Uk Priority Species: Bittern
In the days of yore, bitterns have been called many different things- my particular faves include bog blutter, and mire drumble. Fantastic. These names derive from the bittern’s extremely distinctive mating call, which is known as booming. With a quivering body and through great exhalation, bitterns make a very deep, long and mournful note, which sounds like blowing on the top of an empty milk bottle. It can be heard more than 5 km away! Have a look at the momentous booming bittern on film to see it calling. Historically, folklore surrounding the bittern’s call led to the belief that it was an omen for death, and as the poetic genius of Baldrick once surmised: Boom boom boom boom. Boom boom boom boom. Ultimately, all this ramble of course pre-empts the question; are bittern populations actually booming?
The bitterns many guises The bittern is a flexible fellow and has intricate camouflage techniques. They can compact themselves into puffed up balls with only a bill peeking out (cute) or, at the other extreme, thrust their heads and neck straight out vertically and freeze, holding this position for nearly an hour. They can even do this swimming to look like a reed being pushed by the wind. Astonishingly, there are records of bitterns, which have been found hiding by lying horizontally when storms have flattened reed beds! Sometimes bitterns can appear blueish or even purple, this may be because of the blue-ish skin tone that males seem to take on around their bill during the breeding season or because they use a substance called powder down, which is derived from the breakdown of specialised feathers. This is worked into the plumage during preening - using a serrated, comb-shaped specially adapted claw - to keep the birds free from fish and eel slime. Very clever…maybe a little too clever, if you know what I mean…
Have you ever bitten a bit of a bittern? (sorry)Bitterns have been consumed in a wide variety of households and appeared on tables through from the Middle Ages until the 19th century. In 1465, when the Chancellor of England, George Neville, was invested as Archbishop of York, the extravagant celebration meal included, 400 swans, 2000 geese, 1000 capons and 204 bitterns, which is more than double the current population of bitterns! What a greedy bishop. Speaking of greedy people, Henry the VIII had a liking for the bittern and issued legislation protecting each egg of every bittern! (Although his big belly was probably one of the main drivers for their near extinction).
The rise and fall of the bittern Hunting and habitat loss eventually took its toll on the bittern population, and as the bittern grew rarer, egg collecting and trophy hunting became bigger threats. Bitterns finally became extinct as a breeding bird in the UK in the late 19th century following extensive persecution and wetland drainage. After slowly recolonising from the early 20th century, there was a subsequent decline again to a second near extinction in 1997, when just 11 booming males remained.
Bittern: a wildlife celebrity The disappearance of the bittern from the UK in many ways led to the end of negative public attitudes and connections. Along with the bittern’s resurrection came great celebration and it became a very high profile conservation priority. Extraordinary efforts were and are made by the RSPB, Natural England and other organisations, to re-establish this bird. EU–LIFE Nature have funded two large multi partner projects in the UK in 1996, and then again in 2001 to restore bittern habitat and reverse its decline.
Bedtime for bitternsBreeding bitterns need wetland containing wet reedbeds and open water, with lots of fish and amphibians, which are their main foods. Reedbeds are wetlands, dominated by stands of common reed, they are a dynamic habitat that naturally will gradually dry out and become woodland, bitterns prefer the early wet stages of a reedbed’s life. This habitat has been lost historically by being drained and converted for agriculture, and without the right management, some has dried out and turned to scrub or woodland. It needs ongoing management to prevent it drying out and to control vegetation succession.
Most of our important reedbeds are now under conservation management and drainage and lack of management are now less of a problem than they were. Reedbed is amongst the most important habitats for some specialist birds in the UK, and is home to a number of species that are high priorities for the RSPB, they also benefit many different species, such as watervoles, swallowtail butterflies and otters. RSPB reserves total an astonishing one sixth of the UK's reedbed and support around 30% of the total bittern population!
New threatsSadly, both bitterns and reedbeds are now under threat from a new assailant: climate change. A high proportion of reedbed habitat and thusly the bittern population is near to coastal areas where the potential for flooding from sea-level rise remains high. Over the coming century climate change may cause sea levels to rise by 20-50cm, causing storm surges that may destroy sites where bitterns successfully nest. If reedbeds at bittern breeding sites such as Minsmere, Walberswick and Easton Broad become inundated by seawater, then the population may not recover.
