Lakenheath Fen - Crane powerhouse

The fact that Lakenheath Fen RSPB reserve was a carrot field some 20 or so years ago is often repeated.  The detail that has gone into the design of the site and the management for key species is less often appreciated.  This is no airy-fairy, lets see how it develops type of reserve, beloved of some sections of the conservation community.  This is a targeted and planned development that now delivers for Bitterns, Cranes, Bearded Tits, Marsh Harriers, Water Voles, Otters and a range of specialised wetland and Breck plants and invertebrates.

This week, I attended the ecological review for the year and undertook the annual audit.  There were a minimum of 5 booming Bitterns, with at least 3 successful nests. We reviewed the results of the fish survey throughout the reserve and discussed the habitat management. The detailed management undertaken for Bitterns that has led to a remarkable recovery in the UK is well known, but perhaps the work for Cranes less so.  Cranes have also had a good year at Lakenheath Fen with three chicks fledged from the 2 nesting pairs.  But this is no chance event, rather the result of considerable effort by site staff.

The case of Cranes is an interesting one.  Recently released figures show a total of 48 pairs in the UK this year:  a combination of 27 pairs of (mainly) wild birds in 4 population centres and 21 pairs of the ongoing re-introduction scheme in Somerset. At least 16 young were reared this year. The population in the Fens is doing well, contributing 7 of these fledged youngsters, whilst the Broads contributed 4 and Somerset just one.

There have been several re-introduction schemes of various species of cranes around the world.  None have been totally successful.  They have suffered from various problems such as imprinting on humans, lack of migratory instinct, poor productivity and the cranes generally failing to think and act like wild cranes, particularly when it comes to predators! The well publicised nesting attempts of some of the released birds where they clearly fail to recognize good nesting habitat or exhibit typical crane behaviour is a good example.  Lets hope these issues can be resolved.

So how has Lakenheath become the UK crane powerhouse? The birds first appeared in 2007.  DNA analysis of feathers suggested a Finnish/Russian origin.  Over 10 years, 23 clutches of eggs have been laid, with 11 chicks fledging: an average of 0.55 young per pair.  The fledging rate was poor at first but is increasing in recent years; the last 5 years average 0.8 and a remarkable 1.5 for the last 2 years.  Detailed study of the Cranes by site staff since they first appeared at Lakenheath, notably by Norman Sills, has led to a good understanding of their requirements.   Habitat management seeks to create ideal conditions for both nesting and chick rearing.  However, it is predation, mainly by Foxes that poses the major threat to the youngsters.  Habitat manipulation can help with this but ultimately some control of Foxes is required.  To ensure success, the latest technology of trail cameras and thermal imagers is used in conjunction with a skilled marksman.

The reedbed management aims to create structural diversity for the benefit of the key species.  Cutting and grazing are the key management tools and also aim to enhance viewing opportunities for visitors.  No airy-fairy stuff this – rather it is determined and targeted conservation effort that brings results.

Photo below - Dartmoor ponies eating reed and typha rhizomes

 

The rejuvenation of Leighton Moss

Leighton Moss wetland rejuvenation from graham white on Vimeo.

Leighton Moss was traditionally the stronghold of the Bittern in north-west England and, along with Minsmere, was one of the sites that provided much research knowledge when the Bittern population was at a very low ebb in the 1990s.   However, whilst Bitterns are now surging upwards elsewhere on the back of this research, they continue to decline at Leighton Moss. Yet the site continues to support one of the best densities of Eels and other fish, the Bittern’s main prey, that we have come across.  So what is going on?  The issue is that Leighton Moss is an old and ‘littered’ reedbed. Recession of the reed margins away from silted pools and ditches is making the fish less available to a foraging bird. The problem of reed recession in old reedbeds is well known.  The formation of toxic by-products by the reed litter under anoxic conditions in a high, stable water regime, reduces reed shoot density and vigour.   Reed re-colonisation into anoxic sediments is known to be poor.  This issue is compounded at Leighton Moss by high grazing pressure from an increasing population of Red Deer and by Greylag Geese.

