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Northern Saw-whet Owl

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Old Saturday 19th October 2013, 07:58   #1
Richard Klim
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Northern Saw-whet Owl

Rick Wright, Birding New Jersey and the World, 18 Oct 2013: The Kirtland's.

Great article, Rick.

[Also, John Penhallurick: World Bird Info.]
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Old Saturday 19th October 2013, 15:14   #2
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What a nice article! It's long been my ambition to see a "Kirtland's" but all I've managed so far is the adult which turns up in my backyard every few years around this time. I've been checking out the likely spots regularly the last couple of weeks, but so far no luck.
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Old Saturday 19th October 2013, 22:26   #3
Larry Lade
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A very interesting read! We will begin our Northern Saw-whet Owl banding in a couple of weeks here in Saint Joseph, Missouri. I will keep an eye out for a "Kirtland's" though.
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Old Sunday 20th October 2013, 01:35   #4
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Thank you, Richard. Was very interesting. Provoked memories of high school senior year physics class. Mr. H, our teacher had taken us out to the bleachers in the football field, in pursuit of a discussion of momentum and the relationship of mass & velocity. One of our classmates discovered apparently a "Kirtlands" underneath the bleachers. Class evolved from one science to another, instantaneously. All these years, that rascal bird thought to be something else.
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Old Monday 21st October 2013, 10:32   #5
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I get a domain expired but this cache may work for a while.

My encounter with Kirtland's Owl.
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Old Monday 21st October 2013, 10:43   #6
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Quote:
Originally Posted by jmorlan View Post
I get a domain expired but this cache may work for a while.
Seems that I jinxed Rick's website by posting a link here!
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Old Monday 21st October 2013, 13:17   #7
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Thanks for the good word, Richard.
Trying to get the site back up and running --
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Old Wednesday 22nd January 2014, 16:50   #8
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Genetics of divergence

Withrow, Sealy & Winker 2014. Genetics of divergence in the Northern Saw-whet Owl (Aegolius acadicus). Auk 131(1): 7385. [abstract] [pdf]

Holt et al 1999 (HBW 5).
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Old Wednesday 22nd January 2014, 17:41   #9
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So they are saying that there is very low if any gene flow between these two populations. The populations are in contact at least part of the year. So doesn't that fulfill the criteria for biological species? AOU proposal anyone?

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Old Wednesday 22nd January 2014, 20:38   #10
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We examined the genetics of divergence in Northern Saw-whet Owls (Aegolius acadicus), in which a migratory form (A. a. acadicus) occurs during fall migration and winter, but not at other times of the year, in the range of a sedentary, island form (A. a. brooksi) on Haida Gwaii, British Columbia.
Why would there be gene flow when they breed in allopatry?
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Old Wednesday 22nd January 2014, 20:43   #11
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The discussion include wording (by memory, I have not gone back to find the quote) that the location of the islands are such that it would have been expected that some of the nominate birds would have stayed and breed there. My conjecture (which might be wrong!) of what they say is that there is enough overlap of the two forms in habitat choice etc that they cannot breed in sympatry so the resident form excludes the other from getting established on the island. It might be my conjecture.

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Old Wednesday 22nd January 2014, 20:52   #12
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BNA Online

Rasmussen et al 2008 (BNA Online)...
Quote:
Systematics
Geographic Variation

Morphology
A cline of increasing size with increasing latitude in e. North America (Tamashiro 1996). Color uniform across range of species except for the darker brooksi (see Appearance). Brooksi and a distinct and potentially disjunct population in the Southern Appalachians are both significantly smaller than the main-range population, both exceeding Amadon's (1949) 75% rule for subspecies delineation with correct classification rates of 100% and 76.5%, respectively (Tamashiro 1996).
Genetics
An allozyme analysis of 11 loci found low within-population variation for brooksi and an adjacent population in the Okanagan Valley (Tamashiro 1996). The same study found higher within-population genetic variation for southeastern populations of the Northern Saw-whet Owl, including the morphologically distinct Southern Appalachian population. This pattern suggests a glacial refugium in the se. United States during the Wisconsin Glacial Maximum with subsequent expansion northward as glaciers retreated (Tamashiro 1996). Fitting this pattern, sets of alleles of any population of Northern Saw-whet Owl form only subsets of the total set of alleles found in the Southern Appalachian population, except for 1 allele that was found only in a population near Green Bay, WI. Tamashiro (1996) found that the Southern Appalachian and Alleghany Plateau populations (DR = 0.005) are at least as genetically distinct from the main range population as is the brooksi subspecies (DR = 0.004) from the main range population (Green Bay population in this case).
Subspecies
Two subspecies generally recognized: the migratory Aegolius acadicus acadicus occurs over the entire range of the Northern Saw-whet Owl, whereas the non-migratory Aegolius acadicus brooksi is endemic to the Queen Charlotte Is. (Sealy 1998). Fleming (1916) named and described brooksi from three adult females and one juvenile taken in 1915 on Graham Is. Hybrids between acadicus and brooksi have never been reported (Sealy 1998).
The appearance of brooksi is very similar to that of A. a. acadicus except that brooksi is smaller (despite having a longer tail) and darker (See Appearance). The white underparts and spots on the remiges and wing coverts of acadicus are infused with buff (Tawny Olive, Smithe 1975-1981) in brooksi.
Although not generally recognized because it is based on one specimen of a juvenile of disputed origin (i.e., Oaxaca), a third subspecies, A. a. brodkorbi that would link the Northern Saw-whet Owl with the Unspotted Saw-whet Owl (Aegolius ridgwayi) was proposed by Briggs (1954).
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Old Thursday 23rd January 2014, 15:05   #13
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Does anyone know of vocal differences between these two forms?
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Old Thursday 23rd January 2014, 15:30   #14
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Vocal differences