Developing mechanisms for dealing with such issues as climate change is an increasingly difficult challenge for conservationists. Not only is it extremely difficult to predict the timescale and intensity of such impacts, it is something that is essentially outside of our control. Developing mitigation measures for species, which are vulnerable to climate change and its impacts, will be an increasing priority. For bitterns, it is imperative that new wetland sites are created further from the coast, to enable them to breed elsewhere. There has been some progress with finding compensatory habitat and the principles are in place, yet delivery remains slow.
Bitterns retreatTwo sites, Ham Wall and Lakenheath Fen, are part of a strategic move to create reedbeds in sustainable locations away from areas of the coast, which are vulnerable to sea level rise. RSPB Lakenheath Fen has been transformed into reedbed habitat from a former carrot field by flood manipulation and reseeding! Excitingly, in 2010, there has been a significant 10% shift in the distribution of the bittern population towards the new, large inland reedbeds. However, in 2010, 41% of nesting females still remain on sites immediately threatened by saline incursion.
And, most importantly, are there booming numbers of Bitterns? Thanks to an ongoing program of detailed annual monitoring funded by Natural England and carried out by RSPB, we know that bitterns are responding well to the large-scale programme of reedbed management and creation. And, in 2010, there was an increase in the number of booming male Bitterns to 87, up from 82 in 2009, and in the number of sites occupied by booming male Bitterns to 47, up from 43 in 2009. The bittern baby boom has also started, which is crucial not least because baby bitterns are adorable little ginger downy fluff balls with big green feet.
Finally, blog challenge time! Apologies in advance, but I am opening the floor to any of you game enough to have a go at crafting your own bittern joke. I have had one entrant already, given below, which I think is pretty good: ‘What did the scientist, who discovered an Arctic-nesting member of the heron family, decide to call it? …wait for it...’Frost Bittern.’ Excellent. You see, easily pleased me. If you think you can do better, then now’s your chance…
These magnificent eagles are the largest birds of prey in the UK, and are one of the biggest birds of Britain, with a wingspan of over 8 ft! White-tailed eagles build their nests on cliffs along the coast or in trees further inland and stay faithful to the nest, often for many years. They are truly beautiful birds, with amber eyes and are sometimes magically known as the ‘eagle with the sunlit eye’. They excite the imagination; I love to picture them soaring through the awe-inspiring landscapes of western Scotland, with their glinting eyes piercing the horizon.
A tragic loss of our heritageThe white-tailed eagle was persecuted to extinction in the UK during the Victorian era. Before their recent reintroduction, the last native bird was shot in Shetland in 1918. Now confined to Scotland, this magnificent bird once had a much larger range, with reports of the species in 17th century as close to London as Wimbledon common and Epping Forest.
In the beginning…Following small-scale releases in Scotland, the government’s Nature Conservancy Council initiated a programme of releases, which involved bringing 82 young birds from Norway to the island of Rum off the west coast of Scotland between 1975 -85. The RSPB became involved in the late 1970s, and since then, this population has recovered steadily. As birds released on Rum started to wander around western Scotland, the RSPB was given the role of finding, monitoring and protecting newly occupied territories.
The first reintroduced white-tailed eagles bred in 1983, and the first chick fledged in 1985. However, because white-tailed eagles do not start breeding until they are five or six years old, and productivity is low, the increase in the population was slow. With the numbers so low, there was a real risk that chance events could lead to the reintroduced population becoming extinct. To minimise the risk of extinction, a further 58 Norwegian eaglets were released between 1993-98, by Scottish Natural Heritage in Western Ross.
Triumphs!The population in western Scotland is now growing at an estimated 10% per year. It can therefore be considered self-sustaining. This is an amazing triumph for a species that was confirmed extinct nearly 100 years before. A real reason to celebrate!
A project to establish a new population in eastern Scotland, began in 2007 and is due to be completed in 2012. There is still plenty of apparently suitable habitat which is unoccupied by white-tailed eagles, giving good scope for population growth.
