breeding behaviour of a community of
birds in relation to the El Nino Southern
Oscillation and gained a true picture of
how important this phenomenon is for
birds in our woodland communities.
THE STUDY AND ITS BENEFITS
In a 10ha plot of woodland in southern
coastal New South Wales, a group of
researchers monitored how many pairs of
native birds nested each season. There are
several brilliant aspects to this research
that I think will go unnoticed by the
majority of readers looking through the
research paper but which I do think are
worth highlighting.
The fi rst important note is that the
research was kept simple and just
measured how many pairs of the target
17 bird species attempted nesting. Too
often these days the world is making
simple questions complicated and often
obscuring the true target of the question.
This is not to say that it was easy counting
nesting attempts of that many species every
breeding season over 17 years. I know these
woodlands, and putting-up with ticks and
leaches, not to mention inclement weather,
is no easy task over such a long period.
This brings me to another important
point, the length of the research. Initially
the work was commenced by Stephen
Marchant in a study that lasted 10 years
and concluded in 1984. Cleverly, the
recent authors added to this work by
going back to the same site and picking
up where Stephen had stopped. Across
the world there are probably hundreds or
even thousands of vacated study sites that
could offer continuing useful data but are
forgotten when the researcher moves on to
new subjects. All too often good ecological
research is thwarted by the limited length
of studies and concluded before the real
messages become obvious. This is mostly
a problem because the people with money
want quick results and are not prepared to
wait until the big questions are resolved.
Indeed, this is just one of the many reasons
innovation is being lost because we want
quick answers yet know nothing about the
basic facts.
FINDINGS
The fi rst fi nding of the study is perhaps
not surprising to an audience such as
ourselves but, nonetheless, important
and new to Australian science. There is
a positive relationship between SOI and
the number of nesting attempts. When
the index was positive and rainfall was
greater than 300mm during the breeding
season, more pairs attempted nesting and
the reverse was observed when SOI was
negative. Given that rainfall is positively
correlated with the SOI, you would be
forgiven for thinking that birds are only
reacting to rainfall and, when there is lots
of rain, they breed. Well, this is sort of true
but, in odd years where the SOI was zero
and rainfall did not correlate with the SOI,
the birds followed the index trend rather
than the rainfall and did not breed. These
unusual situations revealed that the birds
were evaluating the value of the coming
breeding season in the months prior to
rain which, for our calculations, correlated
with SOI values between April and July.
Now, I think it is safe to assume that
birds are not sitting there working out
the SOI values themselves, but they are
certainly taking environmental cues about
the prospects of breeding a long time
before they begin nesting. At fi rst this
notion appears strange, possibly because
I have always been taught that Australian
birds are just quick to react to weather
conditions and nest when there is a change
for the better. We talk about how water
birds, such as pelicans, just appear out of
the blue at inland lakes and commence
breeding. But what if their faculties are so
acute that they are reading future weather
events months ahead?
In the case of woodland birds, I wonder
if it is also a small but signifi cant rise in
abundance of food during the months
before breeding that enables birds to breed
in an unpredictable climate. Most of the
17 species studied in this work would
have relied upon insects as their primary
food source and, in turn, insects feed on
plants. So the real indicator in the chain is
perhaps something to do with plant growth
or health.IMPLICATIONS
The breeding season in my bird room
does not start with putting nests into the
canary cabinets. Work starts months ahead
with conditioning both males and females
for the heavy workload of producing
eggs and feeding chicks. Watching birds
in the wild for a lifetime has taught me
an enormous amount of useful material
that can be adapted to better husbandry
of captive birds. An example is watching
Gouldian Finches eating sprouted seed at
the beginning of the wet season and during
their moult, or seeing Hooded Parrots and
Long-tailed Finches feasting on termites
in the months before breeding. My birds
are given sprouted and soaked seed daily
in the two months before egg production
starts and their soft food is carefully
rationed at the same time to ensure peakcondition before the hard work begins.
Wild birds are also building their body
conditions prior to breeding and it is
the successful individuals that procure
the best resources, producing the most
young. In poor years, only a handful of
birds breed because resources were poor
leading up to breeding. These may be the
more experienced individuals or just those
birds that found a good place over winter
with lots of food. In a good winter, there is
ample food for everyone, resulting in the
following nesting being more successful
for the community as a whole. I suspect
this is similar to how our aviaries and bird
rooms function. If good, high-quality food
is in the cage, birds will breed.
That last statement was obviously a
simplifi cation because there are many
cases where some people are very
successful and others experience poor
seasons even when they use the same
feeding regime. This leaves me wondering
if our birds are also gauging external
factors in climate or environment that are
beyond our control when they decide how
much to invest in breeding. Although most
people would say that breeding seasons
are generally positive under the controlled
conditions in which we keep birds, there
are always those odd seasons that are less
than anticipated.
In a canary room almost everything
is highly controlled, with temperatures
kept stable, water in plentiful supply and
only the best food in the dishes. Under
these conditions it would be diffi cult to
understand what could be very subtle
environmental effects. However, in
aviaries, birds are more exposed to
real climatic conditions and could be
evaluating environmental stimuli that we
do not see or understand. Humans are
very good at thinking they can control
everything but it is simply not true.
Understanding how birds in the wild
evaluate the environment around them
could be very useful for us at many levels
and I fi nd it particularly interesting that
the stimuli for breeding are being observed
months in advance.
So, to all the people out there with good
breeding records, why not check the SOI
over the last few years and see if there is a
correlation with breeding success and La
Nina. How interesting would that be?REFERENCES
Marchant, R, Guppy, S & Guppy, M 2016,
‘The infl uence of ENSO and rainfall on
the numbers of
breeding pairs in
a woodland bird
community from
south-eastern
Australia, EMU,
vol. 116, pp.
254–261.iiiiiiiin n n n nnnnn
rrrd dddddd
mmmmmmmUUUUUUUUUUU,,,,Pelicans are perhaps our best example
of positive breeding interactions with
continental changes in weather patterns