Hi Philip
I thought this was a very plausible analysis. I have two comments:
- When I observed my first Channel-billed Cuckoo with foster parents, there were two chicks in a magpie nest
(I still feel sorry for the magpies). I just happened to have been there when the young fledged. But there was an adult nearby calling. I reported to this group and I recall that someone said there was evidence of association amongst CBCs. I note that
HANZAB makes no mention of association but good information on multiple laying in host nests.
- Speaking of HANZAB, there is some suggestive text that there may be association amongst Koels. In the section
“Relations within family group” (vol 4, p765), there are two references to adults perching nearby for some days after the young hatched. As I say, only suggestive but nonetheless intriguing.
David Rosalky
From: Canberrabirds <>
On Behalf Of Philip Veerman via Canberrabirds
Sent: Sunday, 12 January 2025 10:09 PM
To: 'shorty' <>
Cc: 'CanberraBirds email list' <>
Subject: Re: [Canberrabirds] More on the Koel
Sorry but I suspect, to take this further can only be a bit tedious and repetitive (apologies, I find it so, but here goes anyway). Because these are nest parasites,
there is no actual reason to think that there should be any interaction between adult cuckoos and young ones. I can’t think of any good reason why there would be. It is obviously not required, as the young Koels clearly are capable of making it on their own,
without any assistance of adults. Being not required in every case, it won’t be in their instincts to have such a behaviour. Because it is a complex set of behaviours to come about. It is may be possible, but very unlikely, that the adults, especially adult
males, can have any way of knowing who is their direct offspring. So why evolve a counter intuitive behaviour? For what it is worth, many migratory birds have adults leave the nest area earlier and separate from the young birds.
So I suggest, in terms of scientific method, the null hypothesis has to be that there is no social connection between the Koel adult and chicks. The null hypothesis
does not need to be proven (although can be disproven). The alternate hypothesis (thus available to demonstrate) is that there is a social connection there. That there is so little (if any) evidence that there ever is, does not make it overly useful to search
for reasons why there should be. The observations reported are (I suggest) simply that of coincidental proximity. As the species has become quite common here, proximity is bound to happen. Our Canberra environment seems to be a special case, the birds that
arrive here seem to stay for the whole summer (don’t move on), as they are not very often found outside of the Canberra region. This is probably because of food. So the adults are sort of stuck here while the kids grow up. That is probably why the occasionally
seen proximity of adults and juveniles happens here. But no substantial connection has been shown. If it was important it would be noticed a lot. However, that this proximity happens infrequently enough to be thought interesting to comment on, is of itself
supportive of that it is not of significance and is likely to be simply coincidental. Given that the normal situation of a parasite is to have no contact, as normally the parents would have long moved away, if it was important (or even useful) to have this
contact, for example for adults to (amazingly) find their own young and guide them on migration, then the behaviours to facilitate something so very difficult, would clearly need to be very highly developed. It clearly is not.
I am not suggesting I know whether the answer to this is yes or no (or if anyone does). But I think there is nothing to see here. Just that there should be a better
start point to clarify if there is a basis for a question and then if there is, what direction to approach the question from. .
Philip
From: shorty
Sent: Sunday, 12 January, 2025 5:17 PM
To: Philip Veerman
Cc: CanberraBirds email list
Subject: Re: [Canberrabirds] More on the Koel
"I don’t really see that there is a basis to think that is an interaction, unless there actually is a contact." I don't see why there is not.
"Sure those theories are sort of plausible but is there any basis to even raise the theories?" Any reason to not?
"Why do the adult males NOT bother the juveniles but ignore them?" Are you sure they ignore them? Evidence?
On Sun, Jan 12, 2025 at 4:54 PM Philip Veerman via Canberrabirds <> wrote:
I don’t really see that there is a basis to think that is an interaction, unless there actually is a
contact. It is a proximity. The adult Koel just happens to still be there (either because of food availability or the chance to find new breeding chances (or both) and they are making normal adult calls. Sure those theories are sort of plausible but is there
any basis to even raise the theories? Is there a question to be answered? It is fairly normal that they are just around in the same places anyway. Most years when I find juveniles, there are still adults nearby.
Actually I find the more curious question is the opposite. The alternative is that there is avoidance
that might need explaining. Seeing as to us, juvenile Koels look so similar to adult females (smaller and different head colour) and that adult male and female Koels have such vigorous interactions, why do the adult males NOT bother the juveniles but ignore
them? How to they recognise the disinterest? I guess because adult females respond to adult males (especially vocally) but juveniles do not.
Philip
From: Canberrabirds
[
On Behalf Of jandaholland--- via Canberrabirds
Sent: Sunday, 12 January, 2025 3:00 PM
To: 'shorty'; 'Canberra birds'
Subject: Re: [Canberrabirds] More on the Koel
Many thanks Shorty, for your very interesting observation/
The possible reasons for Koel adult/fledgling interactions are not clear, with at least 2 theories being raised in the past, 1) to imprint the call or 2) to escort the fledglings
N. Yours giving the ko-el call (which I heard up to Christmas but not on my return) is very interesting, and perhaps lends some support for the former, since early January would seem too early for them to migrate.
My last summary (with back references) of adult/fledgling interactions is in Section 5.4 of CBN
45, 293-310 (2020) for the 2019-2020 season. I note John Harris’ adult was giving the
wirra wirra call. There were very few such observations in the bumper 2020-2021 season [Section 4.8 of CBN
46, 119-144 (2021)].
Jack Holland
From: Canberrabirds
<>
On Behalf Of shorty via Canberrabirds
Sent: Sunday, 12 January 2025 12:52 PM
To: Canberra birds <>
Subject: [Canberrabirds] More on the Koel
Today I have had both the juvenile present and also an adult male calling. I took a recording where you can hear the juvenile beginning and the adult calling, they were about 20
metres apart in separate trees. Recording is on my checklist.
--
This is the email announcement and discussion list of the Canberra Ornithologists Group.
Emails posted to the list that exceed 2 MB (2,000 kB) in size, including attachments, will be rejected.
All emails distributed via the list are archived at
http://bioacoustics.cse.unsw.edu.au/archives/html/canberrabirds. It is a condition of list membership that you agree to your contributions being archived.
Canberrabirds mailing list
https://lists.canberrabirds.org.au/mailman/listinfo/canberrabirds
|
ATT00001.txt
Description: ATT00001.txt
|
