by Liz Corry
We welcomed six new choughs into Jersey this August, albeit on the very last day of the month. Paradise Park, Cornwall, successfully bred ten chough chicks at their wildlife sanctuary this year and kindly provided us with two males and four females, all approximately four months old.
Once again Lee Durrell and Colin Stephenson generously offered their services to fly over and collect the new recruits. They were joined by keepers Jess Maxwell and Bea Detnon who provided on-board entertainment (more for the pilots than the choughs) on the hour long flight.
After a short delay waiting for a weather front to pass, the crew touched down at Perranporth Airfield around midday where they were greeted by Ali and Ray Hales patiently waiting with six crated choughs.
There was sadly no time for the team to sample the delights of the Cornish coast, although they did squeeze in a Cornish pasty before heading back for Jersey. Bea and Jess drove the birds to Sorel where they were met by myself and the vet team. Each chough was checked over by the vet and given Jersey leg rings before being released into the aviary.
They will be kept locked in the aviary whilst they undergo a quarantine period. During this time we will collect faecal samples to assess their health, target-train them for feeds, and integrate them with some of our own chicks. The latter is important because when it comes to opening the hatches for the first time we want the new birds to follow the flock. Forming ‘friendships’ with the Durrell chicks prior to release should help with this. Friendship might be too emotive. At the very least they should just copy the Durrell chicks. The four foster chicks have been locked in a separate section of the aviary. After one week, to allow for health screening, the two groups will be mixed.
If the release of these new recruits is successful Jersey’s wild chough population will reach 36 individuals including the wild hatched chicks. By which time we will have released forty individuals over the past three years. We anticipated the need to release thirty to fifty individuals over a five year period in order to have enough birds survive and stay around to start breeding. We have now attained this target and have captive-bred pairs successfully nesting in the wild. It is, therefore, highly likely that 2016 will be the last year of releasing juveniles from Paradise Park.
There is a skew in the sex ratio of the population with only 13 males in the group. We will look to address this next year using chicks bred at Durrell as well as waiting to see the outcome of the wild nests. If they all survive the winter there will potentially be four breeding pairs with another three young pairs attempting to nest.
Update on the July release
We reported last month on the release of six chicks bred at Durrell. They continue to thrive and have shown amazing progress in a relatively short space of time. The two parent-reared chicks continue to follow the adults around occasionally trying their luck begging at Mauve a breeding female. At roost time they leave the flock and return to sleep in the aviary with the four foster chicks. Sometimes leaving it to the very last minute of sunlight to break off the fun.
We originally had concern over the foster chicks as they preferred to stay close to their human foster mums rather than the choughs. Knowing that it was probably related to confidence and age we persevered and encouraged them to join the flock. Operation chough crèche was a success. If the foster chicks flew over to us we would walk them towards the flock and stay with them, breaking up sheep dung and digging in the soil to encourage them to look for insects.
They started to become a bit too expectant in our provisioning of food demanding to be fed every time they spotted us. Apart from being extremely annoying it meant our post-release monitoring was heavily biased. They do not have radio-transmitters fitted at the moment so all our location fixes for the birds are based on visual ID of leg rings rather than the radio signal. We stopped the early morning feed and went into stealth mode observing the group from the other side of the valley.
After a week or so the foster chicks stopped being clingy when out with the flock. They would still fly over to say hi, then turn back straight away to join the flock rather than land on us. At the aviary feeds they were eating alongside the adults rather than waiting their turn.
We have previously used the analogy of the first day at school when it came to moving chicks into the aviary. Releasing chicks into the wild flock is exactly the same. They have only had four weeks of ‘term’ but already look like they will graduate with flying colours.
Keeping the analogy going the ‘kids broke up for half term’ on 30th August when it came time to lock them in before the new birds arrived. The easiest way to do this was to wait until after sunset when they had gone inside the aviary to roost. Sunset was at 19:55 that evening. Some birds had already gone inside by 19:30. The parent-reared two flew in from the quarry at 19:54. There were a few scuffles over who was sleeping where before settling down around 20:00 and the hatches could be closed.
In the morning I was greeted by a few disgruntled chicks at the aviary. Not before being greeted by a flock of twenty five outside the aviary. Puzzling since there should have been twenty four. A quick scan of the leg rings after several re-counts and it was clear X was not inside with the rest of her siblings. Presumably she roosted in one of the outside boxes. A morning of food bribery, opening and closing doors, and patience resulted in the four foster chicks being locked in to one half of the aviary along with one of the parent-reared chicks. He needed his identifying leg ring replaced after it fell off several days earlier. Once we had caught him up and added the ring he was released outside.
Veterinary concerns this month
There were two notable cases this month although nothing out of the ordinary. The wild chicks are now much more independent and can make it through an aviary feed without begging at their parents. Silence at the aviary was soon interrupted by sneezing. Two of the wild chicks, from separate clutches, have started showing signs of a nematode infection. Last year’s wild chick was the same a few months after fledging. Plans are afoot to catch up and treat these two.
Foster chick X turned up at the aviary one morning with a distinct limp only putting weight on her left foot at rest. The motherly instinct to wrap her up in cotton wool and keep locked away for a few days was over-ruled by common sense. The choughs have a tendency to have aches or pains every now and then. Life on the cliffs and quarry, in-fighting over food, and a penchant for bullying gulls/kestrels/buzzards lends itself to the occasional injury. We did of course pledge to monitor her closely and intervene if there was no improvement. Less than 24 hours later she was back to her usual self and incident free ever since.
Questions over X’s physical state changed to concerns over her mental state when she demonstrated the most bizarre, yet endearing, behaviour we have seen to date. Choughs like to cache food to be able to provision in harsher times or prevent others from stealing their prize finds. Quite often we see the choughs take food from the aviary to bury on the grazed land or in the quarry. I’ve watched as a foster chick excavate under the edge of my boot, popped in a rabbit dropping, then covered it up. This month Bea witnessed X walk over to the GPS unit she had left on the ground beside her. X flipped it over with her bill down into a dip in the soil then proceed to bury it. Sabotage or stupidity? Feel free to leave your own thoughts in our comments section.
For an idea of scale here is what the GPS unit looks like when it isn’t buried in the ground…
On 14th August, after three weeks of loyally staying around the release site, chick U disappeared. She was absent from the morning aviary feed and still missing by the evening. Dingle and his partner Red were also missing. It was less surprising that these two were missing given their independence. In fact we welcomed it. Maybe they had gone off to explore new territories, pioneers of the Jersey chough population.
The fact a third bird was missing, who happens to be the most clingy of all the foster chicks, was very alarming. After several hours of searching and a restless nights sleep staff were relieved to count all thirty choughs at Sorel the next morning. And of course all behaving as if nothing unusual had happened.
On a lighter note, we reported last month on how dry conditions had been at Sorel and how that was affecting the wildlife. August was still fairly hot although interspersed with heavy downpours and the odd bout of fog. It was a welcome relief to find dung beetles (Trypocopris spp.), locally known as chough hors d’oeuvres, wandering the cliff paths.
The change in weather fuelled the continued growth of bracken engulfing the cliff paths. Pretty panoramic views from the cliff path benches were still possible providing you stood on the benches. It highlights just how domineering bracken can be in the plant community and how the ground below is smothered. Bracken will start to die back in September to reveal the scenic views Jersey’s coastline has to offer. Only to return in spring if left unmanaged.
Looking out from Sorel towards Sark and Guernsey (on the left).
Jess and Bea had the ultimate view of Sark…