THE EFFECT of MINING and BLASTING on BREEDING PRAIRIE FALCON (Falcomexicanus) OCCUPANCY in the CABALLO MOUNTAINS, NEW MEXICO

Home , Caballo Mountains

THE EFFECT OF MINING AND BLASTING ON BREEDING PRAIRIE FALCON (Falcomexicanus) OCCUPANCY IN THE CABALLO MOUNTAINS, NEW MEXICO

JAMESC. BEDNARZ

ABSTRACT- I surveyed3 smallisolated mountain ranges in southcentralNew Mexicofor the presenceof breeding Prairie Falcons(Falco mexicanus). Of these,the CaballoMountains were intensivelyimpacted by mining and blasting activity,while the other 2 wereessentially undisturbed. No falconswere found in the disturbedmountain range, but a totalof 8 nestswere documented in the 2 controlranges. The 3 areaswere extremely similar in all respectsexcept for the number of mining claims.

Almost no published information is available includesonly that contiguousmountain habitat that containscliffs concerning the impactsof mining and blasting on potentiallyusable as nestsites. Foothill habitatswithout cliffs sur- rounding mountain rangeswere not included in this area mea- birds of prey. The limited data available are re- surement. stricted to observationof short-term impacts on Geologically,the Fra Cristobaland the Caballomountains are activelynesting raptors (Stahlecker and Alldredge nearlyidentical, consisting primarily of marinesedimentary rock 1976). Severalworks (Allen 1979, Call 1979, Becker resultingfrom an uplift along the Rio Grande Rift (Kelly and Silver 1952).The Florida Mountainsdiffer in this respectas they and Ball 1981) contain speculationabout the im- are of a rhyoliticformation. pending impactsof mining operationson raptors Field surveysin all 3 areas emphasizedthe most prominent and offer suggestionsto minimize potentially ad- cliffs,which in my experienceare preferred by PrairieFalcons for verseeffects. Follow-up or controlled experimental nestsites. I have found that cliffs < 50 m in heightare generally studiesof suchimpacts are virtually nonexistent. used only in New Mexico when larger cliffs are not available. During this studyI examinednumerous smaller cliffs (< 50 m in Herein I report the numbersof breeding Prairie height)but none containedactive Prairie Falconnests. Surveys Falconsobserved during a surveyof 3 small and were accomplishedby climbingto an observationpoint that al- very similar mountain rangesin southcentralNew lowed observationof 1 or more large cliffs ( > 50 m of vertical or Mexico. One of these ranges, the Caballo Moun- near vertical rock). I studied cliffs for falcon-like excrement ("whitewash")with binocularsand spottingscope and watchedfor tains, hasbeen intensivelyimpacted by mining op- falconactivity for periodsof severalhours as outlined by Bondet erations and associated human intrusions for sev- al. (1977) and Call (1978). Cliff observationswere made in the eral years. The other 2, the Fra Cristobal and early morning or late afternoon.After cliffs were watchedfor at Florida mountains, have minimal or no disturbance least2 h withoutsuccess, I approached from belowand attempted from mining. If mining and the associatedblasting to disturb(by shoutingand clappinghands) any previouslyunob- servedraptor. Observationswere discontinuedat cliff siteswhen hasno influenceon PrairieFalcon nest occupancy, I nestsof the Golden Eagle(Aquila chrysaetos) or Prairie Falconwere would expectthe numbersof breedingfalcons at all located. Field examinations in all areas were conducted when 3 studyareas to be similar.The habitatand number falconswere expectedto be incubatingor possiblytending small of cliffs at all 3 mountain rangesseems comparable. young. Accessibilityof mountain rangesdiffered considerably.The STUDY AREAS AND METHODS Caballorange had numerousroads on talusslopes providing easy accessto excellentobservation perches close to prominentcliffs. I surveyedthe Fra CristobalMountains on 15-18 April and On the other hand, the Fra Cristobalrange was extremely remote 19-23 May 1980,the FloridaMountains on 21-25 April 1980,and and almost no roads approachthe foothills. Although I spent the Caballo Mountains on 5-9 May 1980. These ranges were nearlytwice as many field daysin thisarea, most of the additional searchedfor raptors as part of a larger statewidesurvey with time was used in travel. Access roads circled around the Florida emphasison endangeredraptors on landsadministered by the Mountains,but generallystopped at the baseof the talus.Search Bureauof Land Management(BLM). These3 rangesare isolated, and observationeffort at all 3 rangeswas comparable (Table 2). but locatedin relativelyclose proximity (Fig. 1). The climateof all 3 ranges is similar; all are extremely dry with summer daytime tempoften exceeding 38 ø C and wintertemp commonly dropping RESULTS AND DISCUSSION below 0ø C at night. The vegetationin all 3 study areascan be I located 5 active Prairie Falcon nests in the characterized as creosote bush (Larrea tridentata) dominated shrublandon the lower slopesgrading into a sparsejuniper-oak Florida range and 3 activesites in the Fra Cristobal (Juniperusspp.; Quercusspp.) woodland on the summitsand range (Table 2). No nestsor large falconswere upper, north-facingslopes (Table 1). Elementsof Chihuahuan observed in the Caballo Mountains. I also found 2 desertvegetation (e.g. Prosopis glandulosa, Yucca spp., Opuntia spp.) are •nore common in the Florida Mountains. Suitable cliff habitat, Golden Eaglenests in the Fra Cristobalrange. In all elevationand topographicrelief abovebasins are comparablefor observablephysical and ecologicalcharacteristics, all 3 studyareas (Table 1). Area of suitablecliff habitat (Table 1) exceptfor the intensityof mining, the 3 mountain

