On the 1^st Issy laid a fourth egg and remained sitting on the two dummy eggs and one real egg. This was the last egg of her clutch. During the incubation period the choughs managed to reposition the camera obscuring the view of the nest. On the 21^st it seemed as if the birds were taking insects to the nest, but there were no observations of the parents feeding. Over the next two days their foraging time on the ground increased and there were more trips to the nest.

The keepers checked the nest on the 23^rd by opening the hatch at the side: one chick was seen along with the two dummy eggs and one real egg. The chick was accessioned as B7021 and named ‘chick A’. A photo was taken at the nest and sent to Paradise Park who estimated the chick to be three to four days old.

The keepers continued to give several ‘chick feeds’ each day using a variety of insects including ants and ant larvae. On the 27^th the keeper discovered the dummy eggs, hatched eggshell, and a cracked egg at the front of the aviary and it was assumed the parents had just cleaned out the ‘debris’ from the nest, as some birds do, and continued with the  feeds. However, two days later both birds were out of the nest-box preening first thing and not showing interest in insects. The inner lining of the nest was spotted at the back of the aviary so the keeper went straight to the nest box to check. The nest was empty and a search of the aviary found the decomposing body of chick A at the very back on the ground. The body was submitted for post mortem; however, it was too autolysed for useful examination.

The two eggs placed in the artificial incubator at the end of April were monitored closely through weight loss graphs and egg candling. Initially the eggs were set at 37.6°C and 50% humidity, but the eggs were not losing enough weight so the humidity had to be reduced accordingly. A passerine egg should lose approximately 15% of its initial weight when laid by the time it hatches. It is possible to calculate how much weight an egg should lose each day if the incubation period of the species is known.

On the third day of incubation the eggs were candled and found to be fertile because blood vessels were visible. However, they continued to struggle with weight loss throughout the incubation period. On the 14^th the eggs were candled and placed in an egg heart monitor machine and both confirmed to be dead. A post mortem showed that both eggs had suffered early embryonic death. One egg was noted to have a haemorrhage around the embryo and suspected trauma indicating blood loss as the cause of death.

Arthur and Gwinny continued to show little interest in breeding. They would occasionally move twigs around in the nest-box but spent most of their time away from the nest. Arthur’s bill has healed well and now both upper and lower mandibles are the same length.

Captive breeding at Paradise Park

Paradise Park have parent-reared three chicks this season; two chicks from one nest and a single chick from another. The chicks are due to fledge in June. Another nest has failed this year, probably through naivety of a new pair and heavy rain during incubation.

Display flock at Durrell

Nothing of note has occurred with the display flock this month.

General notes

Both adult chough pairs continue to show an interest in the cameras. Tristan and Issy spend a considerable amount of time attacking their camera and we will look at addressing this next season. We do not have access to software to view back any footage recorded from the camera and this too will also be addressed in time for next season.

At the start of this month both pairs had built substantial nests using wool and horse hair to line the centre. On the 12^th an egg was noticed in Arthur and Gwinny’s nest (SF3). From playing back footage we estimate it was laid around 10:30am. It was quite hard to identify a spherical shape 100% of the time as sometimes the wool covered the egg blurring the image. The female was occasionally sitting on the egg but very restless. Nothing could be seen in Tristan and Issy’s nest (SF2).

Two days later when the keeper entered the aviaries around 11:00 there was a broken eggshell at the front of SF3. More alarmingly there were two broken eggshells at the front of SF2. Playing back the footage it looks like the egg in SF3 accidentally cracked in the nest whilst the female was moving material around. It was cracked around 14:49 on the day we first noticed it.

The day after we found the broken eggs the females were still sporadically sitting on the nests. At 17:55 we noticed an egg in SF3. When the keeper entered the aviary the next morning this egg was cracked on the floor. Playing back footage we saw that Arthur enters the nest at 09:57 pecks at the egg for a few seconds, leaves the nest, returns at 09:59 and removes the egg from the nest. It looks like he was eating the contents but not sure if this was the purpose for removing the egg. Whilst this is happening, the pair next door pecked aggressively at the hatch and vocalised a lot. They have removed nesting material that was touching the bottom edge of the hatch. We inspected the box and found that there is a 3-4mm gap along the bottom of the hatch which might be causing the disturbance. We applied duct tape to block off the light and any draught.

The next day (17^th) Gwinny was sitting more tightly on her nest and at 16:55 we noticed she had another egg. If they were not going to sit tight on this egg we planned to pull it for artificial incubation. However, when we went down at 08:20 the egg was on the floor once again cracked. Viewing the footage it seems the female kicks the egg out at 08:10. SF2 nest is still empty.

Egg-laying stopped after this so in total Arthur and Gwinny (our previous breeding female) produced three eggs. Tristan and Issy produced four eggs. All of which were removed from the nest. 

Nine days later on the 27^th an egg was seen in Tristan and Issy’s nest. This appeared to be the same time-gap between first and second clutches at Paradise Park. However, from viewing footage the egg first appears on the 26^th.

