A few comments to the recent messages from Martin
Butterfield and Philip Veerman on the topic.
Parents with dependent young (DY) indicates the
penultimate stage of raising a brood, the final one would be when the young
reach full independence. Sightings of parents with DY is certainly worth
recording and gives some indication of breeding success, certainly a clearer
indication than nest building, incubating or carrying food to the nest. And
rightly the Garden Bird Survey (GBS) has this category for breeding
observations.
What I would like see is that we have two
categories of ?DY? observations: (1) young raised within or in close proximity
of the GBS site in question and (2) young raised well outside the GBS site in
question and passing through etc.
Recording a DY event for your GBS site can be
straightforward, e.g. for the resident Magpie. This species is present in the
same territory all year round. Other species tend to leave the narrower
boundaries of their breeding territory and move over somewhat bigger areas once
they have to provide for dependent young. Many of our garden birds fall into
that category. This family may appear on your block from a few blocks up or down
the street. But if it is a species that you have encountered during the breeding
season within or close to your GBS site, I also would have no problem to give
your block as the site for the breeding event.
Other species such as the King Parrot breed well
outside the suburban GBS area (although the species is in all likelihood already
nesting in CNP close to town, but only in small numbers), but appear in great
numbers within Canberra once the young are fledged. Parents feeding begging
young are then a common sight (these observations often end up as DY breeding
records on the GBS charts). These DY observations are NOT of local breeding
events that can be identified with a specific GBS site. We certainly should
record such observations, no problem there: they can tell us various things
about the King Parrots, e.g. the length of the period young stay dependent and
will beg for food, level of breeding success between years etc. However, such DY
observations have to be clearly distinguished from those where the young
originate from within or in close proximity to a GBS site (house block and
surrounds).
Depending on the species we will find
many variations between the extremes of the Magpie and the King Parrot. And in
many cases a DY observation of a given species known to breed within
Canberra and appearing
at a GBS site, may have originated from well outside the actual GBS site where
it is recorded. As I said above, I would like see us have two categories of ?DY?
observations: (1) young raised within or in close proximity of the GBS site in
question (and only the COG member will be able to make that decision, based on
observations throughout the breeding season) and (2) young raised well outside
the GBS site in question (a significant distance in the case of the King Parrot)
and passing through etc.
Observations from category 1. could be
plotted on a map to show the breeding distribution of a given species in urban
Canberra, observations
from category 2. would not be suitable for this. They can also be used to tell
us something about the biology of a given species.
With the end of the current GBS year approaching,
it would be great if GBS organisers could sort this out and provide relevant
instructions, assuming the issue is considered important
enough.
Michael
Lenz
