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Costa Rican Taxonomy (1 Viewer)

Mysticete

Well-known member
United States
Considering that there is a lot - really a lot - of arguments by song, I'd like to ask an amateur question that's probably has been answered scientifically, I just don't know about it: how much do we know about what sounds different to the birds? Considering that even different humans have vastly different capabilities regarding judging sounds, I would dare to expect that birds will be even more different to us in that respect. Not only by different frequency sensitivity curves but by different pattern recognition, different stress on difference in tone vs. rythm etc... Do we have a clear algorithm that we could run two sounds through and say "this sounds recognizably different to this bird/genus/family/all birds"?
I mean, that is kind of the basis of playback experiments. Does a bit initiate an appropriate response if it hears the song/calls of a different population. Lack of response with a suitable sample size could be very indicative that two populations are different species. It's the intermediate levels of response, where they are sometimes ignored or only have a weak response where things get dicey.
 

THE_FERN

Well-known member
Considering that there is a lot - really a lot - of arguments by song, I'd like to ask an amateur question that's probably has been answered scientifically, I just don't know about it: how much do we know about what sounds different to the birds? Considering that even different humans have vastly different capabilities regarding judging sounds, I would dare to expect that birds will be even more different to us in that respect. Not only by different frequency sensitivity curves but by different pattern recognition, different stress on difference in tone vs. rythm etc... Do we have a clear algorithm that we could run two sounds through and say "this sounds recognizably different to this bird/genus/family/all birds"?
The standard way to assess this is playback experiments. Play the song of one to the other and assess the reaction. Has to be done carefully, of course
 

opisska

rabid twitcher
Czech Republic
Good responses, thanks! i am a bit smarter now.

Also, I have started to think how practical a UV camera would be for better ID :)
 

Mysticete

Well-known member
United States
It does make me wonder...Could UV coloration differences be the next ID frontier. No idea on how you would implement that, but anything that could potentially make flycatcher ID easier!
 

njlarsen

Gallery Moderator
Opus Editor
Supporter
Barbados
It does make me wonder...Could UV coloration differences be the next ID frontier. No idea on how you would implement that, but anything that could potentially make flycatcher ID easier!
you would certainly need a new set of field guides!
Niels
 

pbjosh

missing the neotropics
Switzerland
It does make me wonder...Could UV coloration differences be the next ID frontier. No idea on how you would implement that, but anything that could potentially make flycatcher ID easier!
I’ve wondered this very thing quite a bit over the past 5 years or so.
 

pbjosh

missing the neotropics
Switzerland
Just getting back to the voice issue: for non-passerines and as far as is known the vast majority of sub-oscine passerines, song is genetically coded, not learned. So if two birds do not recognize each other, it means they're genetically programmed to a degree that they do not have a conspecific response. Of course, conducting playback experiments has to be done rigorously and one has to have contextual understanding of what family/genus is in question. IE, a lot of tapaculos will approach tape of any other tapaculo if they happen to be close. For oscine passerines, song is learned, so it gets a lot more confusing. You have cases like Golden-crowned Warbler where you have distinct populations with some morphological differences and wildly different songs where common sense says they are almost certainly congeneric but specifically distinct. But a good example of messy birds are House Wren, or Brushfinches (Atlapetes) where a lot of divergence times are relatively recent, the morphology / coloration is not a good indicator of how different they are, the songs are complex, varied, and all learned, and the genetics sometimes don't match up to what one observes in the field. It again reinforces that "species" is a human concept and evolution leads to things that don't neatly fit. But many/most of these cases are not "House Wren" level of complexity, they are dead obvious genetically coded songs that vary across geographic boundaries. The burden of proof is more on "maintaining clearly different birds as one species" rather than splitting in a lot of these cases, to be fair.
 

njlarsen

Gallery Moderator
Opus Editor
Supporter
Barbados
Regarding House Wren - notice proposal 2022-B-10
Niels
 

Mysticete

Well-known member
United States
Although Sadly the House Wren proposal only deals with the Caribbean, and not the whole Southern vs Northern House Wren situation.
 

njlarsen

Gallery Moderator
Opus Editor
Supporter
Barbados
Although Sadly the House Wren proposal only deals with the Caribbean, and not the whole Southern vs Northern House Wren situation.
If accepted it will be a small opening to do more perhaps? Anyway, for me as a Caribbean resident this also has value.
Niels
 

THE_FERN

Well-known member
Very surprised they want to recognise Northwestern crow again. AFAIK, not identifiable by voice, appearance or genetics, only location !
 

