Annual flock-count results are in
This year’s Annual Count has helped us identify a lot of new information – including the location of the larger flocks so they could be flock-counted.
The purpose of a flock-count is to provide information on the sex ratio of the flocks, including the percentage of juveniles. Identifying how many juveniles are in a flock, gives us insight into reproductive success of previous years.
Flock-counting involves distinguishing adult males (black plumage, solid red panel in tail) from the rest (yellow spots in plumage, barred tail panel with red and yellow). The non-adult males are either females or juveniles.
As with other similar species, the Red-tail has an approximately 50:50 ratio between the sexes in adult birds. So if a flock has 39 per cent adult males then it is assumed that the flock also has 39 per cent adult females. Thus if there are 39 per cent adult males and 39 per cent adult females totalling 78 per cent adults, the remaining 22 per cent of the flock must be birds less than four years old (when young males assume the adult plumage).
It is very difficult to count individual Red-tails when they are in a tree canopy feeding or roosting. The most opportune time to flock-count is when the birds leave the tree canopy and go for a drink, before roosting for the night. Red-tails have been recorded drinking from livestock water troughs, dams and even puddles in the middle of muddy tracks. In a season like the one we’re having that means almost everywhere! You’d be forgiven for thinking that’d make it easier; however it actually translates into many more places to search.
Luckily, this just provides another excuse to throw off the office shackles and get out into the field to see (a.k.a. objectively observe and gather scientific data) these beautiful birds. The field season has also allowed me to meet many of the land owners and dedicated Red-tail watchers. Thanks to all who have provided assistance and tips on the movements of Red-tails in their patch.
This year’s results give an indication of the success of the previous breeding season. The percentage of males to date is 42 per cent and 16 per cent birds less than four years old. The Red-tails have been breeding, but it could be better. Let’s hope this season of plentiful rain translates to plenty more chicks.