Highlights from the 5th International Chough Conference

By Liz Corry

The 5th International Chough Conference was held in Segovia, Spain from the 3rd to 5th October. Held at the Palacio Episcopal building adjoined to Casa de Espiritualidad San Frutos. A very religious affair! And very inclusive events with delegates from Spain, Portugal, Italy, Germany, Switzerland, France and all around the UK. And Jersey!

There were two days of talks focused on red-billed choughs and yellow-billed (Alpine) choughs and a field trip to Hoces del Duratón Natural Park on the final day. Being the chough geeks that we are, the evenings were spent staking out chough roosts in ‘downtown’ Segovia. More on that later.

Question time after each set of talks.

Segovian chouvas

Segovia is a 25 minute train journey north of Madrid and famous for it’s gothic cathedral, roman aqueduct, and Disney-esque Alcázar Palace. It also happens to be home to a large population of red-billed choughs.

A census carried out this year by José González del Barrio and his team recorded 123 choughs roosting in the city. They seem to have a penchant for architectural masterpieces; its not hard to see why. The cathedral is home to half the population with the alcazar and churches accommodating another 30%.

Segovia Cathedral is home to half of the city’s red-billed choughs. Photo by Liz Corry.

It stands to reason that they also have a considerable number of nest sites in Segovia. José’s team recorded 94 nests this year ranging from natural caves to guttering in the cathedral. Bell towers seem to be a particular favourite.

It is not unusual for Spanish choughs to nest in man-made structures, but researchers have noticed an increase in numbers of birds switching from natural mountain caves or crevices to these urban sites.

Just outside of the city (1-3km) there are cereal crops, fallow fields, and grazing cattle and sheep on land they refer to as ‘wasteland’ i.e. can’t grow commercial crops. These provide foraging sites for the choughs (and jackdaws). This is probably why the urban areas are more appealing to raise young rather than up in the mountains where temperatures fall below zero.

However, there is a rather unappealing element to urban living. I’m not referring to the flea-riddled stray cats that prowl the cathedral like a gang of hooded youth. Although cats and rats do predate the birds and eggs. 

Cathedral cats prowl the chough territories but don’t be fooled, its hiding a flick knife somewhere. Photo by Liz Corry

The problem is Segovia’s human inhabitants and their dislike of pigeons. Pigeons roost and nest in the same places as choughs. So when someone puts up a deterrent to stop pigeons pooping on an historic monument, it also stops the choughs. Nine nests failed this year due to human disturbance. The worse cases seeing chicks and/or adults blocked in and starving to death. 

Blocking off building access to combat pigeon problems can be fatal to choughs.

This behaviour is largely due to a lack of awareness over choughs in general. One reason why organisers selected Segovia to host the conference. Our presence in the city (especially on the roost visits) gives the choughs some ‘air time’.  We also had local government officials sit in on the talks. Hopefully public attitudes will change towards choughs. The real challenge will be how to pigeon-proof a structure whilst still giving access to a similar sized species.

City life or country living?

Despite the perils of city living, the choughs have been switching their country cliff-side dwellings for urban development over the last 10-15 year in central Spain. Guillermo Blanco presented data that showed the number of cliff nesting pairs had dropped by 180 pairs over a twenty-eight year period. Switching limestone or clay cliffs for farm buildings and human dwellings.

Jesús Zúñiga had a similar tale to tell in the Sierra Nevada National Park of southern Spain. The chough population has declined by 60% compared to data collected in 1980-1984. This also coincides with an increased use of buildings for roost and nesting.

Choughs in central Spain are switching from cliffs for buildings when it comes to nesting and roosting.

Some choice of nest sites may look familiar to Birds On The Edge readers. Others are a little more suited to the pages of Homes & Gardens magazine.

Kitchen corvids

Affordable homes

Many of the buildings the birds are choosing to nest in are abandoned and nowhere near as intricate as the cathedral and churches of Segovia. Ledges and boxes have been erected by conservationists to support nest construction. They are seeing some amazing results.

As eluded to earlier, predators are more of a problem in these areas. Cats, rats, pine marten and genets. A team from Sociedad de Ciencias Aranzadi have come up with a genius idea – “ugly nests” (patent pending). They have used reclaimed materials such as water containers (too slippery for the mammals to grip) and installed them so they are out of reach from predatory paws.

Installation of artificial nests built with recycled materials.

Wild chough chicks reared in reclaimed artificial nests.

The team were so proud of their ugly nests that we were treated to a demonstration of how easy it is to make one (we had the priest on standby if it all went wrong). We even had an auction with the winning bidder becoming the proud owner of a bespoke ugly nest!

Practical demonstration of how to make a chough nest-box from a water container.

Food availability for choughs

The main reason for the ‘cultural shift’ in Spanish choughs has been the change in agriculture surrounding the limestone cliffs and gorges. Irrigation of the land for maize and fruit growing instead of traditional dry cultivation means a reduction in suitable foraging habitat for the birds.

