By Liz Corry

4^th International Workshop on the Conservation of the Red-billed Chough, Portugal

Glyn Young and I attended the 4^th International Workshop on the Conservation of the Red-billed Chough in the second week of October (see earlier announcement here). It was held at the Universidade de Trás-os-Montes e Alto Douro, in Villa Real. The conference was well attended with representatives from Wales, Cornwall, Isle of Man, Spain, Portugal, and of course Jersey. Glyn gave a presentation on the Birds On The Edge project and why the chough is being used as the flagship species. Whist I talked about the reintroduction plans and results to date.

All the talks were fairly balanced between field updates since the last, 2010, conference and post graduate research based around genetics and sex determination. There were no major revelations as most of the work has already been published and every population is suffering the same problems….habitat loss and low genetic diversity.

Welsh chough populations face an extra challenge when it comes to habitat loss. They have to deal with continuing erosion of limestone cliffs. Workers here have used artificial nest-boxes for choughs because of this, but have lost one through continued erosion.

Unfortunately with low population numbers, choughs in the UK have very little genetic diversity and most likely already do or will in future suffer from inbreeding. Across Spain their numbers are in the hundreds and thousands yet they are still on the decline. Choughs from Ireland across to Spain share the same genetic makeup and are, therefore, considered the same race (research presented at conference). This opens up the possibilities for sourcing donor stock for our reintroduction and any possible translocation projects in the UK.

However, the different ‘nationalities’ (of choughs) display cultural differences in nest-site selection, roosting, food choice and dispersal. This needs to be taken into consideration when discussing donor stock.

Choughs on mainland Spain are swapping their natural nest and roost sites in the canyons and cliff tops for manmade structures. The research team were very keen to show a photo of choughs roosting on quarry building roof after they had seen the Jersey presentation. Quarries it seems are not an unusual choice for a chough to make. Palm trees, car parks, and a wardrobe in a disused apartment are definitely not what you would expect if you had only seen Cornish choughs.

Field trip: Douro Valley and the International Douro Natural Park

Portugal has only five locations for choughs, mostly in the north. Their main threat is change in land use and, most recently, the introduction of wind turbines (although their true impact is under question).

Intensive agriculture has removed forest and created a landscape prone to natural fires further destroying habitat.

The workshop delegates were taken around the Douro Valley region, home to vineyards, olive groves, and sweet chestnut (see more here). All of which were traditionally farmed by families but now mass produced by corporates. Of course, as a result, the loss of forest increases the risk of wildfire. As we were driving along we could see at least one hillside ablaze.

I would like to tell you great things about the choughs we saw on the field trip on the last day to visit the birds’ feeding and breeding sites. However, since we spent eight hours on a coach, ended up at the Spanish border (intentionally), and didn’t see a single chough I can’t! If I could use Photoshop I would just to pretend we saw them.

What we saw instead were loads (scientific term) of vultures, falcons, and the odd golden eagle…and Glyn’s ‘lifer’, the azure-winged magpie. In a last ditch attempt our patient hosts took us to a known roost site. Unfortunately the choughs chose a different spot that night!

At least its gives us an excuse to go back! We can’t thank our hosts enough and are proud to join this international chough ‘family’. There are more photos from the workshop and field trip here

Inter-island Environmental Meeting 2013

From Portugal to Guernsey. This year’s inter-island environmental meeting was held in Guernsey at the Société Guernesiase. The theme for this year’s meeting was engaging the community to promote biodiversity and cooperation for action. Glyn Young presented on behalf of BOTE explaining how local volunteers have been involved in habitat management and the chough reintroduction. The talk also highlighted the involvement of Jersey schools and how the children have been engaged.

By Liz Corry

Sorel Choughs

Green and Mauve’s ventures into the quarry came to a temporary close this month after a mysterious turn of events. Ronez Quarry personnel phoned the team to report sightings of the pair in their machinery rooms at the bottom of the quarry. In itself, this was not unusual but, as it was during the day and the workers were testing out equipment, there were concerns for the birds’ safety. From the reports it seemed that the birds were actually quite calm, perched in the roof space watching the workers below. The real concern was raised when Mauve returned to the aviary minus her partner and minus her radio transmitter.

