OCCURRENCE OF SNOWY AND COLLARED IN THE INTERIOR OF MEXICO

STEVE N. G. HOWELL and SOPHIE WEBB, Point ReyesBird Observatory,4990 ShorelineHighway, Stinson Beach, 94970

The A.O.U. (1983) noted breedingby Snowy Plovers( alexandrinus) in the interior of North America south to southernArizona and southernNew Mexico;all recordsfor Mexico (breedingand winter) were coastal.The Collared (Charadrius collaris) is describedas residentfrom Sinaloaand Veracruzsouth through Middle America, prima- rily in coastalareas (A.O.U. 1983, Friedmannet al. 1950). We detailhere severalrecent records(since 1982) of both of these ploversfrom the interior of northern and central Mexico. Our hope is to make observers awareof the potentialoccurrence of Snowyand Collared plovers at sitesin the interiorof Mexico.Figure I showssites mentioned for SnowyPlovers in the followingaccounts.

SNOWY PLOVER

Coahuila

At Presa El Tulillo (25ø40' N, 101ø24 ' W; elevation 1100 m), a reservoir 50 km west-northwestof Saltillo,we noted four to five basic-plumaged SnowyPlovers along the southshore on 27 November1986. Aldegundo Garzade Leon (pers.comm.), an ornithologistresident in Saltillo,collected two SnowyPlovers (numbers 778 and 779 in hiscollection) at El Tulilloon 21 March 1982, but has found no evidencethat the speciesnests at this site.

Zacatecas At PresaAcecatecana (22ø44 ' N, 102ø33' W; 2150 m), a largereservoir southof the bypasson the southside of the city of Zacatecas,we found 11 or 12 alternate-plumagedSnowy Plovers on 27 June 1991 in an extensive dry muddyarea alongthe reservoir'snortheast corner, near the dam. The includedthree or four apparent pairs, which gave the upslurred chuweepand low perrt callstypical of nestingbirds. We saw one apparentlytrying to leadanother into a smallarea where the firstbird would sit down as if in a nest scrape;however, we found no eggs.Howell visited this reservoiron 4 January1984 and 12 April 1987 but saw no Snowy Plovers on those dates. To our knowledge,the only previousreport from Zacatecasis of three seen,and an adultfemale collected,at a shallowlake 8 km eastof Noria de losAngeles in the southeastof the state,3 August1959 (Webster1968); this site is 25 km due south of Salinasde Hidalgo, San Luis Potosi (see following). 146 WesternBirds 25:146-150, 1994 SNOWY AND COLLARED PLOVERS IN MEXICO

San Luis Potosi

On 28 June 1991, immediatelywest of the town of Salinasde Hidalgo, in western San Luis Potosi (22038 ' N, 101045 ' W; 2100 m), we saw six to eightpairs of SnowyPlovers, including an adultwith two smallchicks, at the largestlagoon south of Highway49. We have foundno previousrecords from San Luis Potosi.

Ouanajuato At the smallreservoir southwest of Highway 111, 5 km eastof Dolores Hidalgo(21008 ' N, 100053' W; 1900 m), P. Pyle and Howell saw a single basic-plumagedSnowy Plover on 6 January1984. We havefound no other recordsof the speciesfrom Guanajuato.

I !

ß Breeding (confirmedand probable) ß Migrant (Aug-Dec) ß Migrant(Jan-Apr)

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Figure1. CentralMexico, showing sites in the interiorwhere SnowyPlovers have been recorded.1, PresaEl Tulillo,Coahuila; 2, PresaAcecatecana, Zacatecas; 3, Salinasde Hidalgo,San LuisPotosi; 4, Noriade losAngeles, Zacatecas; 5, Dolores Hidalgo,Guanajuato; 6, Atoyac,Jalisco; 7, San Gregorio/Tlahuac,Distrito Federal; 8, LagoTexcoco, M•xico; 9, LagunaTotolcingo, Puebla. 147 SNOWY AND COLLARED PLOVERS IN MEXICO

Jalisco On 9 March 1992, Howell found six alternate-plumagedbirds at the permanentlake immediately northeast of Highway54D at kilometerpost 33 (20ø08' N, 103ø33' W; 1500 m), near Atoyac.The birdsincluded one apparentpair, and Howell heard a few chuweepcalls being given. At the muchlarger shallow seasonal lake east of highway54D betweenkilometer posts35 and40, Howellnoted at least100 SnowyPlovers on 27 February 1993; none showedany indicationsof nesting.We knowof no previous records from Jalisco.