This egg was successfully removed from the nest for artificial incubation and the female was given a plastic dummy egg. The egg was set in the Brinsea Octagon 20 at 37.6°C and 50% humidity. The dummy is a plastic egg we usually use for hottentot teal and had been painted to match natural colouration and patterning using Dulux emulsion paints. Since she had not been sitting on the other egg is was hard to tell if she took to it at first.

The next day, the female was sitting on the dummy egg first thing. A second egg was noticed at 09:57 when she left the nest but she didn’t return. At 13:35 we swapped the egg for a dummy and set it in the Octagon. A third egg was visible 10:10 on the 30^th and by the afternoon there were four eggs on the nest (2 dummies, 2 real). By this point the female had started to sit more often and we decided to leave her with these eggs. She has not laid any more eggs. Predicted hatch dates for the eggs are between 14^th and 19^th of May.

Arthur and Gwinny continued to show little interest in their nest despite keepers adding fresh material. Unfortunately on 30^th the keeper discovered that Arthur had broken the tip of his upper mandible. The break is approximately 2cm from the tip but it is still attached. We do not wish to risk breaking it further in a catch-up nor disturbing the female next door from sitting so he has been left alone. We continue to monitor his condition and assume he can eat the meat/egg mix but might not be able to pick up insects as easily. If he looks like he is becoming weak we will intervene.

Display flock at Durrell

Nothing of note has occurred with the display flock this month.

General notes

Whilst playing back camera footage we have observed a couple behaviours:

• On the 22^nd it looks like Arthur takes a mealworm to Gwinny whilst she is sat on the nest; 
• The male enters the nest at 07:54 on the 28^th and attacks the camera then leaves. He repeats this behaviour at least three times resulting in the camera moving position. The female is on the eggs all during this incident.

Work is continuing on the chough breeding aviaries, although it has slowed down through other commitments and emergencies that have cropped. Cables for the cameras are currently being fitted. The cables will run overhead to the Orang-utan building, as opposed to underground. There are too many service pipes, drains, and electrics under there already! Hopefully the cameras will be online by the first week in March.

Durrell Bird Department Staff have been busy trying to get the neighbouring aviaries set up for the breeding season to avoid disturbing the choughs once they are moved. That work is now complete. The display aviary has had issues with mice in the food-bowl located in the catch-up cage. We blocked off the catch-up cage, so the birds could not access it for two days, whilst we set mouse-traps. We caught one mouse in that time and will reassess in a week if we need to repeat it. The entrance door has been mouse-proofed, but there is still the door leading to the entrance to repair. We have tried blocking holes with wire-mesh but the choughs just see that as enrichment!

In the meantime we have found toad spawn in the display aviary pond. A toad was seen in the pond on the morning of the 28^th with toad spawn, and then a few hours later a male and female toad were seen in amplexus. Not sure if the choughs will see the spawn as another form of enrichment, but it is keeping the staff entertained.

The birds themselves have been fine and there is nothing of great importance to report for this month. Biannual faecal samples were submitted on the 13^th. We are still awaiting the results from the Durrell Vet Department. It was noted that Rd-R (B6978) has an overgrown upper mandible, but it does not appear to be causing any problems. When we catch up the adults next month we will try and catch Red too and trim her beak.

Six members of the National Trust for Jersey staff visited Durrell on the 20^th for a tour of the chough facilities. They were shown the diets, helped feed and put out enrichment, and had a sneak peek at the breeding aviaries.

The breeding pairs seem to be tolerating each other there has not been any aggression this month to warrant removing a pair. On the 22^nd the birds began their ‘breeding diet’, which means mixed corn is removed and finely chopped heart added. This will be kept up until the end of August. 

Building work began on the new chough breeding aviaries. We now have two aviaries in Shep’s Field set up to maximise breeding potential. The nest-boxes have been fitted and are awaiting the installation of a camera to one and alteration to a hatch so we can open it. The cameras will then be wired up so we can view the footage on the network computers. This is likely to require laying underground a cable to the Orang-utan Building kitchen.

There are still a few ‘tweaks’ to do to make the breeding aviaries effective seclusion aviaries and a bit of interior design regarding substrate and enrichment. Otherwise all is on course for moving the birds in March.

The birds in the display aviary are now more confident at coming down to the ground to feed. This is evident by the probing holes in the soil and barkchip. There is still tension between the adult pairs. To help simplify the situation when describing their relationships we have given the pairs names. The metal pair (B6694 ♂ and B6697 ♀) will now be known as Arthur and Gwinny respectively. The others (B6696 ♂ and B6695 ♀) have been named Tristan and Iseult respectively.

The juveniles imported from Paradise Park in 2011 have started to form bonds and like to perch together in pairs. Green (♂) and yellow (♀) have often been seen preening each other. Likewise mauve (♂) and white (♀) will hang-out together. On occasion orange has been pushed out of the group and not allowed to perch next to the others. It will be interesting to see if this behaviour continues.

Ps. A newt has been spotted in display aviary pond!