16 RAPTORRESEARCH 18(1): 16-19 SPRING1984 J^MESC. BEI)S^RZ 17

Table 1. Characteristicsof 3 mountain study areas in southcentralNew Mexico.

Fra Cristobal Caballo Florida Mountains Mountains Mountains

Approx. area of suitable cliff habitat (km") 36 26 34

Maximum elevation (m) 2083 2301 2270

Elevation relief above basin (m) 730 1000 915

Primary rock type marine marine rhyolite sedimentary sedimentary

Dominant vegetation creosote creosote creosote-mesquite community on slopes shrubland shrubland shrubland Dominant vegetation juniper-oak juniper-oak juniper-oak community at summit woodland woodland woodland

rangesappeared to be extremelysimilar (Tables 1 during 1 of my 5 field surveydays in this area. and 2). Numerous shallow shafts were blasted into rock The area I surveyed(26 km2) in the Caballo wallsand talus slopes throughout the range.These Mountains contained 125 active mining claims blast shaftswere concentratedat or just abovethe (miningclaim records dt 21 June 1980,BLM State baseof both large and smallcliffs examined.In Office, SantaFe, New Mexico). I witnessedblasting addition, severalladders were bolted to the vertical

Table 2. Resultsof field surveyfor Prairie Falconnests and activemining claimsin 3 mountainstudy areas in southcentral New Mexico.

Fra Cristobal Caballo Florida Mountains Mountains Mountains

Fielddays 9 5 5 Cliff observation (time h) 25.9 25.0 25.0

# of major cliffs examined( > 50 m in height) 10 8 9 # of major cliffs not examined( > 50 m in height) 3 3 4 # nests located 3 0 5 Miningclaims recorded at BLMoffice 0 125 29 Miningactivity observed none intense none 18 PRAIRIE FALCONIN NEW MEXICO VOL. 18, NO. 1