Puebla LagunaTotolcingo, a vastshallow lake, straddles the easternborder of Tlaxcala with the state of Puebla (19ø20' N, 97ø62 ' W; 2200 m). On 12 December1986 we saw 100+ SnowyPlovers on the extensivesalt fiats borderingthe lake north of Highway136, all apparentlyin the stateof Puebla.At least 40% of the birdswere in full alternateplumage, 20% or more were in basicplumage, and 30% of the birdswere juveniles, some in veryfresh plumage; the remainderwere too distantfor theirplumage to be assessedaccurately. We havefound no otherrecords from Puebla. Howell visitedthis lake on 21 January1984 but sawno SnowyPlovers. The large expanseof the lakeand salt flats, however, combined with fluctuating water levels,means that at any giventime muchof the area may be generally inaccessibleto observersand/or unsuitablefor plovers. M•xico/Distrito Federal The onlyrecords of the SnowyPlover from the DistritoFederal are of singlealternate-plurnaged birds seen at therelatively heavily birded marshes on the southside of MexicoCity (19ø16' N, 99ø08' W; 2200 m), at San GregorioAtlapulco on 22 April 1985 (Wilsonand Ceballos-L. 1986), and at Tlahuacon 22 April 1992 (Howelland R. G. Wilson).Snowy Plovers occurin summerand maynest at LagoTexcoco (19ø30 ' N, 99ø02'W) on the Mexico/D.E border(wilson and Ceballos-L.1986, R. G. Wilsonpers. comm.).

COLLARED PLOVER

CollaredPlovers are residentlocally along rivers in the lowlandson both coastalslopes of Mexico,and we haveseen them up to 250 km from the coast(e.g., at Yaxchilan,Chiapas). Such records,however, are all in the tropicallowlands (below 500 m elevation).Records that fall outsidethis patternare listedbelow. Jalisco At the extensivemarshes and lakesbeside Highway 54D northof Sayula (20o02' N, 103o34' W; 1500 m), we saw five CollaredPlovers, including two apparentpairs, on 31 March1988, andHowell noted four birds on 10 March 1989 and four on 27 February1993. 148 SNOWY AND COLLARED PLOVERS IN MEXICO

Tlaxcala

On 21 January1984, P. Pyle and Howell founda CollaredPlover at a small pool in the short-grassplains borderingLaguna Totolcingo,in Tlaxcala.They realizedthe rarityof suchan occurrenceand carefullynoted the bird'selegant, slender build and slender,all-black bill. Other features notedwere the bold,clean-cut white foreheadpatch, the complete,narrow black chest band, a rufouswash to the sidesof the head, lack of a white hindcollar,and the slender,pale flesh-colored legs. This is the onlyrecord of CollaredPlover we are aware of from the Mexicanplateau. Morelos

At LagunaE1 Rodeo (18046 ' N, 99020' W; 1000 m), a smallnatural lake 15 km south-southwestof Cuernavaca,R. G. Wilson (pers. comm.) re- cordedup to four CollaredPlovers in the wintersof 1983/1984 (alsoseen by Howell and P. Pyle), 1986/1987, and 1989/1990, with extremedates of 8 Octoberand 15 March. We saw none at El Rodeo on 20 May 1990, and R. G. Wilson (pers.comm.) has seen none there duringseveral visits from April to September. Guerrero

At Lagunade Tuxpan(18022 ' N, 99030' W; 750 m), a large lake 2 km eastof Iguala,we and R. G. Wilsonsaw three to five CollaredPlovers along the southshore on 16 December 1986. We saw none there on 20 May 1990 or 2 June 1986.