Quote:
Originally Posted by Mysticete View Post
Does anyone know of vocal differences between these two forms?
Rasmussen et al 2008 (BNA Online)...
Quote:
Vocalizations
...
Advertising call: A monotonous series of whistled notes on a constant pitch. Can be heard up to 300 m away through forest and up to 1 km away over water (Swengel and Swengel 1987, Milling et al. 1997). Series generally begins with a relatively short upsweep in frequency to a relatively long and constant frequency that is followed by a brief drop in frequency at the end of the bout (Hill 1995). Whistled notes of acadicus are given on a constant pitch of about 1,100 Hz (Mean 1104.7, SD 59.5, n = 10, 1,030-1,205) at a rate of about 2/s (Fig. 3a). In Massachusetts, Tennessee, and North Carolina, Hill (1995) found that the notes of the advertising call were given at a mean frequency of 1,133 Hz (95 SD) and a rate of 117.7 calls/min (30.2 SD) and had a duration of 0.125 s (0.020 SD) with an inter-note interval of 0.416 s (0.140 SD) (n = 7 individuals, 280 calls).
Advertising call given almost entirely by males, but females produce a version during courtship. Barb (1995) observed a female giving the advertising call from inside a nest box on 19 April 1994 at 7:45 EST. Female version of advertisement call similar to that of male but softer and less consistent in pitch and amplitude (K. McKeever pers. comm., Cannings 1993).
Frequency of the advertisement call notes varies significantly and explains most variation among males (F4,41 = 8.04, P < 0.001; R2 = 0.93). This allows accurate identification of individuals using sonographic analysis of recordings (in addition to location of the calling owl; Otter 1996). Individuality of the advertisement call was maintained between nights with 86.4% of the variation attributable to between individuals and 2.8% between nights (Otter 1996).
The whistled notes of the male advertisement call of brooksi were 0.113 s (0.01 SD, n = 26) given at a frequency of 1194 Hz (47.2 SD, n = 26) and a rate of 2 or 3 /s (Holschuh 2004). Notes of the female and male advertisement call of brooksi are similar except that the females' are given at higher and less constant frequencies and have been described as having a more 'barky' quality (Holschuh 2004). The variance in the advertisement calls among males allows for the correct ascription of identity to individuals 74% of the time when multiple recordings were analyzed (Holschuh 2004).
...
Ksew call: Highly variable, rapidly repeated in single or multiple bouts (mean calls/bout: S.D. = 4.7 3.3; n = 20 bouts, 20 individuals; 11 of 20 owls gave three or fewer) of short, high-frequency notes with harmonic overtones (Hill 1995). Described as a harsh and startlingly loud staccato high-pitched bark (Hill 1995), duration of 0.095 s (0.044 SD), note duration of 0.073 (0.058 SD), internote interval of 0.055 (0.096 SD), frequency of 2652 Hz (1871 SD), and uttered at 1.5 notes/min (n = 20 individuals, 20 calls). Calls start at 1300 Hz, decrease to 1000 Hz and are 0.1 s long in brooksi (Holschuh 2004). Brewster (in Bent 1938) describes this call as resembling "…the sounds produced by filing a large mill saw...". Holschuh (2004) suggests this call is given when an owl is agitated by an intruder (or playback).
...
Tssst call: A distinctive high-frequency call usually composed of two harmonically unrelated whistles that differ in frequency by 100-1000 Hz uttered in bouts and at a rate of 1 call every 4-5 s (Hill 1995; see Fig. 3c). Given only by females in pre-copulatory dueting with males performing the rapid call and when males deliver food to the nest (Cannings 1993, Holschuh 2004). The Tssst call of brooksi females has a frequency of 9500 Hz, is 0.3 s, repeated every 1-2 s (Holschuh 2004). Tssst call of acadicus females is 0.203 s (0.039 SD) with a frequency of 8511 Hz (392 SD) (n = 9 individuals, 161 calls). The Tssst call has also been referred to as the "seet" call by Hill (1995). The "soft swee notes with rising inflection" described by Johnsgard (1988) possibly refer to this call.
...
Squeaks: Short calls with harmonic qualities described as an insect-like buzz by Collins (1993). In brooksi, this call has a two-note component given over 0.3 s; the first note is higher than the second (Holschuh 2004). May function as a threat display as uttered at very close range while flying by or attacking an intruder (Collins 1993, Holschuh 2004).
...
Transition call: As of yet, this call has been recorded only in brooksi (Holschuh 2004). Notes increase in duration (i.e., from 0.17 s through a calling bought) and frequency (i.e., from 1200 Hz to 1500 Hz through the duration of each note) and are repeated at a rate of 1 to 2 note/s (Holschuh 2004). Is uttered by highly agitated males between calling bout and series of whines (Holschuh 2004).
Alternate whine: As of yet, this call has only been recorded in brooksi: 1500 Hz, 0.4 s duration, and is often repeated for several minutes (Holschuh 2004). Used by agitated males at the end of an advertisement calling bout; sometimes used by males in response to playback (Holschuh 2004).
...
References
...
Holschuh, C. 2004. Monitoring habitat quality and condition of Queen Charlotte Saw-whet Owls (Aegolius acadicus brooksi) using vocal individuality. Ph.D. dissertation, University of Northern British Columbia.

