Autumn bird migration news: Garden warblers, flycatchers, chats and waders
The intricately-patterned wryneck © Jill Pakenham/BTO
Easterly winds and drizzle dumped a scattering of migrants along the east coast this week. On a wander down the three-mile long shingle spit of Blakeney Point in Norfolk on Tuesday I was quite surprised to find that the most numerous warbler species was the usually unobtrusive garden warbler, while willow warblers and whitethroats were rather few and far between.
I was also fortunate enough to encounter some scarcer migrants from further east, including a smart greenish warbler (a species which regularly breeds no closer than eastern Scandinavia), a skittish red-backed shrike and a wryneck. The latter is an intricately-patterned and rather peculiar member of the woodpecker family, and late August/early September is a great time to look for them, particularly on the south and east coasts.
Whimbrel are at their peak right now © Ron Marshall/BTO
Late August is also the peak time for several migratory species of wading birds. Just last week, a flock of seven whimbrel flew over me in the unlikely location of a patch of Forestry Commission land in Thetford Forest, highlighting the broad front across which many species migrate. The BirdTrack reporting rate for whimbrel shows a really clear pattern of two peaks of sightings, the first in May and the second right now. One of the best ways to detect this curlew-like wader as it passes overhead is its piping, whistled calls, which you can listen to here.
Question of the week: How do birds find their way? (Part 1)
How migratory birds are able to navigate their way to and from their breeding grounds, often across vast distances, is one of the enduring questions posed by the natural world. We think that there are three key parts this mystery: birds' use of magnetic, celestial and visual cues. Over the next few weeks we'll take each of these in turn and try to explain a bit about how it works.
First up, magnetic cues. There's good experimental evidence that some species of bird are able to detect the Earth's magnetic field. Crystals of an iron-based mineral called magnetite have been discovered in the brains of pigeons, amongst other species, and these are thought to give the bird the ability to sense the polarity of the Earth's magnetic field.
An 'internal compass' is a pretty handy tool to have if you're a migratory bird, allowing you to migrate in roughly the right direction even if you can't see exactly where you're going. It is no good having a compass without a map though and we'll talk about the avian equivalent of a road atlas in a later post.
Have you noticed any birds leaving yet? Anything unsual or suprising? As always, we'd love to hear, so post a comment below.