CaveSwallow range continues to expand

Cliff and Barn swallows may be displaced from their former nesting sites by the continued expansion of the Cave Swallow

Paul C. Palmer

Swallows was noted in American Birds Nancy and I set out in the afternoon to tin and many others have docu- in 1984 not only in Jim Hogg, Brooks, test that hypothesis.Within two hours INCEmentedTHE a phenomenalEARLY 1970S, expansion R.F.MAR-of and Duval counties,but in Kleberg,one we found mixed breeding coloniesof the rangeof the Cave Swallow(Hirundo of the counties of the Texas Coastal Barn and Cave swallows at five locations fulva) in Texas. That range expansion Bend. Steve Labuda of Santa Ana Na- along US 77 in Kleberg and Kenedy hasbeen accompaniedby a pronounced tional Wildlife Refuge discoveredand counties. breakdownof the former segregationof ThomasPincelli reporteda nestingcol- US 77 is the only north-south h•gh- the speciesfrom othersof its genus;most ony, including all three species,under a way through thosecounties. The swal- of the new nesting colonies have in- concrete bridge on SH 285 at Salado low colonies were located under con- cludedBarn Swallows(Hirundo rustica) Creek, west of Riviera in southernKle- crete bridgesalong the highwayand •n and many have included Cliff Swallows berg County (Lasley and Sexton 1984; concrete culverts under it. One of the (H irundopyrrhonota ) (Oberholser1974; Pincelli per& comm.). Cave Swallows sites was at Ebanito Creek, 3.5 kdo- Martin 1974; Martin and Martin 1978; returned to that site in 1985 and 1986, meters south of Ricardo. Another was Kutac 1982). The new nestingsites have despite destruction of the original 8.75 kilometers south of Ricardo. The been concretehighway bridges and cul- bridge. By summer 1985, Richard Al- smallestwas at the largestbridge, cross- verts. It hasbeen shownclearly that hy- bert, Charles Clark, and others had re- ing Los Olmos Creek, the Kleberg- bridization has occurred at some of ported nesting colonies in two other Kenedycounty line. The fourth sitewas thosesites (Martin 1980). Texas Coastal Bend counties, San Pa- 4.2 kilometers south of Los Olmos By 1978 the range expansionof the tricio and Jim Wells(Lasley and Sexton Creek at culvertswhich servefor moving Cave Swallow had extended southward 1985). livestockbetween pastures east and west and eastward to include Atascosa and On April 27, 1986, my wife, Nancy, of the divided highway.The fifth was Duval counties, probably Live Oak and I found Cave Swallows at nests un- under a bridge over another cattle run County, and possibly Jim Hogg and der a concretebridge on SH 141 at Santa 2.8 kilometers south of Sarita, the Bexar counties (Martin and Martin Gertrudis Creek eight kilometerswest county seatof Kenedy County. 1978). This expansionwas speedier than of Kingsville, Kleberg County. While On May 16, 1986, we discovereda the printers of Texas A and M Univer- talking about the discoverywith John small mixed colony including at least sity Press. By the time Rappole and Rappoleof the CaesarKleberg Wildlife one pair of adult Cave Swallowson the Blacklock'sexcellent Birds of the Texas ResearchInstitute and Mark Kopeny, a nest within the Kingsville city limits, CoastalBend (1985) appeared,showing graduatestudent from North Dakota in where US Bus 77 crosses Escond•do the Cave Swallowas hypotheticalfor the southTexas studying the breedingecol- Creek. By May 18,a secondpair of Cave tone counties covered,the specieshad ogy of White-tailed Hawks, I ventured Swallowswas presentat that site. already been fully documentedin some the not-entirely-idlespeculation that the May 19, 1986, I found two colomes of those counties. Cave Swallows might very well have including Cave Swallows in Nueces The presence of colonies of Cave reached US 77. On May 12, 1986, County: under a concretebridge on US