It is not possible to say how she lost the transmitter. In flight it was clear to see she was missing the two central tail feathers that would have been attached to the transmitter and closer examination showed they had come straight out at the base rather than having snapped off. Maybe she got them caught or something tried to grab her by the tail. Other than the absent tail feathers she was in good health and her body weight was fine.

Meanwhile, Green’s signal had not moved from the building. A site visit was arranged in the afternoon thanks to Ronez to see conditions inside the building and to try to locate Green. His signal was loud and clear but he was not visible. With a bit of detective work he was finally located outside the building on the lower bank. Mauve’s signal (from her missing transmitter) could not be picked up in the area or along the coast. A quarry worker reported seeing one of the choughs with missing tail feathers whilst in the building earlier so we assume she lost them in the quarry, and the transmitter has been broken or the signal is being blocked.

When Green finally made an appearance he was looking a little subdued. Maybe confused as to where Mauve had gone and stressed at being by himself. Fortunately for him, Black was close by and excitedly calling for food when we appeared. This caught the attention of Green who flew closer to Black. After lots of frantic displaying/flirting by Black, Green joined her and then joined her in the supplementary feed.

The next day saw both Green and Black appearing for food each time the we called them. Until that is they flew back to the aviary on their own accord at the end of the day. We tried to get them back inside the aviary, but the onset of thunder and lightning spooked the pair off the aviary roof and back to the safety of the quarry.

In the morning, Green and Black were back at their normal spot in the quarry. An all-day motocross event at Ronez Point, however, meant an alternative supplementary feeding site had to be found. Luckily with the team having access to the upper level of the quarry they could go in and approach from a different angle. Green was spooked by the use of the catapult, having never seen it before, and flew off across the quarry. Black followed but for some reason turned back halfway and returned to feed. Green continued to fly over the 4 X 4 race day going on at Sorel below him and on to the aviary.

Green’s return was certainly welcomed by Mauve and the others, but the whole atmosphere seemed a little subdued. From observing him over the afternoon it was clear that he was not himself. His feathers on his front and the skin on his feet were grey and ‘muddy’. Presumably this was a result from being in the quarry buildings where rock dust settles in thick layers.

Not having the ability to ask your ‘patient’ what the problem is makes it difficult to know how to treat. The additional problem is that any manhandling and catching of these choughs will stress them which may lead to negative associations. Much like dogs when they hear the v.e.t. word, we don’t want the choughs fearing the a.v.i.a.r.y.

After a day in the aviary, Green’s feathers were clean but the feet were still grey. At training he was eating with the group when called although he wasn’t as quick to get to the food as the rest. This was put down to stress but with a mind that if things didn’t improve there might be an underlying health issue. Observations on the second day showed that he was not strong when flying and often couldn’t make it from one end of the tunnel to the other without losing height and landing on the netting or the ground.

The decision was made to catch him up and upon weighing it was found that he was a good 30-40g underweight. This explained part of the weakness when flying.

Looking at his feet it was clear that the grey was not washable, it was necrotic skin most likely a result of a chemical burn. He had also suffered a chest wound at some point as there was a large scab forming.

Green was immediately put on a treatment of antibiotics to fight any infection. Medication is injected into insects which the chough will then eat. In order to ensure he would get exactly the right dose he had to be housed separate to the others for the duration of the course. He was locked into one of the sheds and given access to part of the poly-tunnel during the day.

Faecal samples were submitted to Durrell’s lab including a group sample from the females. Although with no recent clinical signs, both samples tested positive for gapeworm. This parasite is not unusual in captive birds and can also be found in the natural environment. However, the situation the Sorel choughs are in will mean their stress levels are raised and are, consequently, more susceptible to the effects of gapeworm. All the choughs immediately started a two week course of ivermectin. Unfortunately this meant catching them up to inject them and repeating it two weeks later. In turn this meant no releases could happen until the medication was finished.

Whilst this was going on Black made a surprising yet welcomed return to the aviary. She came back the day after Green had returned. In an attempt to coax her out of the quarry we had shifted the feeding site further west around the edge of the quarry. By the afternoon she had decided to return to the aviary taking a direct route along the cliff-path. Once again her body weight had changed little from when she first left.

Since re-joining the other four choughs the group dynamics have subtly changed. Without anthropomorphising too much this is no doubt related to Green’s time spent with Black as well as the loss of Orange and White. Immediately upon returning to the aviary Black stayed back from the group eating and preening and doing her own thing. Every now and then Mauve would leave Green’s side, fly at Black chasing her from her perch, then return right back to Green and preen him (a sign of pairing). With Green, now the only male, locked away, the competition for his attention has become a bit of a free-for-all.