however,this is unlikely becausethe Fra Cristobal Range30 km to the north and the Floridarange 90 NEWMEXI Nl km to the southprovided enough prey to supportat least8 pairs.The vegetativecover in the vicinityof all rangeswas extremely similar in all appearances. An absence of Prairie Falcons from the Caballo Mountains could only be caused by an extreme depressionin prey populationsin a very localized I ALBUQUERQUEarea around thesemountains, which seemshighly RIO GRANDE/RIVER improbable. The Florida Mountainswere usedby almosttwice as many falcon pairs (5 vs 3) as the Fra Cristobal Mountains.This difference may be due to the dis- FRACRISTOBALMOUNTAINS persionof cliffsin the respectiveranges. Prominent cliffs in the Florida range were uniformly distri- buted alongthe westface, whereas in the Fra Cris- ,ABALLOMOUNTAINS tobal range, cliffs were aggregatedin 2 relatively FLORIDA MOUNTAINS smallparts of the range(1 aggregationin the north

, portionand the other in the south).The uniform ._• 0I 100I cliff dispersionprobably enables more falconsto km use a small mountain range without intruding into defended areas around neighboring eyries. The cliffsin the Caballorange are distributedin a man- Fig. 1. Locationof 3 mountaintudy areasin southcentral ner similar to that found in the Florida Mountains. New Mexico. Therefore, I would expect to find between 3-5 Prairie Falcon nests if the Caballo Mountains were rock wallsand 2 compressorswere parked high on undisturbed. the talus slopesadjacent to cliffs. All raptors have individual differencesin the In the Florida Mountains,with 29 mining claims amount of disturbance that will be endured. I am in the area surveyed(34 km2), I observedno evi- awareof 1 casein Wyomingwhere a pair of Prairie denceof activemining. I did note 1 probablemin- Falconstolerated intensivecoal mining activityin- ing road leadingup the talusslope on the north side cludingblasting, heavy equipment operation, and of the mountain range. No evidenceof mining ac- settlingpond construction within 75 m of the nest tivity wasobserved in the Fra Gristobalrange. (S. Platt, pets. comm.). Falconsreturned to the The absenceof nestingPrairie Falconsfrom the samegeneral area for 3 consecutiveyears (1981- Caballo range was an unexpectedfinding. Promi- 1983) followingthe disturbance.These birds were nent cliffs in the 2 control study areas provided not successfulin producing young in any of the habitat for 8 pairs of breeding falcons.Evidence of yearsmonitored, but adverseweather conditions mining activityand related human disturbancewas may have been a factor (S. Platt, pets. comm.).In obvious in the Gaballo Mountains, but minimal in this casethe primary disturbancewas limited to 1 the 2 control ranges. breedingseason and wasapparently of similarin- Breeding falcons may have occurred in the tensitythroughout the disturbanceperiod. Toler- Gaballo Mountains in 1980, but if so, they must ant falconsmay more readilyhabituate to a steady, have occupiedthe smaller, less preferred cliffs. predictableintensity of disturbance.In contrast, Given that I did not observeany Prairie Falcons, miningand blastingactivity in the impactedrange during the field survey,I suspectthat few, if any, surveyedduring this study was probably of a highly breeding falconswere present. No historicaldata variable and unpredictable nature. on raptor breeding populationsare availablefor Blastingand mining operationsin the Caballo any of the 3 rangessurveyed. Mountains are primarily the endeavaorsof indi- A possiblealternative explanation is that low vidual prospectorsor small part-time mining numbers of availableprey made the Caballo range partnerships.One larger corporationwas mining unsuitableas falcon breeding habitat in 1980. I feel, barite at the time of my survey,but this miningwas SPRING1984 JAMESC. BEDNARZ 19 in the foothills >3 km from the area of suitable BE½•:ER,D. M., ANDI. J. B^I•I•. 