Following the reintroductions, in 2009, 46 pairs of eagles successfully fledged a total of 36 chicks.
Persecution of the white-tailed eagleSadly, the reason for the historical extinction still poses a threat today. Persecution. There has long been held the misguided belief that white-tailed eagles pose a significant threat to game management and sheep rearing interests, due to their feeding behaviours. In the past, after the conversion of the highlands to sheep farming, bounties were set for any white-tailed eagles killed. Despite common preconceptions, white-tailed eagles are generalist and opportunistic hunters and scavengers. Carrion is an important part of their diet as well as fish, waterbirds, rabbits and hares. Independent research undertaken by the Food and Environment Research Agency and the Centre for Ecology & Hydrology has shown that many fewer lambs are taken than previously believed and in the vast majority of cases, those that are taken, are sickly, weak or taken as carrion. Unfortunately, there is much misinformation about the ecology of white-tailed eagles and this increases public and stakeholder concerns.
Keeping an eagle eyeBird crime 2009, published in September of this year, reported that at least 6 eagles have died from poisoned baits since reintroduction projects began in the UK. This may seem small, but actually constitutes a large proportion of the population and is particularly problematic for such a long-lived, slow reproducing species.
Protection and surveillance will play an important role in safeguarding nesting birds from illegal disturbance and nest robbing. If we want white-tailed eagles to thrive alongside people as their range expands, through both natural range expansion and further reintroduction projects, it is crucial to communicate the negligible risk they pose to human interests.
Many local communities in western Scotland value and protect the white-tailed eagles. There are of course people who don’t like white-tailed eagles, and have concerns about their impacts on livestock etc. We’re always willing to talk to them. Farmers and land managers have played a huge role in this project, and it is important to acknowledge some of the issues they face in living and working with eagles on their land. On the other hand such projects can have positive effects on the communities in which they take place.
Eye spy eagleOn Mull the eagles have excited the public imagination and a public viewing project has been running for ten years. Most local wildlife tourism businesses say the eagles are the top species people want to see when they visit Mull. The eagles bring £2 million each year to the island economy through spend on goods and services – and it’s sustainable income. The eagles are also bringing significant other benefits to local communities. The provision of dedicated educational materials allows local teachers to use the eagles as a teaching resource. Moreover, a percentage of the payments made by visitors to the viewing hide is passed to the Eagle Fund. And, in the 2009/10, £13,000 from the Mull Eagle Fund was distributed to a diverse range of local community projects, including the repair of a war memorial and a sailing club for training local children.
In the future…It would be wonderful to bring this much misunderstood bird back to it’s rightful home in lowland England. Unfortunately, the current cuts in public spending have forced Natural England to withdraw from plans to do just that. Until money can be found and public misconceptions overcome we can only dream of that sunlit eye scanning the English countryside once again. And maybe make the occasional trip to Mull!
UK Priority Species: Grasshopper warbler
You may well be wondering why I have chosen the rather dull coloured grasshopper warbler for my post this week? It is probably apparent that ‘groppers’ (as they’re sometimes known) are not what you would automatically think of if you wanted an exciting or beautiful looking species. Pouring out some delicate prose about their majestic flight patterns or some inspired poetry to compliment their plummage is fairly difficult. However, these birds have inevitably grabbed my attention because they have some rather intriguing behaviours and they carry a very important message.
Heard but not seen The high reeling song of the grasshopper warbler is the best clue to its presence. However, even when you hear one it can be difficult to locate due to the ventriloquial effect of its singing. To create this effect, groppers sing with their bill wide open, turning their heads from side to side. It is often therefore, almost impossible to place. It could be right next to you or, more likely, it could be a hundred metres away. As would be expected from the name, the groppers distinctive mechanical call, sounds less like a bird and more similar to a grasshopper. It has also been likened to the sound made by fishing reels.
A whopper of a gropper opera (I’m pleased with this one)A grasshopper warblers trilling call is made up of 1400 double notes a minute which in turn can equal 250,000 notes in a single night! A study by Eric Simms into the song showed that the call frequency was often beyond a human ear’s range and could carry up to 1 km on a still night. Grasshopper warblers are best listened for between April and July when they perch and sing from songposts, mostly at dawn and dusk but often through the entire night. So, a late evening visit or a dawn vigil to a good site may lead to a very privilidged experience.