A veterinary check-up after Green’s medication ended showed that whilst his feet were healing there was still some way to go. The most damage is around the ends of the digits leading to a small risk of losing one or two claws. A new discovery of a puncture wound on the right hock meant that the vet wanted to extend the antibiotic treatment. From assessing the scab and injury site this wound must too have occurred whilst out and about in the quarry. The next physical check-up for Green will be after the treatment has finished on 1^st November. Until then he will be monitored continuously to watch how much he is eating and if he is in any discomfort.

Choughs at Durrell

This month has seen changes afoot within the breeding pairs. Arthur has taken a fancy to the juvenile female who is now coming of age. This was somewhat predictable since Arthur and Guinevere didn’t progress past nest-building this season and failed to produce a clutch last year. ‘Gwinny’ is now perching and feeding with Tristan the male who we originally paired her with in 2010. The switch to Arthur came about when the two females fought over Tristan in 2012 and Gwinny lost out to Iseult. Keepers will be observing Iseult closely now as the breeding season approaches. Along with Tristan and Arthur there is a single juvenile male in the display aviary with a claim to stake.

George, the hand-reared chough flown over in March to assist with the reintroduction, bid his farewells this month and returned to Paradise Park. With the breeding season approaching he needed to move out of the breeding aviary he was being held in. With no alternative and no possibility of using him at Sorel, Paradise Park were asked if they could take him back. George is quite the character and will be missed by all and no doubt there will be a few holidays booked to Cornwall in the near future!

The Bird Department recently purchased new weighing scales, the same model as used at Sorel. The scales’ design makes it easier for certain species to walk or land on them. Bird staff have started training some of the captive choughs as in this way we can monitor weights and infer general body condition, without having to catch the individual and cause unnecessary stress. George was eager to show off his skills when it came to jumping on the scales. It will require a little more work with novices like Arthur and Gwinny.

Nutritional research on captive diets

Earlier this year, Iona Mucherek-Parramore spent time on the Bird Department collecting data for her MSc in Endangered Species and Conservation. Durrell has developed a close relationship over the years with Nottingham Trent University who send students here for various degree programmes. Iona’s study was looking at the nutrient profile of the chough diets at Durrell and relating it to reproductive parameters.

Choughs in captivity are provided with a breeding diet from January to August and then a general maintenance diet for the rest of the year. Birds require more protein in their diet during egg-production and chick-rearing. We cannot provide the diversity and quantity of insects choughs would need, so finely chopped ox heart is added in January to replicate this.

Iona spent eight days at Durrell collecting food samples and analysing reproductive data. On returning to Nottingham Trent she then had several weeks of lab analysis and the daunting task of dissertation writing. Her final thesis was submitted in October, a copy of which will be kept at Durrell.

The analysis brought to light a few interesting points that need addressing before the next breeding season as they may be influencing egg productivity and survival rates. For example there appears to be no difference in calcium provision between the two diets. Extra calcium is added for the breeding season using grated cuttlefish bone. However, other ingredients are reduced which also contain calcium thereby negating the impact of the cuttlefish bone. Also, the fat content year-round is much higher than one would expect for birds. It should be noted though that there is no published data available for choughs to allow a definitive comparison.

By Liz Corry

Sorel Choughs

With the second release at the end of August seeing Green and Mauve flying off to the quarry, September turned out to be a very busy month. After two days of living around the north edge of the quarry, the pair started to explore the coastline eastwards. The blanket covering of bracken heading off to Bonne Nuit was probably the reason they decided to turn back almost immediately and look for foraging sites around Ronez Point. Potential sites are limited in that area but thanks to their training in the aviary and the continuous monitoring by staff they were able to find food.

Using a moveable target board, placed in clear view and on ground where the choughs can land, the birds were lured down for mealworms. Very quickly the pair remembered that on hearing a whistle their keeper would be bringing food. By the second day of supplementary feeding the tracking sessions had turned into feeding sessions with the birds appearing like clockwork.

For reasons known only to them, the pair decided to travel west in the afternoon four days after leaving the aviary. They arrived back at the aviary in the late afternoon much to the delight of the rest of the group and the team. The chough pair didn’t need much encouragement to go back inside the aviary. On cue with whistle and food they flew through the open hatches and joined the others.

