peter hayes
Wednesday 2nd April 2003, 18:22
Here's the BBC weekly feature on garden birds:
Weekly Feature Archive
Most of the British Isles were covered in primeval woodland 6,000 to
8,500 years ago. This was cleared by our ancestors in Neolithic times
(4,000 to 6,500 years ago), who converted the forest to farmland, but
even by the early Iron Age (2,500 years ago) about half of England was
probably still clothed in untouched native forest, or wildwood. Since
that time a total transformation has taken place. Habitats have changed
beyond recognition and a new one of sorts, suburbia, has appeared.
Suburbia is where most of us live. It is where our gardens are and it
is the closest point of contact we have with birds. It is a potpourri of
different habitats, most of which appear in microcosm – a patch of
trees here, an ornamental hedge there, with lawns and shrubbery
everywhere in between. Some birds thrive in this 'unnatural' setting and
a few species may be more abundant in gardens than in extensive
woodland. For example, dunnocks occur at less that 1 pair per square
kilometre in the New Forest compared to nearly 30 pairs per square
kilometre among farmland and gardens in the midlands of Britain.
Judging by outwards appearance and behaviour, dunnocks are something of
a shrinking violet. Their plumage is attractive but subtle and they have
retiring habits, never venturing too far from cover, hopping around the
ground and still worthy of their former title of hedge sparrow.
Actually, 'dunnock' is a much older name and probably refers to the
birds' overall dun colour, again synonymous with being dingy,
mouse-coloured and drab. Hold it right there. The dunnock is a pioneer
species, invading a wide variety of scrub. As a result, it is claimed to
be the second commonest bird in farmed English countryside, being
outnumbered only by the blackbird.
One reason for the species' success is down to sex. To be more precise,
a variable mating system. Sexes are similar so it is impossible to tell
whether an individual shuffling around the bottom of the garden is male
or female. However, if it is a male he could have a harem of several
wives. Not to be outdone, if it is a female she could have several
husbands. Who said birdlife was humdrum in suburbia?
Males and females have a conflict of interest over which is the best
mating system to maximise reproductive success. Dunnocks specialise in
feeding on tiny invertebrates both as the mainstay in adult diet and
when rearing young. Collecting the food is time-consuming so, in areas
where males outnumber females, she acquires several husbands who help
with rearing the brood. Where females outnumber males, husbands will be
shared – even at the cost of leaving some females to raise a family
single-handed.
Dunnocks, robins and wrens form a backcloth of seemingly resident
garden birds. Wrong again. Many of each are winter visitors. Few are
truly sedentary and immigration is noticeable in coastal areas in late
autumn. Dunnocks arrive from the continent along the North Sea coast in
October and November and move inland for the winter. Robins do likewise,
although movements of both species into gardens may also involve
migration within the British Isles. Ringing has shown that robins from
the lowlands of Scotland migrate across the Irish Sea to winter in
Ireland. Even wrens travel considerable distances both across Britain
and, in spring, through the Northern Isles to destinations unknown.
Backyard migrants come as small as goldcrests. Literally millions of
this tiny bird move west out of Russia and Scandinavia each autumn. Our
mild climate and widespread planting of conifers in gardens suit them to
a tee. Because of their diminutive size and hovering, insect-hunting
habit, they feed constantly. Cold snaps kill many although the demise of
one, snapped up by a toad in a garden pond, made a bizarre change from
the huge number of birds killed by suburban cats.
Feeding birds not only provides absorbing spectator sport but it also
has enticed several new
species into gardens. Siskins are tiny
Scandinavian finches that have colonised upland coniferous plantations
in the British Isles in the last century. Outside the breeding season
their food preference switches to catkin-bearing trees such as alders
and birch. Apart from taking advantage of man's forestry activities,
siskins also discovered garden peanut feeders in 1963 in Surrey. Since
then the habit has caught on nationwide. So much so, that a once rare
winter visitor is nowadays usually seen more frequently in gardens than
in the wider countryside. Ringing testifies to the widespread winter
presence of Scandinavian siskins. The ring from one trapped at a feeder
in Belfast in January was discovered in the nest-box of a Tengmalm's owl
in Finland the following summer.
Arguably the most unusual newcomer to gardens in winter is a species
that epitomises summer – the blackcap. Has it lost its migratory
instinct and become resident, moving out of woods in late summer and
surviving on berries during the winter months? It is easy to assume that
summer and winter presence involves the same individuals. In reality,
the winter birds are migrants from central and eastern Europe. While
they are here between November and March, the summer breeding population
is in the Mediterranean.
The explanation for this novel phenomenon is intriguing. Most blackcaps
breeding in eastern Europe migrate south-east in autumn but, as is true
for many migratory birds, a small minority of juveniles read their
navigational 'map' back to front. Put simply, they travel in the reverse
direction. Well, they got lucky and survived the winter in British
gardens. Over the last 30 years numbers have increased spectacularly.
Having inadvertently learned a new migration route, it seems that a
whole new population of European blackcaps has come into existence that
regards the British Isles as a winter home.
