Saturday, August 23, 2008

Breeding the Red-whiskered Bulbul

Revised and updated to 23 August 2008

Thursday, August 7

As some of you may know, I have been successfully breeding the White-rumped Shama for many years. I have had little interest in breeding other species. However, recently my friends asked me to try to breed the Merbah Jambul (Red-whiskered Bulbul). They were keen on having chicks from a pair they had as the male had the very desirable song of the Yellow-vented Bulbul and also a very good display.

Previous attempts at breeding the pair had been unsuccessful. The pair would abandon their eggs or the eggs would be soft-shelled or infertile. The soft-shelled eggs were a clear indication that the female was not having sufficient calcium while the infertile eggs suggested that the pair were being fed insufficient multi-vitamins and minerals and the male's diet, especially, was lacking in some essential vitamin or other. It was more likely the male as the female had done her part by laying the egg.

To rectify the calcium deficiency, my friends had crushed calcium tablets and mixed it with honey which was then spread on fruit and offered to the pair. This had not worked as the Jambuls would eat the fruit but carefully avoid eating the calcium mixture which would tend to drip off the fruit. Calcium powder mixed with honey and offered in a cup was refused. Froglets and guppies, whose soft bones would have supplied calcium, were also ignored.

One suggestion to get the Jambuls to consume calcium was to mix it with the dry food. I thought this might work but I was more in favour of spreading the calcium on fruit. This way, I would be more able to gauge and control the amount of calcium that the Jambuls consume.

I should mention that calcium should not be offered to birds more than 3 to 4 days a week. The reason is that the female stores in her bones the calcium that she requires to make the eggs. If the birds have calcium offered daily to them, its ready availability will result in the bird’s brain sending a message to the body that it is not necessary to store calcium. The result is that when the female needs to draw on her store of calcium in her bones there may be insufficient calcium and the eggs are soft-shelled. It has been found that offering calcium 3 to 4 times a week will provide adequate calcium for the female's egg-laying requirements.

To overcome the problems I have mentioned I offered liquid calcium instead of powdered calcium as I felt the liquid calcium might be more palatable. I mixed the liquid calcium with a little honey. I then made holes all over the surface of the fruit with a fork before spreading the mixture on it. The holes trapped the calcium mixture so that it was retained on the fruit. The fruit with the liquid calcium mixture was offered to the birds and I was pleased when they readily ate it. I also found that they would eat the fruit with the liquid calcium (without honey) spread on it but they ate less fruit if there was no honey.

I fed calcium to the pair 3 days each week for the past 11 days. For the next 3 days of the week, I spread a multi-vitamin and mineral supplement on the fruit. On the 7th day, fruit was offered without supplements,

Dry food was also offered to the birds daily and they continued to eat it. After 4 pm, mealworms and crickets were offered.

I received the pair 11 days ago and placed them in a spare aviary. I had not been using the aviary for my shamas as the evening sun made the aviary very hot. However, this should not adversely affect the Jambuls which needed more sunlight and would in fact be good for them. In a corner of the aviary, I placed a Penang Pipit plant (I don’t know the English name).

I would have liked to have a tall plant so that I could place the nest higher and camouflage it amongst the leaves but the pot would have been too heavy for the aluminium aviary which was on stands. I had to be satisfied with a potted plant that had a total height of about 2 feet which I placed in a corner of the aviary. I also placed a wire cup, such as those offered to canaries, on the side of the aviary partially hidden by the leaves of the Penang Pipit and about 1 ½ ft. from the aviary floor. For nesting, I offered broom material such as those used by my shamas to build their nests.

When I got the pair, the female was molting on its face and I expected her to go into full molt soon. However, the pair seemed to like their new home and over the next few days the female built and completed the nest.

View of nest from outside aviary:

Inside view of nest:

The 4th egg was laid today. I did not check the nest but could conclude from the absence of the female in the morning over the past few days that she was laying. The female has today commenced to brood and I will know within the next 10 to 14 days if the eggs are fertile.

Now that the female is brooding, I intend to stop the calcium supplement and the insects but continue with the multi-vitamin supplement for 3 days of the week. The pair will get fruit and dry food daily until the chicks are about to hatch when I will offer insects with liquid calcium rubbed on to their bodies.

Update 1 - 9th August 2008

Yesterday morning, before I left for work, I checked and confirmed that the female was on the nest. When I returned home in the late evening, my helper told me that the female had left the nest in the late morning and had remained outside for the rest of the day.