174 American Birds,Summer 1988 77 1 5 kilometersnorth of Dnscoll, and prewous breeding seasons. Of the nesthngswere probablehybrids, hawng •n B•shopwhere US Bus 77 crossesCar- roughly200 b•rdspresent, 110-120 ap- chestnut foreheads, forked tatIs w•th reta Creek. Reports of a Cave Swallow peared to be Cave Swallows, with the white spots, and cinnamon rumps. colonyon US Bus 77 in Sinton, San Pa- rest being Barn Swallows. Martin's (1980) researchhas shownthat tncio County, proved to be mistaken; There were approximately 80 nests those young that look like hybrids that site was occupied exclusivelyby at the site 4.2 kilometers south of Los probablyare hybrids.I was not able to Chff Swallows. Olmos Creek. Because of the cattle discover which adults were associated It canbe ratherdifficult to distinguish fencesit was not possiblefor us to ex- with the nest containingthe apparent Cave Swallows from Cliff Swallows un- amine them closely.About 60 percent hybrids. On May 18, numerousnests at less viewing conditions are excellent. of the more than 100 birds we observed that site had nestlings,others eggs, and Sorting out their nestsis lessof a prob- were Cave Swallows. The others were the nest which contained the apparent lem. A Cliff Swallow nest is almost al- Barn Swallows. We found no Cliff Swal- hybrids six days earlier was empty ways a recognizablegourd or bottle lows or nestsof that speciesat the site. Many youngwere present in the colony shape,bulbous with a narrow entrance. We were able to locate only five nests May 28. at the Los Olmos Creek site. None were Thesenests are placedat oddangles and We tried to find Cave Swallows •n are often attached to one another. In of the Cliff Swallowtype. One pair of nestingcolonies at severalplaces east of culvertsand underbridges they are usu- Cave Swallowswas flying about at the US 77 in Kleberg County. We found ally built at the intersectionof wall and southend of the bridge.All the remain- none, althoughBarn Swallowswere seen ceding(or vertical and cross-member) ing birds we identified were Barn Swal- at most suitablesites and a mixed group and are attached to both. Cave Swallow lows. of Cliff and Barn swallowswas present At the Ebanito Creek site there were nestsare shapedlike halfa cup,attached at one site. We could not explore Ken- to a wall. 19 nests;all were either Cave Swallow edy County east of US 77 due to lack Separating the Cave Swallow and or Barn Swallow types. Over 30 birds of access,but knew of no likely nesting Barn Swallow nests can be a bit more were observed; about one-half were sitesto examine in any case.It appears difficult,since both are half-cup-shaped. Cave Swallows and one-half Barn Swal- that US 77 marks the easternedge of There are useful but not absolute rules lows. the Cave Swallow breeding range as of of thumb to follow.Generally the Cave At the site 8.75 kilometers south of summer 1986, almost certainly in Kle- Swallowsbuild very closeto the ceiling Ricardo there were 14 nests,none of the berg County, and probably in Kenedy and usealmost nothing but mud in their Cliff Swallow type. We identified six and Nueces counties as well. neststructure, although they do line the Cave Swallows and 18 Barn Swallows. nestwith fiber.Barn Swallowsare likely There were no Cliff Swallowspresent. Thirty yearsago, R.K. Selanderand to build lower, leavingspace to fly in Not possessinga boat or raft, we J.K. Baker (1957) speculatedthat the and out of the nestseasily. They also could not get a reliable count of nests then severelylimited rangeof the Cave use much more plant and/or animal fi- at the EscondidoCreek site in Kings- Swallow in Texas might have resulted ber in building their nests,sometimes ville, despite the best efforts of our from failure in competition with Chff making them seem positivelyshaggy. friend, Sharon Bartels. There were no Swallowsfor nestingniches. Four years Cave Swallowstend to prefer a flared Cliff Swallownests among those we saw. of irregular observationsof the recent nm or lip on their nestsand often build At least one adult Cliff Swallow was rapid expansionof that rangehave cre- complete or partial sideswhich rise a present,however. Most of the birdswere ated in this observerthe strongimpres- few centimeters above the rim of the Barn Swallows;we counted four adult sionthat the Cliff Swallowis now losing cup, sometimesto the ceiling(Martin Cave Swallows. ground to the Cave Swallow. Possibly and Martin 1978;pets. obs.).Barn and At the site 1.5 kilometers north of the Barn Swallow is also being evicted Cave swallows also attach their nests to- Driscoll I found 13 nests,all of the forms from some of the nestingsites it once gether condominium-fashion at times characteristic of Cave and Barn swal- dominated. Gene Blacklock, Coordi- nator of Environmental Education for and don't always follow the "rules" lows. Of the 24-30 birds we saw there concerningnest shapeand placement. at least two were Cave Swallows; about the Welder Wildlife Foundation, shares When one becomesfairly adept at 10 were Barn Swallows.Light conditions that impression(Blacklock pers. comm ). sorting out the nest forms, it is occa- and distancemade it impossiblefor us Fragmentarydata gatheredfrom breed- sionallypossible to determineexactly to be certain of the others. ing bird surveysand additionalpersonal where one speciesbegan to remodel or We werenot ableto makeany reliable observationsmade in June and July build onto a nestoriginally constructed count of nestsor birdsat the Bishopsite. 1986 providesome evidence to support by another species.This can be very At least one pair of Cave Swallowswas the hypothesis. useful in trying to determine the se- presentalong with severalBarn Swal- BreedingBird Survey reports by An- quenceof habitationat a givensite and lows. drew O'Neil for the Randado route, was often helpful for this study. We examined two nests at the site which beginsin Jim Hogg and ends •n Efforts were made to estimate the westof Kingsville on May 3, 1986. One Duval County, show Cave Swallows numbersof birds of each speciesat the wasempty; the othercontained five eggs. presentat three stopsin May 1986. At s•teswe found. The largestcolony was On May 10, both Cave and Barn swal- Stop number 12 30 Cliff Swallowsand the onesouth of Sarita;it contained112 lows were incubating at that colony. eight Cave Swallowshad replaced the nests,all but 20 under the eastspan. A On May 12, we examined four nests Barn Swallowswhich exclusivelyoccu- few(four to six)were Cliff Swallownests, at the site south of Sarita. One was pied the site in 1984 and 1985. At Stop but we identified no Cliff Swallows at empty; two contained four eggseach; number 46, where four Cliff Swallows the site.The nestsmay havebeen from and one containedtwo nestlings.The had been counted in 1984, there were

