[Birding-Aus] What is the function of Channel-billed Cuckoo calling flights?

[Laurie Knight]

Channel-bills are (apparently) a bit different from other cuckoos in
the sense that they are most likely to be observed calling while in
flight. In the last couple of weeks I have noticed groups of CBCs
raising a racket. This morning I saw a group of five flying and
calling together. I originally thought the calling flights might be
territorial or associated with nest raiding, but I am now wondering if
the calling flights play a role in "picking up" immature birds from
their hosts and inducting them in CBC "culture".

Has anyone studied this aspect of CBC behaviour?

Regards, Laurie.
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[Greg & Val Clancy]

As they call at all times of the breeding cycle I would think that the
suggestion that it is to 'pick up' immature birds would not fully explain
why they call in flight.

Regards

Greg
Dr Greg. P. Clancy
Ecologist and Wildlife Guide
Coutts Crossing
NSW

[Peter Shute]

What's the most CBCs you could expect to see in a flock? Do any other cuckoo species fly in flocks like that?

Peter Shute

[Nikolas Haass]

I've seen 25 Yellow-billed Cuckoos together - albeit on a small island (Dry Tortugas) during migration.

Nikolas

 
----------------
Nikolas Haass
nha...@yahoo.com
Sydney, NSW

________________________________
From: Peter Shute <psh...@nuw.org.au>
To: 'Greg & Val Clancy' <gcl...@tpg.com.au>; 'Laurie Knight' <l.kn...@optusnet.com.au>; 'Birding Aus' <birdi...@vicnet.net.au>
Sent: Tuesday, December 6, 2011 8:28 AM

[Stephen Ambrose]

I saw and heard a (very) noisy group of 10 CBCs in vegetation along Tarban
Creek (Riverglade Reserve), Hunters Hill (in Sydney) last Saturday. This is
the largest CBC group I've seen in this locality in the 8 years of regularly
visiting the reserve. However, in consulting HANZAB, foraging/roosting
groups of 30-60 individuals have been recorded elsewhere in the species'
range, and there is one record of >60 migrating birds.

Stephen Ambrose
Ryde, NSW

[Greg & Val Clancy]

We have recorded 30+ Channel-billed Cuckoos roosting on Susan Island,
Grafton, NSW and regularly see 12 or more congregating in fruiting fig
trees. They usually don't fly in one large flock though.

[Philip Veerman]

Interesting question. Presumably, like most migrant cuckoos they call for
social or sexual reasons when they arrive at their breeding areas. But I
don't think that is the question being asked. Which raises to me the idea
that yes they are cuckoos, but in their way of feeding they are different
from most cuckoos. They are mainly fruit eaters. I would think that fruit is
a geographically concentrated food source, as distinct from the more evenly
spread insect food source that most cuckoos use. So I propose (for
consideration, with no proof I hope you understand) that maybe it is the
calling related to finding food - if they want to share it that is, or maybe
it provides a way to assemble in groups at places with abundant food.

Philip

-----Original Message-----From: birding-a...@lists.vicnet.net.au

[mailto:birding-a...@lists.vicnet.net.au] On Behalf Of Peter Shute

Sent: Tuesday, 6 December 2011 8:29 AM To: 'Greg & Val Clancy'; 'Laurie

[Stephen Ambrose]

I think it is more likely to ensure "safety in numbers" especially while in
flight. A lone individual is more likely to be mobbed by a nest host species
(currawong or magpie) or preyed upon by a predator (large raptor) than one
that is part of a flock. An individual calling as it takes flight alerts
others to follow. Calling while in flight keeps individuals within a flock
close together, especially if they are flying at night.

Dr Stephen Ambrose
Ryde NSW

[Laurie Knight]

Well there is that, but CBCs often call when they are on their own
with no others in earshot. They call when they are high up and not
being mobbed, and they call when they are flying in circles closer to
the ground. I have never heard one call near a fruit tree.

The thing is that a lone CBC calling would seem to be a more obvious
target (given that it is calling attention to itself) particularly
when it is flying high.

I have heard CBCs make a bit of a chuckling call that might be similar
to a raptor.

Are there any published records of their behaviour when they are nest
raiding?

Regards, Laurie.

PS I am not sure that it was a grammatical necessity to change the
subject line. (I think that makes it a separate thread in the archives).

> -----Original Message-----From: birding-aus-
> bou...@lists.vicnet.net.au

[Allan Richardson]

I've not noted large aggregations of C-bCu's in the day but we did flush around 12 roosting together, while conducting nocturnal surveys out near Gunnedah NSW. It was late in the evening, the tree was an isolated individual surrounded by grassland and there were no fruiting trees nearby to my knowledge. The birds were clearly roosting together not in response to a food source, which made the observation very interesting to me. The time of year was late January (2011), which suggested a post-breeding group likely made up of many young birds and perhaps a few adults, unfortunately there was no way to tell, they disappeared into the dark very quickly. I guess we have no way of knowing how many C-bCu eegs are deposited in the nests of other birds throughout the breeding season, could it be possible that the the 12 were a pair and their reunited progeny for that year and/or previous years?? There have been rumours, but have we established whether post-breeding groups are related i
n any way? if so, is it intentional or just likely due to the birds living and then departing from the same general area???

I have watched C-bCu's luring Currawongs out of the nest, presumably to allow the female an opportunity to parasitise the brood. The birds fly high around a stand of trees where the Currawongs are nesting, calling loudly, and the Currawongs just cannot resist to try and chase them off. Perhaps the indiscriminate calling we hear by individuals or pairs is an endeavour to draw other birds out to alert the C-bCu's of occupied breeding territories???

