I have looked at some data from the COG Garden Bird Survey (which includes
measures of both numbers of birds x species and number of observer weeks)
for Crimson Rosella and Gang-gang Cockatoo in the broad Canberra area. The
data covered the first 30 years of the survey.
To my surprise adjusting for observer effort doesn't affect the pattern of
numbers recorded greatly. April-May is still well above September-October
for both species. So other factors must be in play.
Martin Butterfield
http://franmart.blogspot.com.au/
On 19 December 2017 at 23:11, Penny Brockman <> wrote:
> No doubt I will get shouted down but I think it is a mistake to equate
> Australian bird behaviour with that of northern hemisphere birds. We don't
> have the long cold dark winters and short days that either force many birds
> to migrate south (with all the risks) or see the winter out and likely run
> short of food and starve or freeze to death.
>
> My London son feeds birds in his garden throughout the year, as my family
> did when I was young. They desparately need this in winter when the ground
> is frozen hard or covered in snow and days dark and short. There are now
> more birds in the middle of British cities than in many parts of the
> countryside where modern farming methods have reduced habitat, spread
> herbicides and pesticides, and cleaned up what were once scrubby patches in
> which the birds bred and foraged.
>
> Our birds function according to our weather which is (to be it mildly)
> unreliable - often extremely wet or extremely dry - and they are
> accordingly opportunistic breeders. I have at the end of my garden
> currently a pair of Torresian Crows and a pair of Magpie Larks - both have
> just seen off their first season's nestlings, started end October, and the
> crows are now re-building their old nest and the Pee Wees already
> incubating in their old nest. The local Red Wattlebirds are also into
> their second breeding sessions.
>
> A question I have on the Pee Wees is - they fledged 4 nestlings, No. 1 and
> 2 on one day, no. 3 next day and no. 4 on the third day. I observbed them
> usually close together in trees at the end of my garden for 3 days, and
> then they were not seen again and the parents were next rearranging the
> nest. Had these fledglings been eaten by the crows' two active and just
> weaned youngsters or other predators, or had they already been left by
> their parents to look after themselves? (unlikely according to Hanzab.)
> During this time the young crows and some kookaburras were being harassed
> constantly by Willie Wagtails, Figbirds, the Pee Wees and Red Wattlebirds,
> all breeding in the same patch of trees ? These two immature crows have now
> also vanished, I think driven off by their parents as I saw some rather
> nasty interactions between the adults and immatures.
>
> Always fascinating to watch what goes on in a small patch, lots of
> questions unanswered.
>
> Happy birding over Christmas and New Year to all,
>
> and weren't the Aleutian Terns great! - Farquahar Inlet, near Old Bar on
> NSW Mid North-Coast for those who maybe haven't yet heard about them.
>
>
>
> n 19/12/2017 3:31 PM, Martin Butterfield wrote:
>
>> Taking Sonja's point a step further, another possibility is that a lot of
>> birds die over Winter.
>>
>> When I lived in the Eastern US someone authoritative expressed this in the
>> following terms (not rigorous but I think the concept works) :
>>
>> 1. At the start of a breeding season there are x birds in the US.
>> 2. Each pair of them rears on average 2 young (which is another 'x').
>> 3. Thus at the end of Summer there are 2x birds.
>> 4. However by the start of the next breeding season there are only x
>> birds again.
>> 5. Why isn't the US knee-deep in dead birds?
>>
>>
>> The answer offered to the final question is that a lot of them don't make
>> it across the Gulf of Mexico! The timing of point 3 in Australia would
>> be
>> April-May and the timing of point 4 is pretty much September-October.
>>
>> Martin Butterfield
>> http://franmart.blogspot.com.au/
>>
>> On 19 December 2017 at 15:15, Sonja Ross <> wrote:
>>
>> Hi Don,
>>>
>>> One reason in Victoria is that September and October tend to be our
>>> wettest months so birders may possibly spend less time out birding. It
>>> could also be that if the birds are breeding in our spring, at least for
>>> part of the time, one of a pair could be sitting one eggs.
>>>
>>> Another could be that April is often Easter when people are often out
>>> camping and birding. Successful breeding would also show up in increased
>>> numbers then before winter.
>>>
>>> Sonja
>>>
>>> On 19 December 2017 at 13:38, Donald G. Kimball <>
>>> wrote:
>>>
>>> Sorry Martin but are you suggesting there should be more parrot sightings
>>>> in Sept/Oct? I thought there were more records and birds present in
>>>> April/May. Perhaps I need to scrutinize my findings more. Thanks for
>>>> your
>>>> imput mate!
>>>>
>>>> Don
>>>>
>>>> On Mon, Dec 18, 2017 at 1:37 PM, Martin Butterfield <
>>>>
>>>> wrote:
>>>>
>>>> Donald
>>>>>
>>>>> Are you adjusting for the total number of checklists submitted? If
>>>>>
>>>> there
>>>>
>>>>> are more lists in Apr/May than Sep/Oct one would expect more records of
>>>>> parrots.
>>>>>
>>>>> Martin
>>>>>
>>>>> Martin Butterfield
>>>>> http://franmart.blogspot.com.au/
>>>>>
>>>>> On 19 December 2017 at 07:42, Donald G. Kimball <>
>>>>> wrote:
>>>>>
>>>>> I use E-bird a good deal like many I suspect. I have noticed a
>>>>>>
>>>>> pattern in
>>>>
>>>>> parrot data. I looked at aproximately 30 species of parrots in NSW,
>>>>>>
>>>>> VIC,
>>>>
>>>>> NT and noticed that there are more recordings/sightings for most
>>>>>>
>>>>> species
>>>>
>>>>> in
>>>>>> April/May as opposed to Sept/Oct.
>>>>>>
>>>>>> I have my own ideas as to why this is so but would love some input
>>>>>> from
>>>>>> local Aussies.
>>>>>>
>>>>>> Thanks very much!
>>>>>>
>>>>>> Don Kimball
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