Mountain Plover
( Anarhynchus montanus )
The Status and Occurrence of Mountain Plover (Anarhynchus montanus) in British Columbia. By Rick Toochin. Revised: June 15, 2023.
Introduction and Distribution
The Mountain Plover (Anarhynchus montanus) is a medium sized shorebird that is found in western North America. In Canada, this is an Endangered Species with only a handful of birds found at Lost River, Wild Horse, and Milk River in southeastern Alberta, and very few birds found in Grasslands National Park in southwestern Saskatchewan (COSEWIC 2009). The maximum number of breeding individual Mountain Plovers recorded in Canada within one year has been eleven (COSEWIC 2009). The maximum number of nests found within one year has been six (COSEWIC 2009). There are several years where no plovers are reported and, indeed, they may not breed in Canada every year (COSEWIC 2009). The Mountain Plover is threatened by continuing conversion of native grasslands to croplands, agricultural practices and the management of domestic livestock in both Canada and the United States (COSEWIC 2009). Populations in the United States suffered greatly in the 1800s and early 1900s because of the uncontrolled trade in market hunting (COSEWIC 2009). Recent declines are attributed to the conversion of native grassland to cropland, agricultural practices, and the management of domestic livestock on both the breeding and wintering grounds (COSEWIC 2009). The decline of native herbivorous mammals, such as bison and prairie dogs, has led to detrimental changes in the remaining prairie ecosystems; indeed, in many of its breeding strongholds, Mountain Plovers are closely associated with prairie dog towns (COSEWIC 2009). The current global population is estimated to number between 9,000 to 19,000 individuals, with a decreasing population trend (O’Brien et al. 2006, COSEWIC 2009). In the United States, the Mountain Plover breeds from eastern-central and southwestern Montana (Bergeron et al. 1992), the tablelands of Wyoming (Oakleaf et al. 1992), and the eastern plains in Colorado (Andrews and Righter 1992) with isolated populations in other areas of Colorado (Knopf and Wunder 2006). There have been a few recent breeding records in Utah, northeast and locally to west-central and north-central New Mexico, south to the Roswell area and west to the Fence Lake area (Hubbard 1978). It was formerly found in Nebraska and was widespread in western and central Kansas (Goss 1891), but today has patchy breeding populations in Kansas (Knopf and Wunder 2006). It was also formerly found in western South Dakota (Knopf and Wunder 2006) This species is still found in the panhandle of Oklahoma and in the Texas Panhandle with an isolated breeding population found in the Davis Mountains of Texas (Knopf and Wunder 2006). There is a breeding population found in Mexico at Nuevo Leon (Knopf and Wunder 2006).
The Mountain Plover disperses widely across the western and southern Great Plains in the late summer and early fall (Knopf and Wunder 2006). The bulk of the population winters from north-central California to the Mexico border, primarily in the Sacramento, San Joaquin, and Imperial Valleys with some birds present west of the Coast Range in southern countries (Knopf and Wunder 2006). The winter distribution of the Mountain Plover is poorly known outside of California (Knopf and Wunder 2006). There are some birds periodically seen in Baja California, but the actual status there is still uncertain (Wilbur 1987). The Mountain Plover is known to winter in the Lower Colorado River Valley and from the Yuma to Phoenix and Chandler area south in Arizona (Monson and Phillips 1981, Rosenberg et al. 1991). The Mountain Plover is also found in Texas (Oberholser 1974), being a regular winter resident in Williamson (Fennell 2002) and Hudspeth Counties with small flocks reported each winter across southern Texas, and a sporadic winter visitor to Florida (Robertson and Woolfenden 1992). The Mountain Plover is also reported in the winter in Mexico, south to the Sonora in the west (Russell and Lamm 1978); Tamaulipas in the east; and Nuevo Leon, San Luis Potosi, and Zacatecas in the interior (Howell and Webb 2010); however, distribution in Mexico is poorly known (Knopf and Wunder 2006).
The Mountain Plover is an accidental vagrant anywhere in North America away from its breeding range and wintering grounds (Knopf and Wunder 2006). Along the West Coast In Oregon, there are at least 10 accepted records by Oregon Bird Records Committee and all these records are from the late fall and winter months (OFO 2012). In Washington State, there are 5 accepted records by the Washington Bird Records Committee of which 4 are from the winter months and 1 from the month of May (Wahl et al. 2005, WBRC 2014). The Mountain Plover is an accidental species in the fall in British Columbia. There are no records for Alaska or the Yukon (Gibson et al. 2013, Sinclair et al. 2003).
