of any British-breeding Blue Tits will be from those birds nesting in more northerly or upland sites, which will have little choice other than to accept retreating to more benign locations or adjacent low-lying areas as conditions deteriorate. Being such a popular species for research, with close to four million individuals having been ringed, the huge dataset managed by the BTO indicates that females tend to disperse further afield than males. One possible reason for this differential movement between the sexes may be down to an element of competition, with the larger, more dominant (and frankly unchivalrous) males effectively ousting the females from the best neighborhoods.

Likewise with Kingfishers, any birds which bred at higher altitudes may well have already moved towards the lowlands and coast where new winter territories will then need to be established. Kingfishers have not traditionally been as extensively ringed as many other species, but the scant data available suggest that most northern Kingfishers will still be reluctant to move any more than 15km from their breeding territories. However, with nine Kingfishers initially ringed
in Britain and then subsequently found abroad, there does seem some evidence of a migration south and west, with a few individuals even recorded to have taken advantage of the milder winters experienced in countries such as France or Spain.

Unable to cope with any prolonged cold snap, the option of making a quick bolt for mainland Europe's Atlantic coast as soon as the weather turns unpleasant appears a much more commonly exercised option for the Lapwing than for the Kingfisher. Out of 845 Lapwings ringed in Britain that were subsequently recovered abroad, an astonishing 714 were reported from France, Spain and Portugal. This high total suggests that the warming effect of the Gulf Stream along Europe's western seaboards should offer frost-free feeding, which will more than compensate for the effort and inherent risk of undertaking the journey in the first place.

Late November

With autumn drawing to a close it seems the timing of the Kingfisher's breeding season back in the summer will play a large part in dictating when the adults manage to complete their annual moult. Those birds, for example, that concluded their breeding cycles by mid-August should by now be looking particularly smart as they see their moult reaching completion. However, any individuals still in mid-moult due to a late-fledging brood may be left with little option other than to suspend this energetically demanding process to a time when their food supply improves. With the larger, slower-growing primaries usually being retained,
these feathers will then be the first to be replaced upon recommencement of the moult cycle after the following year's breeding season. This suspension will have the knock-on effect of handicapping some Kingfishers due to the moult of one wing being out of synch with the other and even an unbalanced tail too, all factors which could limit their ability to see out the winter. Any surviving juveniles still going strong by this stage will also have completed a partial moult of their entire body and certainly most, if not all, of their tail feathers. Ringers report some youngsters' moults can even drag on into December in those fledging from particularly late broods, but the all-important flight feathers, which initially emerged just a couple of weeks after hatching, will now not be replaced until after their first breeding season.