For female wrens, a happy life of nest-hopping
OVER the past week or two, there have been a number of reports of male blue wrens attacking their reflection in car mirrors and windows.
It happens every year in spring when the birds see the reflection, presume it to be an intruder and attack it with extraordinary vigour.
Once the nesting season is well under way, the wrens have more to do than brawl with the image, for there are young nestings to feed and protect.
That all sounds simple enough, but in truth the wrens are very complicated, complex little birds.
Superb fairy-wrens — that’s the full name of the blue wren — live in extended family groups of perhaps six or eight.
Only one is beautifully coloured, all the rest — females and young males — are brown birds.
It was once thought that this was a male with a harem, but the brown birds have one difference.
Some, the females, have brown tails while young males have blue tails.
It is an extended family group, adult male and female, and their young from their broods of the past year or two.
These young birds are “nest-helpers” assisting the adults feed and nurture the nestlings.
That is the simple part of the story.
When DNA analysis was first used into the study of birds, the wrens were ideal subjects. They were caught, their DNA extracted and analysed, but with a startling result.
Only about one in four of the young had the resident male as their father.
It was presumed that the males were seducing any female in the area, and a watch was put on them.
Then the second surprise — the males did not stray from the home area at all.
It was the females that were mating with males in adjacent family groups.
Promiscuous? Not at all, for what they were doing was ensuring genetic diversity in the family group, restricting the possibility of inbreeding over time. Wildlife information and questions can be sent to ppescott@gmail.com