Identification and Similar Species
The identification of the Mountain Plover is covered in all standard North American field guides. This species is a medium to larger sized plover measuring 23 cm (9 inches) in length with a wingspan of (23 inches), and weighing 105 grams (3.7 ounces). This species is a little smaller than a Killdeer (Charadrius vocierus) which measure 26cm (10.5 inches) with a wingspan of 61 cm (24 inches), and weighs 95 grams (3.3 ounces). The Mountain Plover differs from Killdeer by having longer legs and a more erect posture, more closely resembling the larger American Golden Plover (Pluvialis dominica) which measures 26cm (10.5 inches) with a wingspan of 66 cm (26 inches), and weighs 145 grams (5 ounces). The sexes of Mountain Plover are similar in size and overall plumage colouration (Knopf and Wunder 2006). This is a drably coloured species most of the year, lacking the obvious black breast bands typically found on many other plover species found in North America (Dunn and Alderfer 2011).
Breeding plumage is held from March to August (Sibley 20030. The upperparts are a fairly uniform sandy-brown with this colouration extending alongside of the neck, ear-coverts, and onto the chest (Dunn and Alderfer 2011). The forecrown is mottled black to solid black (Hayman et al. 1986). On the face is a long white supercilium that extends past the dark eyes towards the nape (Message and Taylor 2005). The forehead, throat, and breast are white, but some adult birds show rufous on the sides (Hayman et al. 1986). On the face, there is a thin black line extending from the eye to the base of the long, thin dark bill (Sibley 2000). In flight the underwings are bright white (Hayman et al. 1986). The upper wing in flight has dark primaries with a distinct white patch in the primary shafts (Sibley 2000). The rest of the upper surface of the wing is sand-brown (Sibley 2000).
Adult winter plumage is held from August to March (Sibley 2000). Winter-plumaged adults are similar looking to breeding plumage adults with the following exceptions: the black on the crown and the lores is replaced by pale-brown; the ear-coverts are slightly browner with the upperparts having somewhat more extensive dull rufous fringes, and the patches on the sides of the breast are buffier and cover a more extensive area (Hayman et al. 1986).
Juvenile plumage is held from August to October (Sibley 2000). Juvenile birds are similar looking to winter-plumaged adults, but the feathers of the upperparts are slightly darker brown with larger, brighter buff fringes giving these birds a more clearly scaly appearance (Message and Taylor 2005). The crown is less dark, appearing speckled or finely striped with a buffy supercilium that is not white like adult birds (Dunn and Alderfer 2011). The sides of the breast are flecked with darkish-brown (Hayman et al. 1986).
The Mountain Plover has a unique plumage colouration that is not easily confused with that of any other shorebird usually within its normal range (Hayman et al. 1986). This is the only North American plover species with a black frontal bar on the forecrown and a clear white breast (Hayman et al. 1986). The only potentially similar looking species to the Mountain Plover is the winter-plumaged Lesser Sand-Plover (Charadrius mongolus) which is a rare vagrant in North America and British Columbia, and is much darker with a distinctly larger bill (Hayman et al. 1986).
The flight call is a coarse “grrrt” or a lower single note “dirp”, similar to the call of a Western Meadowlark (Sturnella neglecta) (Sibley 2000). The Mountain Plover also gives a coarse gratting “ji ji ji ji ji” (Sibley 2000).
Occurrence and Documentation
The Mountain Plover is an accidental vagrant to British Columbia with only one record of a juvenile bird found by Mike Toochin, Mark Wynja, and Rick Toochin in a field along Trim Road on Westham Island in Ladner on September 28, 1986 (Campbell et al. 2001, Toochin et al. 2014). This bird was in a mixed flock of 30 Black-bellied Plover (Pluvialis squatarola), 2 juvenile American Golden Plover and a lone winter-plumaged Dunlin (Calidris alpina) (R. Toochin Pers. Comm.). The bird was well observed through binoculars and telescopes both in flight and sitting on the ground amongst the other birds at a range of 200 to 400 feet (R. Toochin Pers. Obs). This represents the only record of this species for British Columbia. In Paulson (1993), there is a monthly graph showing when Mountain Plovers have occurred in the Pacific Northwest region with a graph showing the peak time of their occurrence in western parts of Montana and Idaho. There is a thin line shown for the last week of September and the first week of October, exactly when the bird in Ladner was found (Paulson 1993, Toochin et al. 2014). The overall occurrence pattern is along the west coast in Washington and Oregon where the Mountain Plover is a review species; and this species is a winter visitor with dates that range from November 19 to March 10 (Paulson 1993). The habitat where these birds have been found on the coastlines of Oregon and Washington is flat, open sandy beaches (Paulson 1993, Knopf and Wunder 2006). A recent winter record from South Beach State Park in Lincoln County, Oregon from December 4, 2015 – March 22, 2016 had a Mountain Plover wintering in the same area as a Snowy Plover (e-bird database). The fact this species is declining over its entire breeding range makes the overall likelihood extremely low of any birds turning up in British Columbia in the future.
Acknowledgements
I wish to thank Barb McKee for editing the manuscript.
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