DISCUSSION

Theseobservations indicate that SnowyPlovers breed locally in summer at lakesand reservoirson the Mexicanplateau. While our onlycertain proof of nestingwas the chicksin San LuisPotosi, the callsand behaviorof the birdsin Jaliscoand Zacatecasstrongly suggest that they alsowere nesting. The speciesalso may nest at LagoTexcoco, state of M•xico. By December, many winteringSnowy Plovershave attainedalternate plumage(G. W. Page pers. comm.), which may explain our observation at Laguna Totolcingo.The numberof fresh-plumagedjuveniles there, however,may alsosuggest late summernesting by SnowyPlovers at or near the site. NonbreedingSnowy Plovers, possibly from the interiorof NorthAmerica, occur as winter migrantsto the Mexican plateau, with specificrecords between November and March. The two April records, both from the DistritoFederal, may representmigrants headed for nestingsites in Mexico, sincemost Snowy Plovers nesting in the interiorand on the Pacificcoast of the U.S. have by then arrivedat breedingareas (G. W. Page pers. comm.). Clearly, more field work is needed to determinethe nestingseason, distribution,and breedingand winter abundanceof Snowy Ploversin the interior of Mexico; for example, numerouslarge shallowlakes on the Mexicanplateau in the statesof Chihuahuaand Durangohave never been surveyedfor Snowy Plovers.The dearth of recordsfor both Snowy and Collaredplovers from the interiorof Mexico prior to the 1980s probably 149 SNOWY AND COLLARED PLOVERS IN MEXICO reflectsa lack of observercoverage rather than range expansionby either species. The CollaredPlover appears to be a winter visitor(October to March)to lakesin the Rio Balsasdrainage of interiorsouthwest Mexico and a winter vagrantto the centralhighlands (the January record from Tlaxcala). There is no evidenceof breedingby CollaredPlovers at the lakesin Guerreroand Morelos. Although Widrig (1983) reported Collared Plovers nesting in Decemberin coastalNayarit, other known nestingdates from southwest coastaland interior Mexico are in spring: on 11 April 1988 at Puente Mexcalhuacan,Michoacan, we found an agitatedpair of CollaredPlovers behavingas if they had chicksnearby; on 20 May 1990 (whenwe sawno CollaredPlovers at either El Rodeo or Tuxpan)we founda nestwith four eggson the beachat the easternend of LagunaMitla, Guerrero;Binford (1989) saw an adult with three chicksin coastalOaxaca, 19 April 1964; Amadon and Eckelberry(1955) saw adultswith chicksat two sites in interior southeasternVeracruz and western Chiapas in mid May 1952. Further work is needed to determine this species'status in southeastern Jalisco.

ACKNOWLEDGMENTS

We thank RichardG. Wilson for communicatinghis unpublishedrecords, and LaurenceC. Binford,Gary W. Page,and StephenM. Russellfor their carefulreview of the manuscript.This is contributionnumber 599 of PointReyes Bird Observatory.

LITERATURE CITED

Amadon, D., and Eckelberry,D. R. 1955. Observationson Mexicanbirds. Condor 57:65-80. AmericanOrnithologists' Union. 1983. Check-listof North AmericanBirds, 6th ed. Am. Ornithol. Union, Washington,D.C. Binford,L. C. 1989. A distributionalsurvey of the birdsof the Mexicanstate of Oaxaca.Ornithol. Monogr.43. Friedmann,H., Griscom,L., and Moore, R. T. 1950. Distributionalcheck-list of the birdsof Mexico,part 1. Pac. CoastAvifauna 29. Webster,J. D. 1968. Ornithologicalnotes from Zacatecas,Mexico. Condor 70:395- 397. Widrig, R. S. 1983. Decembernesting of the CollaredPlover in west Mexico.Am. Birds 37:273-274. Wilson, R. G., and Ceballos-Lascurain,H. 1986. The Birdsof Mexico City. BBC Printingand Graphics,Burlington, Ontario.

Accepted 28 February 1994

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