However, when reedbeds start to die-back due to the ageing processes described above, or grazing (by geese or deer for example), the extent of healthy reed can be increased by lowering water levels to expose mud and allow new plants to germinate and establish.  Periodic drying out can be used to vary the proportions of open water and swamp vegetation and effectively rejuvenate the habitat.  Such a pattern of management has been used in the Oostvaarderplassen in The Netherlands.  A mosaic of reed and open water habitat is maintained by a combination of fluctuating water levels and grazing by Greylag Geese. This results in a periodic expansion and recession of reed.  During high water levels, the geese graze back the margins of the reedbed.  During low water levels, the exposed mud is colonised by reed, other swamp plants and ruderals.  When water levels rise again, the seeds of the ruderals provide food for wildfowl and the new reed shoots form an expanding reedbed.

So in 2014, water levels were lowered on Leighton Moss to reveal acres of gloopy mud, with the aim of drying the site during the summer months for a number of years.  In addition, a small cull of Red Deer began, with the aim of reducing their grazing impact.  Such actions that result in changes to the accepted norm are not always popular, but an appropriate quote for this situation might be: ‘If you want things to stay the same, you have to change them’.

By August 2016, significant changes had taken place.  The gloopy muds had consolidated and vegetation was spreading across it.  Reed was both germinating in the damp mud and spreading out by extending runners from the established clumps.  Early colonizing plants such as Golden Dock and speedwells were abundant, providing a massive boost of seed for wintering wildfowl.  The lowered levels bring other changes: more waders in front of the hides and Spotted Crakes appearing in the reedbeds.  Another year or two of lowered water is probably required before returning to a more normal water regime.  We should then see a boost in many species.  However, whether Bitterns will return to their former glory is uncertain.  The reedbed will be healthier but it is still an old, rather dry reedbed, and as such will support a different, but just as important, range of wildlife.

Below:  the same view, 2014,2015 & 2016

The Albufera of Valencia

A work trip to a conference in Valencia in Spain provided the opportunity to learn about and see the Albufera of Valencia; a shallow lake in excess of 2,000 ha located to the south of the city.   Little more than a metre deep, it is of huge importance for its wildlife, supporting around 90 breeding bird species and up to 50,000 wintering waterfowl.  Around 8,000 years ago, the Albufera was open to the Mediterranean Sea but gradually became cut off by sandbanks.  Originally some 30,000 ha in extent, it slowly reduced in extent through both sedimentation and its margins being progressively claimed for agriculture, principally rice production.

There have been major issues with water quality, notably nutrient enrichment, since the 1980s, mainly as a result of spreading urban development from the city and the surrounding agriculture. The formerly clear waters, full of aquatic waterweeds, have given way to algal dominated turbidity. The population of 1,000 or so pairs of Coot declined to just a few tens of pairs as the vegetation disappeared. As the floating vegetation nesting platforms of Whiskered Terns disappeared, so did the terns.  To try to resolve this problem a partnership of organisations came together to form the LIFE+ Albufera Project, funded by the EU.  Between 2007-2012, three areas of rice fields close to the lake were converted to wetlands designed to enhance water quality.  These 'tancats' were carefully land-formed and then planted with a range of emergent plants such as Phragmites and Typha that will extract the nutrients from the water as it flows through.  Water flows down a series of terraces before being pumped back up into the lake. One of these areas, the Tancat de la Pipa was created in 2008 on the northern side of the lake. Its construction was supported by the Ministry of Agriculture, Food and Environment and is managed by SEO Birdlife and Accio Ecologista Agro.  Early results show that significant improvements have been made.

