I won't get into the nesting of Koels and raptors but something that I
have noticed this year if that the male koel(s) in Kaleen are NOT giving
their typical, usual "coo-ee (or koel) call. I have only heard it twice
this season and then only very early when they first arrived. Both sexes
are giving their other regular calls, and a lot of funny calls that I
have not heard before. They are also NOT calling in the middle of the night.
Anyone else finding this? The birds were somewhat late in arriving in
Kaleen this year.
Mark
On 28/12/2018 4:55 pm, Philip Veerman wrote:
> Hi Con,
>
> As for the Channel-billed Cuckoo, its usual hosts are corvids and currawongs,
> so along with the Collared Sparrowhawk shows the meat eating is not a
> problem, even though the adults mostly eat fruit (and some meat). As for the
> Koel, there is no raptor small enough.
>
> Here is that "quite a few" again. Let's suggest that means 5 raptors that are
> smaller: Collared Sparrowhawk, two small kite species and kestrel & hobby. I
> also suggest that most raptors have a far more aggressive and dangerous nest
> defence than most passerines. Your last suggestion seems as good an
> additional reason as any. Or a variant is that there are not enough raptors
> to go around to maintain raptor-specific cuckoos. Either option would be hard
> to prove. Just because there is not such a situation now does not mean it
> could never happen or did never happen. Not all possibilities exist, at any
> one time. Which is what I was hinting at before. Maybe over past millions of
> years they have tried and been unsuccessful...... Who would know?
>
> You might also like to check out this variant:
> https://www.treehugger.com/natural-sciences/cuckoos-and-crows-teach-us-how-parasites-can-be-good.html
>
> Philip
>
> -----Original Message-----
> From: Con Boekel
> Sent: Friday, 28 December, 2018 4:21 PM
> To:
> Subject: Re: [canberrabirds] Why don't cuckoos...
>
> I don't know the answer but the question intriques:
>
> In terms of size. the Channel-billed Cuckoo is larger than quite a few
> Australian raptores.
>
> In terms of diet, why not a meat-eating cuckoo?
>
> In terms of raptors predating/killing the cuckoo, current species of
> cuckoos routinely evade/avoid their hosts, why not evolve to be able to
> evade/avoid raptors?
>
> One possibility is that raptors are the highest trophic level and there
> is not enough energy to go around to maintain raptors AND
> raptor-specific cuckoos.
>
> regards
>
> Con
>
>
>
> On 12/28/2018 1:56 PM, Philip Veerman wrote:
>> Cuckoos parasitise species smaller than themselves. Maybe that is needed to
>> get the chicks the ability to push the host chicks out of the nest. So just
>> on that basis there is not much option to target raptors. I don't know if
>> that is the complete reason. That is not to suggest that this has always
>> been the case through history or will remain so into the future. One rare
>> quoted example though is that the Channel-billed Cuckoo has been recorded to
>> parasitise the Collared Sparrowhawk. Size difference still applies. All
>> other examples I know of include passerines.
>>
>> Philip
>>
>> -----Original Message-----
>> From: Con Boekel
>> Sent: Friday, 28 December, 2018 12:23 PM
>> To: canberrabirds chatline
>> Subject: [canberrabirds] Why don't cuckoos...
>>
>> Geoffrey's musings reminded me of a stray thought occasioned by the
>> larger than usual numbers of Koels lurking visually but not vocally in
>> Upper Turner this year.
>>
>> One sighting involved several Koels and a Collared Sparrowhawk in the
>> same tree at the same time.
>>
>> Here is my question: 'Why don't cuckoos parasitize raptores?'
>>
>> regards
>>
>> Con
>>
>>
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