Impacts of rain on breeding success?

To: "'Michael and Janette Lenz'" <>
Subject: Impacts of rain on breeding success?
From: "Barbara Allan" <>
Date: Sat, 11 Dec 2010 13:49:28 +1100
The koels are still going strong in Page as well. We have at least three: an
adult male; an immature male; and at least one but more likely two females.
This morning both adults dropped into a neighbour's liquidamber and were
urged out by the resident wattlebirds; they then tried a nondescript large
bush nearby and were discouraged by a pair of Magpie-larks. The male is
currently doing the rounds of his favourite perches, koelling steadily. They
don't appear to be sampling prunuses but the adult male has been seen
tucking into loquats. In terms of breeding success, I'd be more than
surprised if we don't score a koel chick somewhere nearby as the adults have
been so persistent over several weeks, despite there being fewer host nests.

-----Original Message-----
From: Michael and Janette Lenz  
Sent: Friday, 10 December 2010 7:41 PM
To: David McDonald; chat line
Subject: Impacts of rain on breeding success?


Just a few comments and a bit of speculation, no science.

>From my days in Germany it was evident that wet summers meant poor breeding 
success in many species, notably the aerial feeders (swifts, swallows, 
martins), and species with open cup nests. There are difficulties in finding

sufficient food (for the parents, let alone the young) and keeping the nest 
content dry and warm. Prolonged wet weather can be very energy-demanding 
particularly when 're-fuelling' is difficult.

Here I have found the Pied Currawong to be quite sensitive to wet 
conditions, with fewer young reaching fledgling stage than were in the nest 
at the start (incl. finding dead young under the nest). This year I have not

seen many young P. Currawongs, and if so, at the most 2 young/pair. At the 
recent December woodland survey at Mt Ainslie I saw only a few fledglings 
from any species, and I assumed that the very wet weather has reduced 
breeding success (but several species were still on nests, several of those 
were most likely replacement brood attempts). Even the Dusky Woodswallows 
(Jack Holland's nest workshop in Campbell Park in mid November showed them 
as abundant), were no longer very evident. Also there are only few 
indications of breeding success in the wider surroundings of my GBS site in 
Lyneham, on Lyneham Ridge etc. incl. common species (e.g. Magpie, Red 
Wattlebird) (a key exception so far are the Noisy Miners at the ANU; they 
seem to be indestructible!).

Even species which may have "dry" nest sites, incl. many cavity nesters, may

still be experiencing difficulties in finding enough food (e.g. Dollarbird, 
Rainbow Bee-eater and others) with consequences for their overall breeding 

I have also been wondering why Koels have only given brief, fleeting 
appearances this year in some of the areas where they have been breeding 
successfully in the past (e.g. Ainslie, Lyneham). Is this also weather 
related? Perhaps a reflection of limited numbers of suitable host nests at 
the right stage/time for dropping eggs in? With the mild winter/spring and 
some early welcome rains, several species have started nesting earlier than 
usual, this would have been followed by difficult conditions for follow-up 
broods (e.g. Red Wattlebird, Magpie-lark, Noisy Friarbird, potential hosts)?

We also have to keep in mind that rainfall in different parts of Canberra 
can vary greatly; hence conditions and circumstances are not uniform across 
town. What may apply to some parts of our area, may not be relevant in 

Michael Lenz

From: "David McDonald" <>
Sent: Thursday, December 09, 2010 4:48 PM
To: "CanberraBirds" <>
Subject: Impacts of rain on breeding success?

> Hi, I'm wondering what science tells us about the impacts of extended wet 
> periods, such as we are now experiencing, on bird breeding success, and 
> the mechanisms involved. Anyone out there on top of this topic?
> Thanks - David
> -- 
> David McDonald
> Canberra Ornithologists Group email lists manager
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> M: 0416 231 890
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