50 shades of bright

Although there have been many studies on fairy-wren ecology and behavior during the breeding season, little work has been done when the wrens are not breeding. The peak for RBW breeding here at Coomalie is supposed to be in February, placing our IRES experience right in the middle of the non-breeding season (and in the winter/dry season in the Northern Territory).  As expected, many of the wrens when we arrived were in medium sized flocks rather than the normal breeding season pairs. A fair number of males were spotty–either molting into or out of bright plumage, although since we were unable to catch a large number of birds until July, it is not clear which of their two annual molts they were in. However, it is now clear that in the past few weeks a number of males are molting into their nuptial black and red plumage, which is what is referred to as “bright” plumage as opposed to the “dull” female-like plumage. Other males are in eclipse plumage-still identifiable as males because of a few black feathers here or there and a few red (or orange!) feathers on their backs. It seems that the males are gearing up for breeding, although we don’t know if breeding will happen early this year or if they are simply prepping months in advance. Other studies on congeners have shown that the date that males molt into nuptial plumage is one of the best predictors of male extrapair success, thus being here when the birds are molting is great for getting data!

Adding further evidence that the males are gearing up towards breeding, I saw the first petal display of the year a few days ago. Males looking to show off to potential mates or partners find a nice flower petal or seed that compliments the crimson on their back (in this case the petal was pink) and carry it around to show off to the ladies. Bright male BEY carried around the petal for a good ten minutes before presenting it to a dull bird who took it and flew off with it. Is she going to choose him as a mate or extrapair partner? Only time will tell, although it clearly seems like a little bit of courting is going on during these non-breeding months. BEY was in a flock with at least 3 bright males and one spotty male, and although there was a little bit of kerfuffling between these guys, the wrens were definitely in a mixed flock and not in territories. Over the next couple of weeks I will hopefully be able to keep collecting colorband resighting data to be able to see how associations and relationships between individuals during the nonbreeding season translate into fitness during the breeding season.


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