The next morning Liz was able to get weights from all of the choughs landing on the scales. Green and Mauve had lost a bit of weight from being out but nothing alarming. Naturally they would have burned more calories flying around exploring the quarry and food would be limited compared to that available at the aviary. Providing the birds with supplementary insects whilst out, no doubt kept their body weight at an acceptable level.

Thick fog led to a few days delay until the next release. This was more eventful than the last due to couple of factors out of the team’s control…weather and uninvited ‘visitors’. All seven choughs ventured outside this time and settled quite happily on the ground in front of the aviary probing for insects. Before it was time to call them back, their attention had been diverted to a flock of 30 carrion crows heading inland from the cliff path. The choughs took to the air with great intrigue and circled with the crows for a few minutes. Curiosity satisfied, the crows departed with the choughs heading towards Mourier Valley. Liz tried to call them back but by this stage they were no doubt overwhelmed. In panic the group began to split up with a pair heading over to Devil’s Hole and one bird flying inland towards the farm. All this was being hampered by the onset of a really heavy downpour forcing the birds to find shelter.

By sunset three birds (Green, Mauve, and Red) had returned to the aviary. Interestingly these were the only three that had previous experience of having to find a roost outside of the aviary. An example of learning by trial and error maybe? Visibility in low light and rain meant the remaining four could only be located via their radio signals. Two were thought to be in the adjacent fields to the aviary whilst two others were near the dirt bike track.

Upon returning at 06.00 the next day the four were visually located and then followed throughout the day. Very early on Orange, Black, and Blue met up in the quarry. White was also in the quarry but for some reason keeping separate. By the afternoon all four were together foraging around the south side. Unlike the pair that had previously spent time in the quarry these four roosted outside on the rock face.

In light of previous activity, the plan was to keep the three aviary birds locked in acting as call birds and monitor the four outside under the assumption they would return to the aviary. After six days out there was concern that these birds had different intentions. Attempts were made to supplementary feed, but with location and wind conditions they were not very successful. On the evening of the 12^th insects were left out in an area the choughs might naturally forage but had not been seen in before. The team were pleased to see the chough there the next morning so the process was repeated. Unfortunately this week appeared to coincide with the departure of summer. Horizontal winds and rain prevented insects from being thrown into the quarry. This probably also forced the birds to stay in the quarry where they knew they could find shelter.

On the 18^th radio trackers were picking up a stationary signal from Orange away from the other three choughs. Bad weather the day before meant that simple visuals on all four birds were not possible in the afternoon. Only two choughs could be seen on the morning of the 18th. The signal from the third implied it was with them, but with lots of hiding places and tall vegetation seeing the colour rings was near impossible. With no change by the afternoon the radio trackers were obviously concerned and approached the management of Ronez Quarry to request permission to search lower levels. Unbeknown to the team, Ronez were trying to contact them at the same time. Sadly workers down on the floor of the quarry had found a recently dead chough and had brought it back up to the offices to return to Durrell.

To the surprise of the team the body recovered was that of White and not Orange. It seems that the movement of White’s signal in the afternoon was a result of her being driven out of the quarry in a company vehicle. The body was taken straight to Durrell’s Veterinary Department where a full post mortem was carried out. The cause of death was recorded as starvation. Although internal parasites were found, it is thought that these were secondary and not the underlying cause of death.

The tracking team was granted permission to enter the quarry under the supervision of Kirsten du Heaume, Operations Manager. Several attempts were made to isolate the signal. The search was hampered by signal bounce from the granite rock and health and safety concerns which prohibited access to certain levels. Kirsten kindly searched a few areas not usually accessed, but with no success. As frustrating as it is, nothing more could be done. The signal location remained unchanged for a week and with no sighting of a third chough, Orange was disappointingly declared deceased.

Blue and Black in the meantime were flying strongly, avoiding the peregrines, and ironically once again taking supplementary feed the day White was found dead. Using a catapult, the insects could be thrown against the wind and reach levels the team could not. The two female choughs settled into a pattern of flying to the supplementary feeding site when called and appeared to not have any reason to leave the quarry.

The release process was restarted on the 23rd with the three in the aviary. If Green and Mauve did return to the quarry they would hopefully meet up with Blue and Black and lead them back to the aviary. Red, now a single female with the loss of Orange, would presumably fly with them in fear of being left behind.