Snapdragyn

Well-known member
It does make me wonder...Could UV coloration differences be the next ID frontier. No idea on how you would implement that, but anything that could potentially make flycatcher ID easier!
Hmm, maybe we'll have bins with UV filters on them? Or at least some sort of lens cap that can be placed on them at need?
 

opisska

rabid twitcher
Czech Republic
But human eye doesn't see UV light, so the result would be just black. There are some very near UV filters for cameras through which you can get some signal with some cameras, but that's honestly more "really violet" than UV and it's not great. Most glass gets really opaque very fast below 360 nm and even if you can get a plastic lens, a lot of cameras have more blocking elements close to the chip itself - and the chips often aren't that hot in UV either. Solutions exist, but are there any that would be able to get a reasonably distant bird? We all know that photographing birds even in visible light isn't always easy ...

I have so far not been able to find a clear answer as to what wavelength of UV the birds actually see, I expect it to not be too far from the visible range simply because there isn't that much further UV light around us to see with anyway (and the birds don't seem to be carrying UV torches with them), but it's still challenging.
 

James Lowther

Well-known member
I have so far not been able to find a clear answer as to what wavelength of UV the birds actually see, I expect it to not be too far from the visible range simply because there isn't that much further UV light around us to see with anyway (and the birds don't seem to be carrying UV torches with them), but it's still challenging.

Down to 300nm according to Wikipedia Bird vision - Wikipedia
Cheers
James
 

opisska

rabid twitcher
Czech Republic
Heh, that didn't occur to me to check :) According to the plot there, the peak is 370, that may be achievable with normal cameras just with filters - on a bright day.

edit: i found some information on DSLRs and UV - Canon DSLR EOS camera’s and Ultraviolet (UV) photography « Mickyj's Mindspillage - it's old, but the situation is probably same or worse. Seems to dramatically prefer old (CCD-based) Nikkons, there are even dedicated lenses. Canons have to be modified, but all CMOS stuff is disadvantaged. Overall seems like a rather difficult job. Maybe I should borrow a CCD camera at work, rig a power source and RPI on it for field use and get a filter and try :)

edit2: really nice filter discussion here - Infrared block, broad UV and visible pass filter? - also explains that wjild filters with maximum at 355 are easily available, you'll be getting 380 images due to multiplication of sensitivity and solar radiation curves. Still apparently pretty interesting. I am now pretty convinced to try this with astronomical CCD cameras and see where it goes, will make a more appropriate thread if I get results.

edit3: I know this is quite off-topic, but I have even found a workable filter - the Johnson U filter used in astronomy is basically perfect, the ones that we have have a maximum a 360 and cut at 390, with no IR leak at least until 1200. Those are completely useless for us, but for some reason, we have sets of filters that include them. Tomorrow at work I'll try to find all the pieces and maybe I'll be able to start imaging birds :)
 
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iain tomlinson

Well-known member
Thanks for posting this. I am curious about the potential split of Vermiculated Screech-Owl (Into Costa Rican and Skutch's). Are either of these taxa the same as the Choco birds in West Ecuador or the "Guatemalan" birds that occur on both coasts of Mexico? Or are they more localized to Central America? Thanks for any clarification. Thanks, Iain
 

Mysticete

Well-known member
United States
Thanks for posting this. I am curious about the potential split of Vermiculated Screech-Owl (Into Costa Rican and Skutch's). Are either of these taxa the same as the Choco birds in West Ecuador or the "Guatemalan" birds that occur on both coasts of Mexico? Or are they more localized to Central America? Thanks for any clarification. Thanks, Iain
Thankfully the screech-owls are one of the examples that are discussed in more detail. The authors argue that Middle American Screech-Owl consists of 5 species:

Skutch's Screech-Owl (Megascops new sp.): endemic/near endemic? to Pacific slope of Costa Rica. It is suggested that it might be most closely related to Choco Screech-Owl, but still (probably?) separate

Costa Rican Screech-Owl (M. vermiculatus): Eastern Nicaragua through NW Panama

Choco Screech-Owl (M. centralis): no range given but presumably the same range given elsewhere

West Mexican Screech-Owl (M. hastatus): West Mexico...duh

Mesoamerican Screech-Owl (M. guatemalae): Eastern Mexico to western Nicaragua
 

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