Summer Migrants at Aston Lodge Park

by Dave Emley 

Migration is a wonderful thing.  How do those birds know where to head and when?  But it is not straightforward, for there are three main types of migration:

• True migration, where the entire population moves to a totally different and unconnected area, as we see with the Swallow.
• Partial migration, where most of the population translocate - but not all, as we see with the Chiffchaff, where a number remain to over-winter.
• Then there is altitudinal migration, where a species moves from higher levels to lower altitudes in the winter, before moving back in the spring, as is the case with the Meadow Pipit.  Some species show a mixture of types.
• We can also get weather movements when a species is forced to move to milder climes because of bad weather; such is the case with Pink-footed Geese, moving from the east to west coast, because of freezing conditions.

The end of March/beginning of April is when our summer migrants start to return from far-off wintering areas, so let's have a look at some of the commoner species to be seen here.

Chiffchaff

The real herald of Spring, its repetitive chiff chaff chiff chaff song being readily noticeable.  It is a member of the Leaf Warbler group of birds, that spend their time feeding amongst the canopy, occasionally hovering after insects.  They nest at ground level.  Chiffchaff is very similar to Willow Warbler, but it's song, black-coloured legs, and habitat of bobbing its tail up and down, help to distinguish it.  It often frequents the upper canopy, while the Willow Warbler is generally found lower down.  They winter in southern Europe and North Africa, but some remain here through the winter; often around sewage works, where there are plenty of insects.

Willow Warbler

Very similar to the Chiffchaff, but has flesh-coloured legs and a very melodic song.  Like Chiffchaff, they to spend the time in the canopy, but generally at lower levels.  It also seems to prefer lower scrub, to tall trees, where it searches for insects and their larvae, occasionally hovering.  They are trans-Saharan migrants.

Blackcap

This is a common breeding bird on Aston Lodge Park.  It is a short-distance migrant, but it also occurs in the winter.  However, these wintering birds are breeders from central Europe that choose to winter here.  Most of our breeding birds move to southern Europe and North Africa.  They belong to the Scrub Warblers and they nest in thick scrub, from where they sing, making them frustratingly hard to see!  The males and females are quite different.  Males have a black cap and females are reddish-brown one.  In winter they can visit fat or seeds, but in summer, they feed on berries and insect larvae.

Garden Warbler

Another member of the Scrub Warbler group.  This species is distinctive for not being distinctive - plain pale olive-brown.  It has a beautiful song, like that of a babbling brook (all on one level), going on for some time.  The song is often mistaken for that of Blackcap, but in that species, the song has far more changes in tone.  Garden Warblers favour scrub, copses and woodland edge throughout the UK.  The song is delivered from thick scrub so again, the bird can be difficult to see.  They feed on invertebrates and berries; Blackberries and Elder are particularly liked.  They are trans-Saharan migrants.

Common Whitethroat

Common Whitethroat is identified by its distinctive white throat patch and warm brown wing and back feathers.  Like all Scrub Warblers, it favours deep thick scrub, so the brambles on the Grassy Patch attract a pair most years.  It used to be one of the commonest warblers in the UK, up until the 1960s, when there was a catastrophic drop in the population.  This was attributed to a drought in the Sahel region of Africa, that these birds had to cross.  They have never recovered fully, but the population is much improved.  They often sing from exposed stems - a rather scratchy tune.

Lesser Whitethroat

Like the Common Whitethroat, this too has a white throat, but it is much drabber on the wings and back.  It can be a frustrating bird to see!  The song is a distinctive rattle, but usually delivered from inside a bush.  We get one or two a year around Blackies Lane or alongside the railway line. It too, is a Trans-Saharan migrant.

Sedge Warbler

A bird of reedbeds mainly, but will also nest in scrub.  We get one most years that sings from the brambles on the Grassy Patch, or along the stream behind Leacroft.  They have a quite delightful song, which can include snatches of other species - a real mimic.  The white stripe above the eye and the black line through it are distinctive.

Swallow

This, the archetypal migrant; the one most people associate with the arrival of spring.  They are true travellers, going to winter in South Africa.  They can often be seen hawking insects overhead, while a few pairs nest at the riding stables.  The long tail streamers of this bird are typical of adults, juveniles have much shorter ones.

House Martin

A bird in trouble!  As many of you will know, this is a species closely associated with human habitation, for they build their mud nests under the eaves.  They don't have the tail streamers of Swallows, but they do have a white rump.  Numbers have dropped considerably.  When we came here 25 years ago, there were quite a few nesting on the estate.  Last year I saw hardly any.  There is a lot of research going on to find out why their numbers are dropping.  One possibility is the move to UPVC soffits; the nests will not stick to them.  It is possible to buy artificial nests and they have proved successful.  Like Swallows, they are Trans-Saharan migrants.

Swift

If you have visited the Mediterranean, you will be familiar with the screaming flocks of these birds, as they race through the streets and round the buildings.  We have never had that number in the UK, but we used to have a few pairs in Stone.  Sadly, these seem to have gone.  They have a distinctive crescent shape; quite unlike that of Swallow and House Martin.  They nest in crevices in walls and roofs, but modern housing doesn't have space for them.  It is, however, possible to incorporate Swift nesting bricks in house walls.  They are the most aerial of birds, only coming to land in order to nest, otherwise they eat, sleep and mate on the wing!

Meadow Pipit

This species is not a full-blown migrant like, say, the Swallow.  It breeds in upland areas but, in winter, moves to lower levels, often to the coast.  As it returns to its breeding grounds, it can sometimes be seen, or heard, passing over in the Spring or Autumn.  Occasionally small flocks can drop on to the fields either side of Blackies Lane.  Look out for them.

Other Migrants

While you can reasonably expect to see the migrants above, we occasionally get others that are just passing through.  Among them we have seen Osprey, Honey-buzzard, Green Sandpiper, Black Redstart, Common Redstart, Whinchat, Cuckoo, Curlew and Spotted Flycatcher.  That's the thing about migration; you never know what you are going to see.