Date: 10/18/25 10:55 am From: Joe Morlan via groups.io <jmorlan...> Subject: Re: [pen-bird] Red Crossbills at Skylawn Cemetery.
Al & All,
Thanks for the feedback. I noticed this journal article..
Martin, R., Rochefort, J., Mundry, R. and Segelbacher, G. (2024), Fast
cultural evolution of Crossbill (Loxia spp.) calls in the Palaearctic.
Ibis, 166: 267-284. https://doi.org/10.1111/ibi.13253
...documents significant change in crossbill calls over relatively short
periods of time. I have personally witnessed crossbills at Skylawn switch
calls. Most types including Cassia rarely switch calls, but it does happen.
On Thu, 16 Oct 2025 22:44:20 -0400, <chucao...> wrote:
> All crossbill calls are learned, ALL of them. But the learning and
>copying of calls is something that they do for flock cohesion, and for type
>matching (bill/ecological type matching). It is not random copying and
>mimicry. Cassia Crossbills have been wandering widely away from Idaho since
>the big fires there. Crossbills move massive distances when their core tree
>or trees do not have food. All crossbills move. There is no such thing as a
>resident crossbill, at least not long term. The Cassia situation is special,
>but it was incorrect to think they were resident. It was better to have
>thought of them as having a particularly stable food supply, such that for
>long periods of time they did not move out of their spot. But large fires
>did do this to them, with many records in Colorado, and later the ones in
>California.
> We need a really thorough genomic study of crossbills to sort out what
>is going on, there are no birds like them. We can have sympatric breeding
>without mixing (at least not commonly). Yet they can changeable home ranges
>and next breeding season encounter an entirely different vocal type where
>they breed. Nothing is quite like them. We need more data, and open minds to
>sort out crossbills. I look forward to when more information is available.
>
>Alvaro
>
>Alvaro Jaramillo
><alvaro...>
>www.alvarosadventures.com
>
>-----Original Message-----
>From: <peninsula-birding...> <peninsula-birding...> On Behalf Of
>Joe Morlan via groups.io
>Sent: Thursday, October 16, 2025 9:33 PM
>To: <peninsula-birding...>
>Subject: [pen-bird] Red Crossbills at Skylawn Cemetery.
>
>This morning I visited Skylawn hoping to photograph the Red Crossbills which
>have been reported there. My eBird list with photos, video and voice
>recording is here..
>
>https://macaulaylibrary.org/catalog?taxonCode=redcro&subId=S279761664&view=g >rid
>
>I did not recognize the calls so I contacted some experts who said that the
>call I recorded closely resembles type 12. However that type is centered in
>the northeast and has only one previous California record. Another
>possibility is the enigmatic type 7, the rarest call type with unknown call
>variation and unknown range. For now it remains a mystery. I welcome other
>opinions.
>
>Some of you may recall when the Cassia Crossbills were at Skylawn October -
>December 2023 with voice recordings by multiple observers confirmed by
>experts. This would have been a first California record except that it was
>not accepted by the CBRC. Perhaps for good reason. Cassia Crossbill was
>described as a species with limited range confined to one county in Idaho.
>Then records started in Colorado. But California was perhaps too far a
>stretch for the committee when it became apparent that crossbills may
>imitate other call types.
>
>Regardless, it would be good to get better recordings of these birds. If it
>can be confirmed they are type 7, I think that would be very interesting as
>few such recordings exist.
--
Joseph Morlan, Pacifica, CA
