HKBWS Vicky

Photo credit: Philip Yip
Taken in Ho Sheung Heung farmland area on 11 Aug.Though Black-collared Starling is a common host of Koel, this is the first time we saw BC Starling raising 3 Koel juveniles in one brood. Is this the "highest record" ever?
相片鳴謝: 葉善行
在8月11日河上鄉農地拍得。雖然經常見到噪鵑幼鳥寄生在黑領椋鳥巢，但這是我們首次見到一巢裏有3隻噪鵑幼鳥這麼多。不知道這是否最高紀錄?

ddavid

The Avifauna gives a record of 3 juvenile Koels in a B-c Starling nest on June 30 1931. It also mentions that "dependent juveniles, singly or in parties of up to three, have been recorded between 11 April and 4 November."

David

HKBWS Vicky

Thank you so much for the information!!! So this is not a new record.

wcaptain

Interest to know whether these 3 Koels are brothers and sisters. Or they are from different parents.

It is supposed that the newly hatched Koel will quickly kick out eggs of their froster parents (whose eggs are smaller). In this case, they may be able to recognize eggs of their species and did not kick out these eggs.

Anyway, thanks for sharing this observation.

ajohn

I think it is only certain species of Cuckoos which eject the eggs from the nest. These include Common Cuckoo, which is the best studied species. One reason is that Common Cuckoo is considerably larger than the host, so needs all the food that the parent can collect.
Other species don't have this size difference. Some species may lay more than one egg in the same nest, and some species are raised with the chicks of the host. Koel is probably one of these species.
I would think it is likely that these three are from the same nest, and they are probably brothers. It is interesting that it appears to be three males.

ddavid

N. B. Davies (Cuckoos, Cowbirds and Other Cheats page 72) notes that "Asian Koels parasitize crows, and the young parasite is raised alongside the crow host young." In comparison, the Australian Koel (often regarded as a subspecies of Asian Koel) "parasitizes smaller host species, and the young koel ejects the host eggs and so is raised alone."

The Asian Koel may lay more than one egg in a host nest; the Australian Koel lays a single egg only.

I don't know of any records of Black-collared Starling nests holding both juv starlings & juv Asian Koels, but that may be due to lack of observation during the breeding season. One recent nest in Long Valley held two juv Asian Koels only. It's possible that any chick starlings may quickly starve to death in competition with the chick koels.

David

ddavid

For the record:

Black-collared Starling feeding Asian Koels at nest. Long Valley, August 11th.

David




[ Last edited by ddavid at 17/08/2012 11:40 ]

wcaptain

Perhaps the no of eggs laid by cuckoo relates to the size of froster parents.

For the common cuckoo, the size of froster parents are usually like "Common Tailorbird", so one egg is enough, otherwise the froster parents are too exhausted.

For Asian Koels in HK, the froster parents are starlings/myna, so more than one egg is still ok and would not make the froster parents too exhausted.

HKBWS Vicky

I have seen a BC starling nest in LV with 1 koel and 1 starling juv some years ago (size a little bit larger than that in David's photo above). The koel juv showed aggressive behaviour in competing food from parents. However, I'm not sure if the starling juv survived.

Sze

真實示範：杜鵑幼鳥如何推原本同巢的寄養父母的鳥蛋落巢。
Sharing:Blind Cuckoo Chick
http://youtu.be/RDettPoRuNU

[ Last edited by Sze at 19/08/2012 01:00 ]