Great news released today about little bitterns breeding at our Ham Wall nature reserve for only the second time in the UK. The photo above is courtesy of local nature reserve volunteer John Crispin. Could this be the start of colonisation?
Although it may only be July, many birds are already on the move, heading south after the breeding season. How and why they do this is still one of the great marvels of the natural world.
All birds move around
– in search of food, space, mates or to escape predators. Most birds
however inhabit relatively small worlds, not straying too far from the
places they hatched.
birds however are great travellers and an estimated 15% of all bird
species are migratory. Migration, in its simplest definition is a
regular seasonal movement over a significant distance. Such journeys
are undertaken either in response to deteriorating local conditions or
to exploit seasonally abundant food supplies in another part of the
world. Brent geese for instance make their way here to escape hard
frosts and snow in the arctic tundra where they nest in summer.
may be north-south, as in the case of swallows, but some birds may move
east-west. Russian hawfinches for instance move to Japan and South East
Asia in winter. In some cases migration is altitudinal, with birds
breeding on high ground moving to lowlands for winter. Both curlews and
to some extent kingfishers, show such movements in the UK.
may involve either the whole population (as with swallows) or only part
of it. The father of modern taxonomy, Carl Linnaeus, in the 18th
century described how, in his native Sweden, male chaffinches stayed in
winter while females went south – hence he gave them the name coelebs meaning ‘bachelor bird’.
mechanisms by which birds undertake these journeys are complex. They
need to be in peak condition and to know when to travel. They also need
a good sense of direction and a means of navigation. There is still a
lot to be discovered about migration, but ornithologists have pieced
much together and it is possible to explain the basics.
there’s the question of timing. For winter migrants, it is
straightforward: conditions worsen in the far north and birds head
south. However, for our summer migrants, (the birds that breed here and
spend their winters further south), it’s not quite so easy to explain
for the simple reason that most of them move south well before
conditions worsen. Swifts for instance head off from mid to late
August. How do they know when to go?
its most basic, it appears birds have a genetically inherited internal
clock. This makes them, quite literally, restless at migration times.
This is known from experimental evidence where blackcaps placed in
cages and deprived of external stimuli were found to start fluttering
their wings and generally behave like they wanted to get out at the
times when the rest of population was on the move. This also coincided
with building up of the necessary fat reserves. Such internal-clocks
may also tell birds when to stop migrating at the other end of the
there is the huge question of navigation. How does an animal with a
relatively small brain manage to make its way from A to B when A and B
are sometimes 8,000 miles apart?
is known that migrants can orientate themselves in the right direction
at the appropriate times of the year. Captive birds, again in the
absence of external stimuli, will hop at the bars of their cages in the
general direction that they need to travel. It is thought that this is
achieved through birds having a good sense of the earth’s magnetic
field, in other words, a built-in compass.
compass however, is not enough. It will point the bird in the right
direction, but it will not give the required detail for pinpoint
navigation. For this some sort mapping is required – and it’s in this
area there is still much debate.
us, it is thought that birds are able to use the position of the sun
and stars as an aid to navigation. However, this has disadvantages in
poor weather conditions. It is also thought that birds can make simple
mental maps of their routes. This idea assumes birds can memorise and
use obvious landmarks such as coastlines, hills and rivers to help
steer them in the right direction.
has also been suggested that sound may contribute. Some birds are
apparently sensitive to low frequency sounds, those created by waves
crashing on shores or the passage of wind over mountain ranges. These
sounds travel over huge distances and may act as beacons. Lastly, and
quite bizarrely, it has also been suggested that smell can play its
part – winds in different direction carry different odours (think of
being by the sea) and these may help point birds in the right direction.
is likely to be a combination of the above factors plus others still to
be discovered, but whatever the answer, the feats are still remarkable.
The return of a swallow next year to the same barn its just about to
leave, after a round trip of 16,000 miles is nothing less than
Talbot Heath lies on the edge of Poole and Bournemouth. It’s one of a number of urban heaths with which the conurbation is blessed, and is home to some rare wildlife. Dartford warblers sing their scratchy songs from the coconut scented gorse while numerous reptiles, such as the small but nonetheless exotic sand lizard, bask in the southern sun. It’s a unique and wonderful wild space enjoyed by those that live nearby. But for how long?
On 9 June Poole Borough councillors resolved to grant a planning application to build 378 homes and 450 student units next to Talbot Heath. This decision left us stunned.
For the past forty years we and other conservationists have worked hard to help people understand that these heaths are rare and precious habitats that deserve our highest levels of protection. This site is so important that it is included under the global Ramsar convention, is designated a Special Protection Area under the EU Birds directive, forms of the Bourne Valley SSSI, protected under UK law.
So how could a decision be made to build a huge housing development next to it? There are well-known major risks attached to building next to heaths, and you need to be sure that the pressure from people, their pets, from fire risk and a myriad of other things won’t have a huge impact on the creatures that live there.
The “appropriate assessment” carried out by the council’s consultants, a legal requirement when protected sites are threatened, begged to differ. In a highly surprising conclusion and despite well documented evidence to the contrary, it found that the development would be okay. With a few measures such as cat proof fences, fire control and a bit of extra open space to lure people away from the Dartford warblers, everything would be fine and we need not worry.
The trouble is, these mitigation measures as they are known are not reliable and we don’t think they are up to the job. Poole Borough should know this too. The Dorset Heathlands Interim Planning Framework is an important agreement that we believed would secure a safe future for places like Talbot Heath. Signed by all the local authorities, it clearly states that for development proposals within 400m of a heath:
"... it will not be possible for a local planning authority undertaking an appropriate assessment of a proposal for residential development to be certain that any adverse effects could be avoided or alleviated."
Now let’s compare this with the actual wording of the appropriate assessment that paved the way for the approval of the planning application:
"Taking into account the proposed mitigation and proposed changes to the scheme it is concluded that the plan will not adversely affect the integrity of the European designations."
The difference is plain to see. And this is why the decision to approve the scheme came as a shock. We really thought that Poole Borough understood the implications of developing land next to heathlands.
But here we are. The application is now approved. So what can be done?
Well, we think this decision needs looking at again. And we sincerely believe this has implications well beyond the boundaries of Poole. If this goes ahead, it could open the floodgates to such developments elsewhere, in places such as the Thames Basin (south west of London) where similar interim agreements are in place with planning authorities.
This simply isn’t a local issue about a few houses. It’s a fundamental challenge to the way we protect our most valuable places. And for this reason we are strongly urging the Secretary of State for Communities and Local Government to hold a full public enquiry to investigate the validity of this decision.
For more information visit our casework information page here