This time, however, the birds didn’t leave the aviary field. They made several short flights from target sites to perching points along the hedgerow erected by the keeper. Having high places to land near the aviary allowed the birds to feel more secure and take time to assess their surroundings. All three returned on call and were locked in the aviary overnight. The next day was very different. The pair exited the aviary within 53 seconds of the hatches being opened, took to the sky and flew straight back to the quarry. Leaving a rather confused Red behind in the aviary.

As the pair flew over Ronez Point an attempt was made to call them down for supplementary feed. Blue and Black flew up from the quarry and took to the challenge readily. Green and Mauve flew over calling, but then headed away and over to Sorel point. After feeding, Blue and Black headed back into the quarry. However, for reasons only known to a chough, Blue decided to continue flying and minutes later landed on the roof of the aviary. After 18 nights of roosting in the quarry and to the delight of Red, Blue spent the night in the aviary.

At the morning’s weigh-in session, Blue was found to be the same weight as when she first left: once again showing the necessity of supplementary feeding if the birds choose to live in the quarry. As Liz was packing away the scales, Green and Mauve landed on the aviary. Like a well-rehearsed routine, the pair walked back into the aviary where they joined the others.

The next release, on the 26^th, was somewhat more predictable with the exception of the gunshots coming from the fields inland. Each time a shot was fired the birds would fly up from the ground to a perch and/or shelf. At the same time that the decision was made to call the birds back before they got too upset, the pair decided it was time to leave. They circled the aviary a couple of times before heading straight back to the quarry. Despite their calls being audible to onlookers neither Black nor the pair made an attempt to meet up.

With all the choughs in the aviary, Black has to make new alliances beginning with a friendly game of hide and seek. Photo 1 by Liz Corry

By the end of the month Black had settled into her routine of meeting the team for food and roosting on the quarry face. Green and Mauve happily roost in the quarry buildings, but return to the aviary for food. Blue and Red appear nonplussed by the absence of the others and continue as normal in the aviary.

By Liz Corry

Radio transmitters and veterinary health checks

The four remaining birds without transmitters were caught up on the 20^th to have new transmitters attached. In the process the other three were also caught to check there were no issues with their new transmitters.

None of the choughs had completed their moult. However, they are at a very advanced stage and therefore fine for a release. It was noted that a knot was loose on a couple of transmitters that had been fitted last month. This was not deemed a huge concern since they are attached in other places including the transmitter being glued to the feather shaft.

Habitat management

This month the National Trust began treating designated areas of bracken with an herbicide as part of their removal programme. Asulox was applied using a hand sprayer. As a safety precaution all the sheep were temporarily removed from the cliffs and housed in the aviary field for four weeks.

The choughs did not seem to mind having new neighbours. In fact it probably provided a novel form of enrichment. The sheep were moved back out before the end of the month.

Soft release underway

The soft release phase began at the end of August (report). The first day went better than imagined with three birds venturing outside. Albeit on the shelving around the aviary. Green (PG) had the honour of taking the maiden flight onto the roof of the aviary and around the tops of the hedges, but didn’t go far. When it came to calling them back after 30 minutes the whole group flew down to the shed end for the food. Green was faced with the dilemma of how to get through roof netting to reach the food. After a quick brainstorming session he remembered where the hatches were and flew back in.

The second night was similar in that three ventured outside this time being a bit more adventurous. When it came time to call them back the three were on the roof of the shed. Eager to get to food two of them worked out straight away where to go. Red (RD), on the other hand, was completely baffled and spent the next two hours trying to figure out how to get in. Her dilemma was twofold: how to get to the food through netting?; how to get to the food without leaving her partner, Orange (OR), who was locked in the shed? She ended up spending the night on the roof. At 6am when keepers returned she was still perplexed. By 9am she had been coaxed inside by giving the birds in the aviary access to the whole polytunnel. As they flew to the end where the hatches are she followed. After a few minutes of letting her familiarise herself with the shelving the aviary birds were shuffled back and the hatches were opened.

As this is a pilot study Red’s experience has provided an opportunity to learn and improve. Roosting boxes have now been added outside the aviary in case a bird repeats her experience. This might also act as another anchor for keeping the birds close to the aviary and reduce the need to search for roost sites further away.