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 12th 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 18th 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 26th, 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.