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Old Friday 24th January 2014, 16:17   #15
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for people who know more about vocalizations, are the differences reported here significant?
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Old Friday 24th January 2014, 18:22   #16
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Quote:
Originally Posted by Mysticete View Post
for people who know more about vocalizations, are the differences reported here significant?
Well, no one seems to have hurried since 2004 to suggest that Holschuh's vocalisation data (alone) could potentially support the treatment of brooksi as a distinct species...

Last edited by Richard Klim : Saturday 25th January 2014 at 14:10.
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Old Friday 24th January 2014, 23:22   #17
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Reading Richards quotes, I (who probably am more pro than contra splitting) does not think this is good enough. A reanalysis of all recordings performed by one/the same author(s) and preferably trying to ensure that the recordings are equivalent in meaning by making new ones might change that.

Having said that, I am not a sound analysis expert!!!

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Old Friday 12th April 2019, 19:13   #18
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Kevin Winker, Travis C Glenn, Jack Withrow, Spencer G Sealy, Brant C Faircloth, Speciation despite gene flow in two owls (Aegolius ssp.): Evidence from 2,517 ultraconserved element loci, The Auk: Ornithological Advances, , ukz012, https://doi.org/10.1093/auk/ukz012

Abstract:

New study systems and tools are needed to understand how divergence and speciation occur between lineages with gene flow. Migratory birds often exhibit divergence despite seasonal migration, which brings populations into contact with one another. We studied divergence between 2 subspecies of Northern Saw-whet Owl (Aegolius acadicus), in which a sedentary population on the islands of Haida Gwaii, British Columbia (A. a. brooksi), exists in the presence of the other form (A. a. acadicus) during migration but not during the breeding season. Prior research showed fixed mtDNA divergence but left open the question of nuclear gene flow. We used 2,517 ultraconserved element loci to examine the demographic history of this young taxon pair. Although we did not observe fixed single nucleotide polymorphism differences between populations among our genotyped individuals, 100% of the birds were diagnosable and δaδI analyses suggested the demographic model best fitting the data was one of split-bidirectional-migration (i.e. speciation with gene flow). We dated the split between brooksi and acadicus to ~278 Kya, and our analyses suggested gene flow between groups was skewed, with ~0.7 individuals per generation coming from acadicus into brooksi and ~4.4 going the opposite direction. Coupled with an absence of evidence of phenotypic hybrids and the birds’ natural history, these data suggest brooksi may be a young biological species arising despite historic gene flow.
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Old Tuesday 28th May 2019, 17:02   #19
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Here is a blog post on the Avian Hybrids blog about the the paper that Peter posted about in the previous post on this thread.

Genomic analyses point to speciation with gene flow in the Northern Saw-whet Owl
https://avianhybrids.wordpress.com/2...-saw-whet-owl/
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