Other than that I think we might be able to assume that C-bCu's call for some of the same reasons other birds call. We assume they don't establish territories, but most birds defend breeding territories or food sources within defined territorial bounds and it's likely that C-bCu's are carrying out similar breeding season behaviour, albeit not tied to a personal nest site (unless they view the nests of their surrogates as a resource worth defending). Territory posturing may then explain the calling aggregations. Other cuckoos appear to call as territorial proclamations: Koels are very competitive, Fantailed, Horsefield's Bronze, Shining Bronze, Brush and Pallid are very vocal and I recently noticed many a brawl amongst competing Pallids in the Goulburn area (NSW sthn tablelands) this spring, induced and fueled by calling individuals.

Certainly cuckoos are one of the easiest groups to attract by call, a suitable whistle to Shining Bronze is the easiest way to get a closer view.

Allan Richardson
Morisset NSW

>> -----Original Message-----From: birding-a...@lists.vicnet.net.au

[Stephen Ambrose]

I like Allan's hypothesis of CBCs calling or creating a commotion while in a
forest or woodland as a diversionary tactic to allow a female to sneak in
and parasitise a nest. This certainly makes sense to me.

Stephen Ambrose
Ryde NSW

Allan Richardson
Morisset NSW

[Judith Hoyle]

Hi All,

An interesting thread. Over the prevoius two summers (but not this one, for some reason) we had a pair of CBCs that appeared to maintain a territory in our street. Whilst they were particularly active/vocal in the early morning and evening we heard them at odd intervals throughout each day.

I find Allan's observations of multple birds roosting together particularly interesting. Early on in their stay, our CBCs had the expected interactions with the local Torresian Crows to get the female into the nest. However, they were here for at least a couple of months after that, keeping up with their aerial calling throughout that time. As we live in an area without an obvious source of fruiting trees, it got me thinking: were they maintaining a territory around their nesting sites with the aim of 'picking up' their young once they had fledged??

Regards

Judith

[Allan Richardson]

There are certainly some very interesting questions in relation to CBC's yet to be answered. Some very interesting observations in there.

[Stephen Ambrose]

Yes, I agree, it has been an extremely interesting thread. It seems likely
to me, based on contributions to this discussion, that the calling of CBCs
has multiple purposes. I think many of us tend to fall into the trap of
providing a single reason for a particular animal behaviour, but I propose
that in the CBC, at least, calling has the following purposes:

1. Early in the breeding season, males call to attract a mate and to also
proclaim a breeding territory. Advertising the breeding territory through
calling then continues throughout the breeding period.

2. Calling and flight displays are also used to attract the attention of
potential hosts (corvids, currawongs, magpies) away from their nest to allow
a female to sneak in and lay her egg.

3. Later in the breeding season CBCs call to muster fledged progeny,
especially if a single pair has parasitised several nests within the
breeding territory.

4. Calling while in long-distance flight, either between foraging &
roosting sites or on long-distance migration helps to keep the group(s)
together, thus providing safety in numbers. Perhaps another way of
protecting themselves, offspring and other close relatives when flying over
open areas and vulnerable to predation or mobbing?

It sounds like a great opportunity for a postgraduate project. What are the
purposes of the calls? Are there different calling patterns/visual displays,
each serving a different purpose? What is the genetic composition of calling
flocks that are on the move - are they family groups or do they comprise
unrelated/distantly-related individuals?

Stephen Ambrose
Ryde NSW

-----Original Message-----
From: Allan Richardson [mailto:alb...@bigpond.net.au]
Sent: Wednesday, 7 December 2011 8:36 PM
To: Judith Hoyle
Cc: ste...@ambecol.com.au; samb...@pacific.net.au;
birdi...@vicnet.net.au
Subject: Re: [Birding-Aus] What is the function of Channel-billed Cuckoo's
calling flights?

There are certainly some very interesting questions in relation to CBC's yet
to be answered. Some very interesting observations in there.

===============================

[robert burgoyne]

I agree with Dr Ambrose. On a recent trip up to north Queensland I saw groups of 3 and 5 birds flying together calling. The group of 3 near Gladstone I observed frrom time to time for an hour and they were not approached by other birds once. My observation of single birds however, especially in Alice Springs where I lived for 26 years is that they are constantly mobbed whilst alone and calling. I also noted in the Alice that two birds would often fly together towards their roost sites in the evening. I have also seen the unusual sight of a juvenile bird out of the nest being fed by two Torresian Crows whilst others of the same species were attacking it!

Rob Burgoyne

Message: 5
Date: Tue, 6 Dec 2011 15:44:26 +1100
From: "Stephen Ambrose" <ste...@ambecol.com.au>
To: "'Philip Veerman'" <pvee...@pcug.org.au>, "'Birding Aus'"

<birdi...@vicnet.net.au>
Subject: Re: [Birding-Aus] What is the function of Channel-billed
Cuckoo's calling flights?

Message-ID: <000101ccb3d1$bbbbde10$33339a30$@com.au>
Content-Type: text/plain; charset="us-ascii"

I think it is more likely to ensure "safety in numbers" especially while in
flight. A lone individual is more likely to be mobbed by a nest host species
(currawong or magpie) or preyed upon by a predator (large raptor) than one
that is part of a flock. An individual calling as it takes flight alerts
others to follow. Calling while in flight keeps individuals within a flock
close together, especially if they are flying at night.

Dr Stephen Ambrose
Ryde NSW

[Richard Jenkin]

Hi all

Also interesting, but annoying, they often fly around calling at night. Like
3 A.M. this morning outside our bedroom window !!

Dick

DUNGOG NSW (70kms North of Newcastle)

Lynn and Dick Jenkin
Tashkent Friesians
PO Box 92 Dungog NSW 2420
02 49921158
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