Volume42, Number 2 175 ACKNOWLEDGMENTS

Update to Summer 1988 Thanks to Richard O. Albert, Gene W. Blacklock, Andrew W. O'Neil, and We found no Cave Swallownesting colonies east of US 77 in 1987, but in April 1988 Nancy and I found three suchsites, and SharonBarrels found a ThomasPincelli for generouslysharing their data and ideas. John S. West- fourth.Nancy and I foundanother in June.All werein FOebergCounty. All three specieswere presentat two of the locations,with Cliff Swallowsby far moreland and Craig S. Bartels assisted the least numerous. Barn Swallowsappeared to be the most numerous at all with transportation. Specialthanks are fivesites. The largestof the sitesis alsothe farthesteast and nearestsalt water; due Nancy B. Palmer and Sharon G. it is at a new bridgeover Radicha Creek on FM 772, approximately10 km Bartels. Both provided transportation east-southeast of Ricardo. and helped with observations.Nancy Various additional piecesof evidencesupport the hypothesisthat Cave lent her professionalskills to improve Swallowsare taking overniches formerly utilized by Barn and Cliff Swallows. my writing. Sharon put the draft 19 June 1987 we photographednests being used by Cave Swallowsat a throughher word processorand kept me McMullenCounty site; all saveo•ne of 43 nestsbeing used by themshowed humbleby beatingme at TrivialPursutt clearsigns of havingbeen built original!y by BarnSwallows. 13 March 1988 in ZavalaCounty Nancy and I foundand photographed a formerCliff Swallow nestingsite which had been converted into a CaveSwallow site. 14 May 1988, while conductingthe Randado route breeding bird survery,Andrew O'Neil found 175 Cave Swallowsat 13 stopsand only one Cliff Swallow.On his McMullen County BreedingBird Surveyin June 1988 Blacklockfound 107 Cave Swallows,6 Barn Swallowsand no Cliff Swallows. As of 28 May 1988 the swallownesting site under the US Bus 77 bridge in Sinton,San Patricio County, was still exclusively occupied by Cliff Swallows.

