Guest blog by Simon Wotton, Conservation Scientist, RSPB Centre for Conservation Science
The Bittern is an elusive bird seen occasionally skulking through reedbeds looking for fish or flying over a reedbed on its broad, rounded, bowed wings. The males make a remarkable booming sound in the spring to attract a mate. This year the Bittern survey has recorded a bumper 150 booming males – an encouraging increase on previous years.
Photo: Bittern by Andy Hay (rspb-images.com)
Bittern have made a come back
Bittern were considered extinct as a breeding species in the UK in the 1870s. Following recolonisation early in the 20th Century, numbers of Bitterns increased to a peak of about 80 booming males in the 1950s, but then fell to fewer than 20 by the 1990s, with similar declines witnessed in many other countries in Western Europe. By 1997, there were only eleven booming male bitterns in the UK; these were mainly within the counties of Norfolk and Suffolk, with a small outlying population at Leighton Moss, in Lancashire.
Figure: Bittern population change from 1900 to present.
There has been an annual survey of booming male bitterns every year since 1990, with an encouraging increase in booming numbers to 140 in 2014 and, so far, just over 150 this year. Major wetland habitat management, habitat restoration and creation are ongoing for this species and annual population monitoring is the main yardstick with which we can measure its success. Some of the best places to see and hear bitterns now are wetlands that were created, from the mid 1990s, for bitterns and other wetland wildlife.
The distinctive booms of territorial males can be heard from as early as January at some sites (often following mild and wet winters) and can continue into June and July. The best time to listen out for booming males from the middle of March to the middle of May. A booming bittern can be very distinctive at close quarters, but beware mistaking a distant boom for a mooing cow or even a distant foghorn!
Often male bitterns give a grunting call before their booming is fully developed, this grunting can be hard to hear unless you are close to the bird and it can sound very unlike the final full booms.
When to hear booming bitterns
The breeding season is about the only time of year when it is possible to positively identify a male bittern, as the bare skin around the eye and base of the bill turns a pale blue in males that are in breeding (ie booming) condition.
It is possible to hear a booming bittern at any time of the day, however, the best times to hear them are in the two hours around dawn and at dusk. The time you are most likely to hear a male is about half an hour before sunrise. There is likely to be much less background (ie traffic) noise before dawn than at dusk. There is little point in going to listen for booming bitterns when it is very windy, but they quite happily boom in the rain.
Thank you to our bittern survey volunteers
A large number of volunteers now help to record booming bitterns at a number of reserves, such as Minsmere, Lakenheath and Ham Wall, including coordinated listens involving a number of surveyors to ensure that the whole site is covered from several different listening points at the same time. It is now only possible to achieve a full national survey each year with help from volunteers, landowners and conservation site staff.
Guest blog by Dr Steffen Oppel, Senior Conservation Scientist, RSPB Centre for Conservation Science. You can read Part 1 of the science expedition to Henderson Island here.
On 22 May 2015, the RSPB expedition team arrived on Henderson (Pitcairn Group, UK Overseas Territory) to better understand the ecology of this remote and rarely visited island.
Monitoring Henderson rail and other landbirds
The team has been on the island for about 3 weeks now, and has completed the first round of bird counts and rat trapping.
The team are monitoring the four endemic landbird species (Henderson fruit-dove, Henderson lorikeet, Henderson rail and Henderson reed-warbler) on Henderson to assess whether populations have changed in the four years since the failed rat eradication attempt.
The landbird counts are very encouraging so far, with far more of the endemic Henderson rail being seen and heard across the island than in 2013. The species declined considerably following the bait drop in 2011, but current data suggest that the population has almost fully recovered.
Photo: Henderson rail by Richard Cuthbert
Ten rails have been caught and are being fed in captivity to examine whether they are equally likely to swallow blue rat bait as they swallowed green rat bait, which was used during the 2011 eradication attempt.
The Murphy's Petrels have started breeding, and the team has deployed 4 GPS loggers on incubating birds to track their movements, but so far none of these birds has left their nests.
Photo: Murphy's petrels by Richard Cuthbert
Rat densities and movement on the island
Henderson’s unique biodiversity is currently under threat due to the presence of introduced Pacific rats. One of the key goals of the 2015 expedition is to get a better understanding of the density and movement ranges of rats on the island. Unfortunately, the rat population has also recovered.
The team has captured >150 individual rats so far, and has recorded some long movements of rats across the island. The longest movement of 330 meters in a single day from one trap to another vastly exceeds previous information obtained by radio-tracking in 2013. Some rats near the camp site have apparently survived since 2013, as the team found rats with ear tags from previous expeditions.
Living on one of the most remote islands on the planet
The last week saw some intense rainfall which flooded the camp and had the whole team digging up drainage ditches, but overall we were all happy to have our water tanks full to the brim and even had enough fresh water to take a cleansing shower!
Over the next few months the team will collect more data on vegetation, landbirds, rats, and seabirds, before being relieved by another crew at the end of August.
The Henderson expedition is funded by The Darwin Initiative and David & Lucile Packard Foundation.
Find out more about our Henderson Island Restoration Programme
Guest blog by Alice Ward-Francis, Globally Threatened Species Recovery Officer, RSPB International Department.
An exciting, newly funded, Darwin project is underway on the Liben Plains, in southern Ethiopia. This innovative project is working to restore the Liben grasslands, through the creation of 1,000ha of grazing reserves. The reserves will be managed by pastoralist communities to provide fodder for cattle, so they can produce milk during the dry season hunger gap. The reserves will be able to support a total of 10,000 pastoralists during this critical time.
Photo: Alice Ward-Francis
The reserves will also lead to restoration of the grassland vegetation and provide crucial habitat for the Critically Endangered Liben lark, a species on the brink of extinction.
Photo: Paul Donald
The project team have just undertaken a project site visit to the Liben Plains, to map out the locations of the grassland reserves and meet with partners and stakeholders to discuss plans and agree priority actions for the following months.
The project is being implemented by the Ethiopian Wildlife Natural History Society, SOS Sahel, BirdLife International, and both Coventry and Manchester Metropolitan Universities, as well as 3 local community groups.
During the visit we had the opportunity to see the beautiful and mesmerising Ethiopian landscape. We travelled through many Ethiopian villages and towns, seeing the varied local cultures and meeting many different people, which was endlessly fascinating. It was also challenging and emotional. A place of extremes, Ethiopia is a country on the move, one of the fastest growing African economies, with huge infrastructure development underway and growing numbers of wealthy people in the cities. This is directly contrasted by some of the rural areas where large families get by on barely any food or water, and in towns, homeless children and the elderly wander the streets in search of some money and food. However, Ethiopia is ultimately a place of great joy, with strong and supportive communities, a culture of sharing, and great love for your friends and family. Nearly every face you see wears a beautiful smile and everyone is always ready to help.
Throughout the visit it becomes clear that everyone shares a dream; the restoration of the Liben grasslands to their former glory. We are all very excited about the next steps on the project, particularly the establishment of the reserves, and ultimately to see long grass waving in the wind and full of life. Check back in a few months to see how the project is going!