I have a big collection of bird books, including many that could be called ornithology text books. I thought that is an easy question I will consult them for
a definition. The first 7 of these - I would have thought most relevant books - do not even include the word fledging (or even variants of the word), in the index. So no help there. The 8th
and 9th books I consulted, defined the word fledgling or fledgling period as a time during which a young bird develops the ability to feed itself along with parental help, with no mention as to whether that occurs before or after leaving the
nest. If that is the case in some birds the fledgling period is a long time. The 10th one “The bird almanac” defines it as “Acquisition of the first true feathers by a young bird”. I believe the word origin refers to that aspect, that fledge refers
to feathers, even though it is not used that way anymore. And if it was, it would for most birds apply to the latter part of the nestling period. I stopped at that.
I think Martin’s suggestions are the main ones used in Australia. They would be understood that way by most of us. Even though none of these books support either
of these definitions. Of course it is complicated by that the precocial birds that are active and often able to run, swim and / or feed themselves from the day of hatching, but are covered in down and do not grow feathers until some weeks after leaving the
nest. Most of them are very active for a long time before they first fly. It is just a bit silly to talk of a day old bird fledging, even if it fits the usual use. Also the number 2 does not apply to birds that do not fly. So the use applying to a Tawny Frogmouth
which might stay in the nest tree for several days leaving and returning to the nest and might not apply to a duck, or rosella (that once they leave the nest are gone and do not return).
Philip
From: Martin Butterfield [
Sent: Friday, 11 November, 2016 9:11 AM
To: COG List
Subject: [canberrabirds] What is meant by fledging?
In the past I have come across two definitions:
-
a young bird leaving the nest ; and
-
a young bird taking its first flight.
Some people have said there is no difference between the 2 definitions.
This morning at 0530 the male adult was not in the nest and both chicks were vigorously flapping their wings. However take off did not happen, and Dad returned shortly thereafter. At about 0830
this was the situation.
The more adventurous chick is clearly out of the nest. It still hasn't flown but in the last 10 minutes there has been much stretching of wings. On past experience
the business of walking up and down a branch could go on for a couple of days, sometimes both chicks and Dad taking a stroll. I don't believe they have yet fledged.
