Our long running study of Bearded Tits at Leighton Moss has continued, but the first indications are that there is a marked surplus of males this year. To date we have caught 20 adult males but only three females. Of the 20 males nine of them did not have a brood patch. In this species male and female share the incubation and both develop brood patches. The implication is that the males without brood patches are unmated. All of the nine were last years birds and several of them have been re-trapped in different sites so are moving around the reedbed.
We usually have a small surplus of males each year. There is quite a bit of evidence, based on retrap data to suggest that males are more likely to get caught than females. In the 18 years of the study in only 3 years 2003,2004 and 2006 did we catch more adult females than males.
However it is early days yet and further catches should clarify the situation. Young birds are now flocking and all indications are that it could be a good season.
One explanation for the apparent surplus of males may be that they survived the past cold winter better than the females. News from Poland is that the breeding population has crashed from ca 50 pairs in my correspondents study area last year to only 2 males and a female this year following an extremely cold and snowy winter. In another site he found four males and one female.
John
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