I was shown around the site by the excellent guys from SEO Birdlife (the Spanish Ornithological Society, notably Pablo Vera, who has undertaken many of the bird studies in recent years.  Despite some declines, the Albufera is still a fantastic place for wildlife.  The bird list is impressive, with many species doing well. For example, latest estimates suggest 60 pairs of Purple Heron, 400 of Squacco Heron, 200 pairs of Glossy Ibis, 50 pairs of Little Bittern, 600 pairs of Gull-billed Tern and 1,000+ pairs of both Common and Sandwich Tern.  Around 40 pairs of Red-crested Pochard, a local priority species, breed annually. There have been re-introductions of both Marbled Teal and Red-knobbed Coot, a nest-building pair of the latter causing great excitement on my visit.

A short video here:  The Albufera of Valencia

Restoring Akrotiri Marsh

Phasouri reedbed (aka Akrotiri marsh) is a highly important wetland in Cyprus both for breeding and passage birds. Whilst the breeding birds include Ferruginous Duck and Little Bittern, birders perhaps best know the site for the range of passage birds, such as herons, waders, crakes, wagtails and pipits, that use the pools on the reed/grassland interface as a feeding resource.  The site is highly popular with birders due to the often very close viewing and the good chance of turning up a rarity.  The marsh also has wider importance for its wildlife, not least for the diversity of plants supported by the fluctuating and frequently brackish conditions.  These include the Lesser Water-plantain and the Marsh Lax-flowered orchid.

However, the number of birds currently using the marsh is way below the peaks of past decades.  A key issue has been the spread of reeds into the grassland area with the resultant loss of the mosaic of open grass and pools.  A project to begin the restoration of the marsh (www.akrotirimarsh.org), funded by the Darwin Initiative, is currently being undertaken by Birdlife Cyprus, the RSPB, the Akrotiri Environmental Education Centre and the Cyprus Sovereign Base (whose land it is situated on).

The first crucial task is to understand why the reeds are spreading. The hydrology of the area is complex, with a history of draining (for mosquito control), of controlling water (probably for grazing purposes) and of recent neglect of management.  Although water levels have generally dropped in recent years, they have also become more static as the drainage ditches have become choked with reeds and the sluices have fallen into disrepair. Water may not get so high in the winter but also may not drain effectively in summer. This has allowed the reed to spread into the grassland with a parallel reduction in grazing by the local community on the remaining grassland.  And this is no ordinary reed; it grows to 5m plus!

So the key to a successful restoration is to gain control of the water by clearing ditches and installing new sluices.  Reeds will need scraping back and new pools created. The other crucial element is to work with the local community to increase the amount of cattle grazing the marshes in order to control reed regrowth.  Currently, grazing animals are tethered but the installation of fencing will allow animals to wander freely into the edge of the reeds. The main restoration work will be underway this coming autumn.

A week working in the field in Cyprus in spring is not the worst job in the world.  Early morning wanders across Akrotiri plain saw arrivals of birds most days; the first day had a sizeable arrival of Ortolan Bunting and Tree Pipits and on the last day Pied and Collared flycatchers were everywhere. Glossy Ibis were arriving in flocks every day. Pallid and Montagu’s Harriers drifted through most days and a couple of Eleonora’s Falcons made an early return.  The marsh itself provided Purple and Squacco Heron, Great Snipe, Little Bittern, Great Reed Warbler, Red-throated Pipit, Black, Grey and Blue-headed Wagtails and Blue-cheeked Bee-eaters. The local specialities of Cyprus Warbler, Cyprus Wheatear and Masked Shrike all performed on cue.

The project also aims to enhance the visitor facilities on site through the provision of hides and paths. The present open access is a free-for-all that benefits just a few, disturbs birds and minimizes the number of people that can enjoy the site.  The aim is to provide new walkways and observation points, enhancing both viewing and photographic opportunities.  Overall, the project aims to restore the diverse habitats of the marsh and to strengthen the relationship between the marsh and the local community.  So make Phasouri reedbed a must visit site on your next trip to Cyprus, enjoy the birds and the facilities, and then enjoy beer and sheftalia in the local Polis Tavern.