1981. Impactsof surface nestingcliffs. Sincethe climate in this area is rela- mining on Prairie Falcons: recommendations tbr tively mild and there are no restrictonson blasting, monitoring and mitigation. Unpubl. m.s., Montana I assumethat all active claimsare worked periodi- CooperativeWildlife ResearchUnit, Montana State callythroughout the year. All mining in the survey University,Missoula. 38 pp. area seemedto be on a part-time basis.Placer gold BOND,F. M., C. R. CRAIG,J.H. ENDERSON,A. W. HEGGEN, C. E. KNODER,J. V. KUSSM^N,M. W. NELSON,R. D. was probablythe principle mineral that was being PORTER,D. L. WILLS. 1977. American PeregrineFal- extracted.Also, much of the mining activityis sus- con recovery plan (Rocky Mountain and Southwest pected to be treasure hunting in searchof legen- populations).U.S. Fishand Wildl. Serv. 183 pp. dary "Spanishgold" thought to be hidden in the C^LI, M. W. 1978. Nesting habitats and surveying Caballo Mountains (T. Custer, BLM Geologist, techniquesfor common western raptors. U.S.D.I., White SandsResource Area; pers. comm.). Trea- Bureau of Land ManagementTechnical Note TN- sure hunters may pursue their hobby under the 316. 115 pp. facadeof a mining claim which allowsthem to leg- CAI.L, M. W. 1979. Habitat managementguidelines for ally blast natural cliff faces. The combination of birds of prey. U.S.D.I., Bureau of Land Management mining and treasure hunting has resulted in an TechnicalNote TN-338.67 pp. ELLis, D. H. 1981. Responsesof raptorial birds to low extremely high intensityof blastingin the Caballo level militaryjets and sonicbooms. Unpubl. m.s., In- Mountains. stitutefor Raptor Studies,Oracle, Arizona. 59 pp. In conclusion,I believethe data presentedhere KELLY,V. C., ^ND C. Sn.VER.1952. The geologyof the suggestthat there is a differencein Prairie Falcon CaballoMountains: with specialreference to regional nestoccupancy between the CaballoMountains and stratigraphyand structure and to mineral resources, the 2 control rangesmost likely due to blastingand includingoil and gas.University of New MexicoPubl. mining or associatedhuman activities. To my in GeologyNo. 4. 286 pp. knowledge,no study has examined the long-term STAH[ECKER, D. W., AND A. W. AI•LDREDGE. 1976. The effectsof miningor blastingon occupancyof raptor impactof an underground nuclearfracturing experi- ment on cliff-nestingraptors. Wilson Bull. 88:151- nest sites, but short-term impacts have been 154. documented(Stahlecker and Alldredge 1976). Ellis ( 1981), basedon a 2 y studyof simulatedsonic boom Department of Biology, University of New Mexico, Albuquer- noise, implied that both adverse short-term and que, NM 87131. long-term impactsof suchactivities were probably negligible on nesting raptors. My results indicate Received17 December1983; Accepted27 April 1984 that this conclusion cannot be extended to more intensiveblasting and mining activities,and I urge further observation,and particularly, controlled experimental studiesto addressthe long-term impactsof suchdisturbances on breeding raptors.

ACKNOWLEDGEMENTS I thank Gregory Schmitt, Marshall C. Conway, and John P. Hubbard for providingencouragement during the courseof field surveys.Pat L. Kennedy, George Anne Thibodeau, Buck Cu!!y, Dale W. Stahlecker,and John P. Hubbard thoroughlyreviewed earlier drafts. Steve Platt shared with me some of his data and thoughtson the impactsof miningon raptors.Mr. Joe Williams, Mr. Crawford,and other ranchersgave me permissionto enter and campon their !and.This workwas supported by the Bureau of Land Managementand the New MexicoDepartment of Game and Fish,Endangered Species Program.

LITERATURE CITED AI•I•EN,G. T. 1979. Assessmentof potential conflicts betweennesting raptors and human activitiesin the LongPines area of southeasternMontana -- with spe- cialemphasis on uraniumdevelopment. M.S. Thesis, WashingtonState University, Pullman. 109 pp.