Weekly Feature Archive
Most of the British Isles were covered in primeval woodland 6,000 to
8,500 years ago. This was cleared by our ancestors in Neolithic times
(4,000 to 6,500 years ago), who converted the forest to farmland, but
even by the early Iron Age (2,500 years ago) about half of England was
probably still clothed in untouched native forest, or wildwood. Since
that time a total transformation has taken place. Habitats have changed
beyond recognition and a new one of sorts, suburbia, has appeared.
Suburbia is where most of us live. It is where our gardens are and it
is the closest point of contact we have with birds. It is a potpourri of
different habitats, most of which appear in microcosm – a patch of
trees here, an ornamental hedge there, with lawns and shrubbery
everywhere in between. Some birds thrive in this 'unnatural' setting and
a few species may be more abundant in gardens than in extensive
woodland. For example, dunnocks occur at less that 1 pair per square
kilometre in the New Forest compared to nearly 30 pairs per square
kilometre among farmland and gardens in the midlands of Britain.
Judging by outwards appearance and behaviour, dunnocks are something of
a shrinking violet. Their plumage is attractive but subtle and they have
retiring habits, never venturing too far from cover, hopping around the
ground and still worthy of their former title of hedge sparrow.
Actually, 'dunnock' is a much older name and probably refers to the
birds' overall dun colour, again synonymous with being dingy,
mouse-coloured and drab. Hold it right there. The dunnock is a pioneer
species, invading a wide variety of scrub. As a result, it is claimed to
be the second commonest bird in farmed English countryside, being
outnumbered only by the blackbird.
One reason for the species' success is down to sex. To be more precise,
a variable mating system. Sexes are similar so it is impossible to tell
whether an individual shuffling around the bottom of the garden is male
or female. However, if it is a male he could have a harem of several
wives. Not to be outdone, if it is a female she could have several
husbands. Who said birdlife was humdrum in suburbia?
Males and females have a conflict of interest over which is the best
mating system to maximise reproductive success. Dunnocks specialise in
feeding on tiny invertebrates both as the mainstay in adult diet and
when rearing young. Collecting the food is time-consuming so, in areas
where males outnumber females, she acquires several husbands who help
with rearing the brood. Where females outnumber males, husbands will be
shared – even at the cost of leaving some females to raise a family
single-handed.
Dunnocks, robins and wrens form a backcloth of seemingly resident
garden birds. Wrong again. Many of each are winter visitors. Few are
truly sedentary and immigration is noticeable in coastal areas in late
autumn. Dunnocks arrive from the continent along the North Sea coast in
October and November and move inland for the winter. Robins do likewise,
although movements of both species into gardens may also involve
migration within the British Isles. Ringing has shown that robins from
the lowlands of Scotland migrate across the Irish Sea to winter in
Ireland. Even wrens travel considerable distances both across Britain
and, in spring, through the Northern Isles to destinations unknown.
Backyard migrants come as small as goldcrests. Literally millions of
this tiny bird move west out of Russia and Scandinavia each autumn. Our
mild climate and widespread planting of conifers in gardens suit them to
a tee. Because of their diminutive size and hovering, insect-hunting
habit, they feed constantly. Cold snaps kill many although the demise of
one, snapped up by a toad in a garden pond, made a bizarre change from
the huge number of birds killed by suburban cats.
Feeding birds not only provides absorbing spectator sport but it also
has enticed several new
species into gardens. Siskins are tiny
Scandinavian finches that have colonised upland coniferous plantations
in the British Isles in the last century. Outside the breeding season
their food preference switches to catkin-bearing trees such as alders
and birch. Apart from taking advantage of man's forestry activities,
siskins also discovered garden peanut feeders in 1963 in Surrey. Since
then the habit has caught on nationwide. So much so, that a once rare
winter visitor is nowadays usually seen more frequently in gardens than
in the wider countryside. Ringing testifies to the widespread winter
presence of Scandinavian siskins. The ring from one trapped at a feeder
in Belfast in January was discovered in the nest-box of a Tengmalm's owl
in Finland the following summer.
Arguably the most unusual newcomer to gardens in winter is a species
that epitomises summer – the blackcap. Has it lost its migratory
instinct and become resident, moving out of woods in late summer and
surviving on berries during the winter months? It is easy to assume that
summer and winter presence involves the same individuals. In reality,
the winter birds are migrants from central and eastern Europe. While
they are here between November and March, the summer breeding population
is in the Mediterranean.
The explanation for this novel phenomenon is intriguing. Most blackcaps
breeding in eastern Europe migrate south-east in autumn but, as is true
for many migratory birds, a small minority of juveniles read their
navigational 'map' back to front. Put simply, they travel in the reverse
direction. Well, they got lucky and survived the winter in British
gardens. Over the last 30 years numbers have increased spectacularly.
Having inadvertently learned a new migration route, it seems that a
whole new population of European blackcaps has come into existence that
regards the British Isles as a winter home.