Places like Segovia on the other hand have livestock grazing within a kilometre of the city walls. This is perfect foraging habitat for choughs (and several hundred jackdaw).

Cattle grazing outside Segovia’s train station provides perfect foraging habitat for choughs and jackdaws.

We know dung is a favourite food source for UK choughs. Gillian Gilbert (RSPB) explained how the Scottish birds particularly like to rummage through dung between July and October in search of invertebrates. In the 1980s, choughs were finding lots of beetles from the Aphodius family. Nowadays, Aphodius numbers have declined and the choughs are more reliant on species of Geotrupes beetles. So what is the problem? Well Geotrupes are soil-boring dung beetles, they drag the dung down into the ground, whereas Aphodius live in the dung. The birds have to work more to probe soil compared to dung which means Geotrupes have less nutritional value.

Eric Bignal feeding choughs in Islay as part of their conservation management.

Food availability (or lack thereof) was a common theme across all countries. In the UK, the Islay choughs began receiving supplemental food eight years ago when researchers noticed a population crash. This extra food, provided by farmers and chough-champions Eric and Sue Bignal, is crucial during the months of September and October. 

In the past few years, several of the Cornish birds have been visiting garden bird feeders to score some free food. This may be more opportunistic than essential for survival, but certainly something researchers should keep an eye on in case things change. 

Yellow-billed (or Alpine) choughs are known to be opportunistic feeders. Mention choughs to anyone who skis in the Alps and they will probably regale tales of over-friendly, black birds hanging around their restaurant table. Alpine choughs have a broader diet then their cousins.  In winter, as temperatures drop they start to forage on juniper berries, seeds, and après-ski leftovers.

Alpine choughs foraging. Spain 2014. Photo by Glyn Young

Cristina Vallino, University of Turin, has undertaken a novel approach to observing the feeding behaviour of these birds around ski resorts. Using the free-access public webcams from ski-resorts in three different Alpine countries she has clocked up 13,704 recordings and analysed flock size, stay time, food intake, vigilance distance and flushing distance. She then combined this with genetic studies of the diet to determine variation in diet. Her concerns for the Alpine chough are the long term effects of eating leftovers. Will this ‘fast food’ be effecting their health?

Frequent flyers

Conservation of European choughs can be a little tricky compared to the UK because the birds can travel long distances. For example, in some years individuals roosting in Segovia may nest in Madrid. Subsequent juvenile dispersal from those nests plays an important role in range expansion. Not just moving within country but between countries too.

Personally speaking, the two most anticipated conference presentations focused on the first use of solar-powered GPS tags on choughs. One on an Alpine chough in Aragon, Spain, the other on red-billed chough in central Spain.

Both studies used transmitters built by a Lithuania company, Ornitrack. The tags transmit data using the 3G mobile network. So as long as you have coverage you can receive data anywhere in the world…roaming charges apply. No joke – just ask the Russians!

Solar-powered GPS tag on a red-billed chough.

The tag is solar-powered which explains the bulky size; the panel needs to be above the feathers in order to charge. The weight of the tag requires harness attachment rather than just gluing on to the body. Juan Manual Pérez-Garcia and his team fitted harnesses to six birds this summer and had some interesting results.

One bird covered a distance of 173km in two days. Another flew 85km on its first flight (in under 3 hrs) then took another 15km journey before settling down for 12 days. Sadly it was then predated by a booted eagle. They know this because an accelerometer fitted in the tag gives an activity pattern. You can detect feeding events, roosting events, and sadly the shaking around and eventual immobility from a predation event. And then the carrying off to the nest to feed the eagle chicks event!

Data from the GPS can provide information on whether the bird is in flight or at rest. Or caught by a booted eagle!

These studies are in their infancy stage. A lot of work is needed looking at the welfare implications of tag attachment. Cost is a small hurdle to overcome considering each tag is about £1,200 plus a data transfer fee. There is definite potential and something we are keen to explore in Jersey.

Future prospects for choughs

The scope of work and tireless dedication evident from everyone in the room (any associates that could not be there in person) is promising for the future of choughs. Whilst classed as least concern, due to their global range, the species appears to be in decline. By sharing data, collaborating on research, and undertaking well-planned translocations or re-introductions we will hopefully halt any further decline. In the process, as several talks showed, this can have a far wider impact for global biodiversity because species restoration works in partnership with habitat restoration.

Helmut Magdefrau put forward their proposal to re-introduce choughs to Slovenia.

And finally

There was far too much to cover in one post. I will end with a photo gallery of chough sightings in Segovia and a couple of videos. All of which may help you plan your 2020 holidays!

La Palma island wildlife recovery centre: choughs often end up at the centre after collisions with power lines or collisions with cats mouths.

.

Leave a Reply