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New species of meadowlark distinguished: Is it present in Oklahoma????

In the recent 2022 Supplement update of the Checklist of North American Birds, the American Ornithological Society split off and recognized Chihuahuan Meadowlark (now Sturnella lilianae) as a species separate from Eastern Meadowlark (Sturnella magna). The Chihuahuan Meadowlark is a combination of two former subspecies of the Eastern Meadowlark, lilianae, that nests primarily in New Mexico, Arizona, the Trans Pecos of Texas and adjacent northern Mexico, and auropectoralis, that occurs further south in western Mexico (see Figure below).

Figure caption. Sturnella range map showing the ranges for Western Meadowlark (S. neglecta) and the subspecies of Eastern Meadowlark (S. magna). The subspecies S. m. lilianae and S. m. auropectoralis are now recognized as the Chihuahuan Meadowlark. Image from Beam, J. K., Funk E. R., Taylor, S. A. (2021). Genomic and acoustic differences separate Lilian’s Meadowlark (Sturnella magna lilianae) from Eastern (S. magna) and Western (S. neglecta) meadowlarks. Ornithology 138:1-13.


Johanna Beam conducted the work supporting the split as an undergraduate research project at the University of Colorado. She analyzed song patterns and whole genome sequencing of the meadowlark complex. The Chihuahuan Meadowlark sings a song similar in general pattern to that of an Eastern Meadowlark but distinct in quality of notes and presentation (see https://media.ebird.org/catalog?taxonCode=lilmea2&mediaType=audio for a listen). Phylogenetic analysis distinguish Chihuahuans as a distinct clade from Western and other Eastern meadowlarks. The study was published in Ornithology journal (Beam et al. 2021; cited in figure caption) https://academic.oup.com/auk/article/138/2/ukab004/6249548 (may only be available to AOS members or for a fee).


What about Oklahoma?

Meadowlarks have an interesting distribution pattern in Oklahoma. For breeding, the shift from predominantly Eastern to predominantly Western meadowlarks occurs in west-central Oklahoma, but is an intermixed patchwork influenced by habitat. More westerly, Western Meadowlarks occur on the drier uplands and shorter grasslands. Easterns penetrating westward mostly occupy taller un-grazed habitat that occurs largely in wetter lowland areas. For example, Easterns dominate managed taller grasslands in the Wichita Mountains WR and Hackberry Flat WMA in southwestern Oklahoma, but Westerns dominate more heavily grazed areas just outside the Refuge in western Comanche County, and areas in Tillman County outside Hackberry Flat.


How far west in Oklahoma do Eastern Meadowlarks occur during the breeding season? They are known to breed in taller lowland grasslands west to eastern Texas County in the Oklahoma Panhandle. This is contiguous with the southwesterly angled distribution pattern of breeding in Kansas west to Meade and Clark counties, due north of the eastern Oklahoma Panhandle. Birds breeding here are believed to be the subspecies magna of the Eastern Meadowlark as are the birds breeding in eastern Texas County.


Records of Eastern-type meadowlarks in Oklahoma westerly past eastern Texas County are scarce. This is true whether for the breeding season or other times of the year. Most records relevant to Oklahoma are focused on the Rita Blanca National Grassland in southern Cimarron County (at the very western edge of the Oklahoma Panhandle) and the very northwest corner of Texas. Because they were previously identified as Eastern Meadowlarks (before the split), they may represent Chihuahuan Meadowlarks. One record by Tony Leukering on 24 July 2017 northwest of Keyes, Cimarron County was tentatively accepted as lilianae in eBird based on photos of tail pattern (see below).


Of note are several reported records of potential Chihuahuan Meadowlarks in Colorado, in Baca County (southwestern CO) and on the High Plains along the Front Range north to the Longmont area, Boulder County. The latter was of a meadowlark discovered by Johanna Beam that inspired her undergraduate research project. Colorado Birds provided an information announcement (see https://cobirds.org/new-meadowlark-species-chihuahuan-meadowlark-includes-the-lilians-subspecies/ ). As with the Colorado Bird Records Committee, evaluation of the potential records so far accumulated in Oklahoma will be made by the Oklahoma Bird Records Committee (OBRC). So, it is important to record and submit details of any records, already obtained or in the future, through eBird, or directly to the OBRC.


HOW CAN CHIHUAHUAN MEADOWLARKS BE IDENTIFIED?

The study by Beam et al. (2021) showed the song of Chihuahuan Meadowlarks to be distinctive from both Eastern and Western meadowlarks. The pattern of Chihuahuans is simpler and less sweet than an Eastern-type song. Examples can be found in eBird from New Mexico and Arizona, with a caveat that some meadowlarks can learn other species’ songs (fide Nathan Pieplow). Nonetheless, clear recordings of the song would be most useful in documentation.


There are differences in plumage, but they are more subtle, can be subjective and may need to be clarified. In general, Chihuahuans appear to be similar to Western Meadowlarks, paler and with more-spaced bars on coverts and secondaries, but with an Eastern-type head pattern (with the malar being separately pale from the yellow throat). Beam et al. (2021) comment that Chihuahuan Meadowlarks have a paler mantle, brown vs. black head coloration, smaller black chest stripe, and lesser extent of yellow in the belly than in Easterns of magna. The Easterns of magna in Oklahoma have darker back feathers with more solid spotting (feather centers). The white in the outer-tail feathers is clearly more extensive in Chihuahuan than in Western Meadowlarks, but not necessarily so from all Easterns, thus requiring some further investigation. As these are investigated more closely, some additional clarity can be added, but are points to note in potential identification.

Figures of Western Meadowlark (left), Chihuahuan Meadowlark (middle) and Eastern Meadowlark (right). Note yellow on malar in Western, but not Chihuahuan and Eastern. Note thin bars on secondaries and coverts of Western and Chihuahuan, but broader bars in Eastern. Chihuahuan is more lightly streaked on the flanks. Photo credits: Western Meadowlark (Joe Grzybowski), Chihuahuan Meadowlark (Alan Schmierer), Eastern Meadowlark (Jim Arterburn).


For your information as a service of the Oklahoma Ornithological Society. If not a member, join today.

Joe Grzybowski 2 September 2022

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