no Cliff Swallows and 26 Cave Swallows. their location on the culvert walls,were LITERATURE CITED No swallowsof any specieswere counted originally built by Barn Swallowsbut KUTAC, E. A. 1972.Texas birds: where they at the stop in 1985. At Stop number 50 had been remodeledby Cave Swallows. are and how to find them. Lone Star in 1984 there were 30 Cliff Swallows and Accordingto Blacklock (pers. comm.) Books, Houston. 28 Cave Swallows;in 1985 there were those sitescontained only Barn Swal- LASLEY, Greg W. and Chuck SEXTON six Cliff Swallowsand 30 Cave Swallows; lows and Cliff Swallows until recent 1984. The nesting season:South Texas m 1986 there were no Cliff Swallows and years.Not only have Cave Swallowsdis- Region. Am. Birds 38:1038-1040. 1985.The nestingseason: South Texas placed the other speciesat the sites,but 45 Cave Swallows.Only at Stopnumber Region. Am. Birds 39:933-936. 26 was the pattern reversed.Two Cliff, their numbershave increased markedly. MARTIN, R. E 1974.Syntopic culvert nest- ten Barn and six Cave swallows were A similar developmentseems to have ing of Cave and Barn Swallowsin Texas counted there in 1985; there were 12 occurredin Brooks County. On July 3, Auk 91:776-782. Cliff, six Barn and no Cave swallowsre- 1986, Andrew O'Neil, Nancy and I ob- 1980. Analysisof hybridizationbe- corded in 1986 (O'Neil 1986). servedtwo sizablenesting colonies near tweenthe hirundinid generahirundo and petrochelidonin Texas.Auk 97:148-159 Information from breeding bird sur- Falfurrias, the county seat. According , and S. R. MARTIN. 1978. Niche and veys conducted by Richard Albert on to O'Neil the siteshad been utilized only rangeexpansion of the CaveSwallow in the Catarina route in Dimmit County by Barn and Cliff swallowsprior to 1984 Texas. Am. Birds 32:941-946. indicatesthat one siteformerly occupied (O'Neil pers. comm.). Now they are OBERHOLSER, H. C. 1974. The bird hfe by Cliff Swallowshas been completely predominantly,if not exclusively,oc- of Texas. Univ. TexasPress, Austin. taken over by Cave Swallows (Albert cupied by Cave Swallows. RAPPOLE, John H. and Gene W. BLACK- LOCK. 1985. Birds of the Texas coastal While these scattered bits of infor- pers. comm.). bend: abundance and distribution. Texas On June 17, 1986, I accompanied mation are inadequateas a basisfor any A and M Univ. Press,College Station Gene Blacklock, Sharon Bartels (a firm conclusion,they do suggestthat the SELANDER, R. K. and J. K. BAKER. 1957 WelderFoundation volunteer), and Nita Cliff and Barn swallowsare yielding The Cave Swallow in Texas. Condor 59 Hazle (Blacklock'sassistant, a summer nestingniches in the face of the contin- 345-363. intern and Texas A and M University ued aggressiverange expansionby the bxology student), as Blacklock con- Cave Swallow.If such a pattern doesex- ductedan unofficialBreeding Bird Sur- ist, it shouldbe clearlydiscernible from vey alongSH 624 in McMullen County. a more thoroughexamination of recent We examined severalswallow nesting breeding bird surveys throughout the colonies. In each of them Cave Swallows nestingrange of the Cave Swallow. were either in exclusivepossession or It will be interestingto watch what deafly predominant.In culvertscon- happensin the next few yearsat Cliff taming Cliff Swallownests, apparently Swallownesting sites such as the one in from previousseasons, we saw no Cliff Sinton and to note how both Cliff and Swallows. Many of the other nests, Barn swallowpopulations fare at those --Department of History, judging from the amount of plant ma- nestingsites they share with the Cave TexasA & I Universtry, terial used in their construction and Swallow elsewhere. Kingsville,TX 78363

176 AmericanBirds, Summer 1988