This is possibly not a comment on breeding and is certainly not science. However I have commented previously about the change in species of cuckoo apparent in Carwoola this year , with Fan-tailed appearing to replace Palliid and Shining bronze replacing Horsfields bronze. In the last couple of days both Pallid Cuckoo and Horsfields bronze have become evident again. I have no idea if this is a weather related change or just a coincidence, but might be something to monitor.
Martin.
On Fri, Dec 10, 2010 at 7:41 PM, Michael and Janette Lenz <> wrote:
David,
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 success.
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 others.
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
T: 02 6238 3706
M: 0416 231 890
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