Can breeding inhibit moulting?

[GregH]

It's not too often I get to see my hen Diamond Sparrow as she is continuously on the nest. I've only had the pair for 12 months (unfortunately a sibling pair due to their rarity here in the Philippines)and in that time there have put down 18 nests. That unfortunate record could only occur because 83% of the eggs were clear or failed to hatch and of the 3 clutches that hatched only one survived beyond the first few days and from that pair only one fledged. The sad tale doesn't end there as I found the hen on the floor unable to fly and as her flight and tail feathers are in terrible condition - all the barbules and many of the barbs are missing. Her body condition is fine but I've removed her and will keep here away from her incestuous mate until she recovers. Can it be that by brooding for so much of the year her body "forgot" to moult? Has anyone else observed this and given that the birds here mainly moult around June will I have to wait another year for her to recover?

[jusdeb]

x

[GregH]

Well I had to do some research for myself into the interactions of moulting and breeding in birds. This may bore you to death but I found it quite interesting as this sort of information seldom comes out in finch focussed aviculture literature.

According to Berry (2003) annual moulting often coincides with brooding in wild birds because of reduced food intake during this period. During this time feathers are replaced and the reproductive system regresses and interestingly, at least in domestic hens having undergone an austerity induced moult there is a marked improvement in egg production and shell quality (Berry 2003). Hormones associated with egg production shut down during austerity induced moulting in chickens (Iwaswa et al 2002). Environmental cues other than food are also known to be involved in the cascade of events leading to the annual moult. Photoperiod (day-length) is probably very important to birds at higher latitudes as appears to be the case for the magang goose (Huang et al 2008), turtle doves (Loftus et al 1957) and I suspect canaries.

Inactivity and austerity aren’t an option for some species. In Wagner’s (1957) hummingbird study none have ever been found with “blood-quills” while breeding however non-breeding individuals in the same period do exhibit this sign of feather replacement. This would indicate that brooding does inhibit moulting in hummers but question remains does it in finches?

So what have I learned from this that I can apply to my hen diamond fire-tail to assist in her rehabilitation? Contrary to my feeling of humane treatment she doesn’t need pampering with all the insects, soft-foods and green seed that she’s been getting on a breeding diet. She needs to moult and that is induced through austerity and then I can reintroduce the high quality foods to assist in feather production. According to Mike Fidler’s work with Gouldians; two weeks on dry seed should so the trick and conveniently I’m going to Australia for two weeks in a few days time so I can shove her in the quarantine cage (and hope the sugar-gliders don’t escape again and eat her) while I’m gone and let our domestic helper take care of her.

Berry, WD. (2003) The physiology of induced molting. Poultry Science 82: 971-980
Huang, Y.M; Shi, Z.D; Liu, Z; Liu, Y; Li, X.W. (2008) Endocrine regulations of reproductive seasonality, follicular development and incubation in Magang geese. Animal Reproduction Science Volume 104:344-358
Iwaswa, A; Hishika, TA; Kato, Y; Doi, O; Kamiyoshi, M; Nakamura, T (2002) Changes in Thyrotropin Messenger RNA and Circulating Hormone Levels during Induced Molting of the Hen (Gallus domesticus). Journal of Reproduction and Development. 48:.489-496.
Lofts, B; Murton, R.K; Westwood N. J. EXPERIMENTAL DEMONSTRATION OF A POST-NUPTIAL REFRACTORY PERIOD IN THE TURTLE DOVE STREPTOPELIA TURTUR IBIS 109:352-358
Wagner HO (1957) The Molting Periods of Mexican Hummingbirds. The Auk, 74:251-257.