I was not too concerned that the female had not sat for much of the day. My concern was that the heavy rains the night before might have blown onto the nest and she might have decided to abandon it. Otherwise, even if she had not sat for the night I would not be too worried as I knew from breeding shamas that even if the hen remained outside for most of the day and also the entire night, the eggs would still hatch if she eventually returned to the nest.

Below is a quote from “A Guide to Better Hatching” by Janet Stromberg:

Actually, the [embryo] begins to develop before the fertilized egg leaves the warm confines (107 degrees F.] of the hen’s body. About 3 hours after fertilization the newly formed single cell divides and makes two cells. Cell division continues so that by the time the egg is laid there are many cells grouped in a small whitish spot visible on the upper surface of the egg yolk.

When the egg is laid and its temperature drops below 80 degrees F., cell division ceases. Cooling eggs at a temperature of 45-60 degrees F will not kill the embryo, and it will be dormant until placed in an incubator to resume its development. Holding eggs at temperatures above 80 degrees F.[another writer says 70 degrees F] prior to incubation will cause a slow growth which leads to weakening and eventual death of the embryo. If eggs are subjected to temperatures below 40 degrees F prior to incubation the embryo will die.

It will be seen from the above that although the female did not sit on the eggs for most of the day, the eggs would continue to slowly develop. The choice before me yesterday evening was to remove the eggs and place them in the incubator or wait to see if the female would return to the nest. I decide to leave the eggs in the nest.

The female must have returned to the nest in the late evening because, thankfully, when I checked the aviary early this morning, she was on the nest.

Update 2 - morning 11th August 2008

Today is the 4th day that the female is sitting on the nest. The Penang Pipit that I placed in the aviary has died. The leaves have turned brown and shrivelled exposing the nest. I am concerned that the female may find the nest too exposed especially as it is very low and abandon it. When I look into the aviary from a distance I can see the female when she is on the nest and she cannot feel too comfortable that she can also see me. There is nothing I can do at this time since I don't want to disturb the nesting female.

I have not been giving live food since the female commenced sitting. The jambul is mainly a fruit-eater. This morning, I offered about 10 half-grown mealworms to the pair just to vary the diet a little.

I try not to look into the aviary as this could disturb the pair. Even from a distance, I can tell if the female is on the nest. If the female is sitting, I can hear only the voice of the male. If she is out, the pair will hold a conversation.

Update 3 - Thursday 14th August

Today is the 7th day that the female has been sitting on the nest. She usually leaves the nest in the later part of the morning and several times during the day. In the evenings she is always out of the nest until after the sun has set. I only know that she returns to the nest each night because she is on it in the early morning.

Yesterday, I offered a brand of liquid multi-vitamins and minerals that I had not used before. The supplement was syrup based and I expected the birds to take to it. I coated a banana with it. The pair did not like the new brand and they ate only a little of the banana at one end. When the birds like the taste of the fruit, they tend to eat the whole fruit.

If all goes well, I expect the eggs to hatch in 4 or 5 days time but to be safe I will offer live food from this Sunday, 17th August, which will be the 10th day.

Update 4 - 22 August 2008

There was no sign by last Sunday evening of any hatching. However, the female spent more time on the nest as can be expected when the eggs are about to hatch.

From Monday to yesterday, I left home early and returned in the late evening. Each day, my helper at home told me that she had not seen any sign of eggshell or of the adult birds feeding chicks but she did say that the adults seemed to be consuming more crickets and mealworms.

This morning, I peeked into the nest when the female was out. There was only one chick. It seems to be about 4 to 5 days old. It was resting comfortably in the nest which was clean. It would seem that the parents are diligently feeding the chick and removing the excreta.

If all goes well, I will remove the chick for hand-feeding tomorrow or Sunday so that I can be sure that it will be safe. I will then take photos and post them.

Update 5 - Saturday 23rd August 2008

I removed the nest with the chick this morning. The chick's eyes were open. I would guess that it is 6 days old. It must have hatched last Sunday or Monday, i.e. on the 10th or 11th day after the female commenced to brood. It looks fine and is about the size of a shama chick of the same age. The photograph is below:

The parents do not themselves consume or feed froglets and fish to the chick. It was removed from hand-feeding so that these may be fed to ensure that the chick will grow strong.

After the chick was taken out, the nesting material was also removed and the empty cup was placed high in the aviary and dried leaves placed around it to provide some privacy as shown below:

The nest is completely camouflaged from the outside as shown below:

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