Is it a mouse? Is it a cat? NO! Lucky you it’s a grasshopper warbler!An artful creature is the gropper, skulking in the thickest part of a bush, walking, running, creeping and hopping in an almost mouse-like fashion through dense vegetation, often close to the ground. They are secretive and skulking most of the time and only really make themselves known by singing. Creeping through the foliage, hunting restlessly, the grasshopper warbler feasts mainly on insects, whilst their young are fed on caterpillars.
Roll out the red carpet we’ve got a dramtically declining red listerGrasshopper warbler has declined dramatically in Britain, particularly from the 1960s to the 1980s, even though it appears to be increasing in continental Europe. It is now a Red List species following a population decline of more than 50 per cent over the last 25 years. The British decline may be linked to problems with breeding habitat, and winter survival may also vary, as favoured wintering areas may flourish one year and be dried out the next. Recent declines are likely to be attributable to habitat loss, including wetland drainage, hedgerow destruction and intensification of lowland farming.
A tiny bit of happiness for depressed readers of my blog? Research into the problems faced by the grasshopper warbler is still at too early a stage for us to put specific action into place for the species. We still have limited understanding of the cause of decline. Preliminary research into common habitat features of sites occupied by grasshopper warblers is the first step before we can develop a plan for recovery. However…drum roll please! There has been a slight recovery since 1994. This has occurred without RSPB input but there is still a role for RSPB to play in ecological research and subsequent solution testing to aim to increase and sustain recovery.
Scrub a dub dub, 3 groppers in the…scrub? I was lucky enough to get to talk with Gillian Gilbert, a senior RSPB conservation scientist, about the research she has been doing into grasshopper warbler’s habitat preferences during the breeding season. Her research is in the process of being prepared for publishing and should be completed during the next 6 months.
Research found that vegetation structure plays an important part in habitat preference. Groppers just love dense basal vegetation layers, which is often as a result of dead vegetation, regularly in combination with strong tussocky vegetation. Grasshopper warblers often have had wet habitat associations but they also can do well on rich grassland. Ideally, unmanaged grassland, with a good supply of invertebrates, and of course importantly, song post stages from where they can sing from, will have them creeping around in their dozens. They can also do well in young woodland plantations as long as the trees are less than 2m in height.
The gropper intrigue…These birds have got me intrigued. Imagine a species which colonises habitat which was not intended for such purpose? Habitats which can’t be managed, which are not permanent and are constantly changing! That roams around seeking areas that humans have left or forgotten, which are unlikely to be artificially created? Very few sites are specifically managed or intended for grasshopper warblers, and creating or managing for them on a large scale might be difficult due to the transient nature of the habitat. How then can we conserve them?
What you can do to make a difference in the International Year of Biodiversity!S.O.S. Save our scrub The unmanaged, waste ground habitat favoured by groppers often becomes unsuitable, either through vegetation succession or over-management. It is difficult to say by how much their favoured breeding habitat is declining, but the tendency to tidy up these areas of land may continue to restrict available breeding habitat. Therefore, we have an excellent excuse to be lazy! Do we really need to tidy these areas up? What for? Why not leave it? It would save both time and money. There are a number of different ways you can find out if your lucky enough to be near a grasshopper warbler site. Following these links, you can look at the interactive maps of the National Biodiversity Network, view the data sets from Bird Track, or check out the RSPB’s species target maps, to gain an insight. In the future, please consider groppers when deciding about tidying up such areas. You may think these areas are unsightly but grasshopper warblers don’t. And, in return you may even get to hear a whopper of a gropper opera! (Had to get it in again) Scrubs up well…And finally, I have challenge for all you gropper fans! As you might have noticed, the names given to grasshopper warbler’s favoured habitat type do not exactly inspire thoughts of wildlife or nature or even conservation. Wasteland, scrub, unmanaged or unused land, disturbed ground etc. I challenge you to come up with a name for these crucial gropper areas so that we can banish these negative connotations and celebrate their importance.