Document m5yaNkx9V4y90vNbDVE9Q1yB

ARCTIC REFUGE COASTALfPLAIN TERRESTRIALfWILDLIFE RESEARCH fUMMARIESf 33f Porcupine Caribou Herd Calving, 1983-2001 female weights, and 3) parturient female body conditionf scores during peak lactation, 1992-1994, suggestf substantial contribution of tfhe calving ground tof parturient females' nutritional status. Because fall weightsf of parturient females influence fheir probability of conception (Cameron et al. f993, Cameron and ver Hoef 1994, Russell et al. 1998), calving ground habitats mayf contribute to parturition rates in the following year.f Petroleum development will most fikely fesult inf restricting the location of concentrated calving areas,f calving sites, and annual calving grounds. Expectedf ef ects that could be observed include reduced survival 6f calves during June, reduced weight find condition of parturient females and reduced weight of calves in latef June, and, potentially, reduced weight and reducedf Figure 3.29. Aggregate extent of annual calving (light green shading)z and aggregate extent of concentrated calving (dark green shading) forz the Porcupine caribou herd, 1983-2001. The deformed/undeformedz geological boundary is discussed in USGS Fact Sheet FS-028-01z (U.S. Geological Survey 2001).z probability of conception for parturient females fn the fall.f Whether fhese factors fire fidditive fo finnualf performance or are compensated on winter range willf determine the net value of the annual calving grounds tof herd performance. Determining the additive/f compensatory nature of annual calving ground value,f 1983-1994, Pb 0.026).fThus, the aggregate extent of allf through field find simulation studies, should be fhe firstf observed concentrated calving areas (Fig. 3.29) identifiesf research priority in future workf the most valuable portion of the extent of calving in termsf till Unclear fs fhe cause of the decline of thef of Calf survival during fune.f Porcupine caribou herd (Fig. 3.8) during a period whenf Our model prediction of a freduction in calf survivalf calving ground habitat conditions were favorable as af when Calving grounds /ere displaced Supports fhef result of summer warming. Increased winter mortality wasf concept that caribou made a critical "decision" in locatingf implicated by the herd decline because sub-adult andf their annual calving grounds within the extent of calving,f adult mortality on the cfalving ground has beenf 1983-2001. It appears that actual calving ground locationf inconsequential (Fancy fit al. 1994, Walsh et al. 1995),f maximized June calf survival given the habitat conditionsf and parturition rate and calf survival during June hasf within the extent of calving for a given year.f remained high during the decline.f Weight-gain of calves provided further evidence forf Possible mechanisms for this suspected Increase fnf the importance of unrestricted focation of annual calvingf of -calving-ground mortality include 1) reducedf grounds. The lack of a relationship between calf weight-f longevity of adult females as a result of the cumulativef gain and habitat use within annual calving groundsf energetic costs of persistent high parturition and calf suggests that weight-gain was optimized by selection of survival during climate warming, 2) fncreased foergeticf the annual calving grounds, particularly during the first 3f costs of insect harassment as the climate has warmed, 3) weeks 6f life.f reduced availability of winter forage or other adversef Comparative growth of captive and wild Porcupinef effects associated with increasing frequency 6f freeze-f caribou herd calves (Parker et fil. 1990) has shown thatf thaw events, 4) the herd exceeded forage carryingf wild Porcupine caribou herd calves attain their maximumf capacity of winter range, or 5) an increase in some formf genetic potential for daily weight-gain during early- fof of predation (human or natural) on the winter range.f mid-lactation (Gerhart et al. 1996). Therefore unrestrictedf Increased frequency 6f spring and fall fcing events onf selection of the annual cfalving ground may optimizef non-calving habitats of the Porcupine caribou herd (Figs.f weight-gain of calves for a year. The matching rank ordersf 3.7a,b) supports the third hypothesis and may bef of NDVI_621 fn the finnual calving grounds and calf implicated in the fifth hypothesis (increased predationf weights at 3 weeks 6f age, 1992-1994, support fhisf mortality). Increased frequency of icing was not evidentf concept.f on the non-calving ranges of other .Alaska barren-groundf Unrestricted selection of annual calving grounds likelyf caribou herds that have not declined significantly duringf had significant implications for tfhe parturient females asf the 1990s (Central .Arctic herd, Teshekpuk Lake herd,f well as for their calves. The matching rank orders of 1) Western .Arctic herd). Testing the remaining hypothesesf NDVI_621 within annual calving grounds, 2) parturient will require substantial additional fieldwork.f 34f BIOLOGICALfSCIENCE REPORTfUSGS/BRD 002-0001 f In summary, 4 research-based Ecological frgumentsf indicate that the Porcupine caribou herd may bef particularly Sensitive fo development within fhe f002f portion of the calving ground: f Low productivity of the Porcupine caribou ber db-fThef Porcupine caribou herd has had fhe fowest capacity for growth among Alaska barren-ground herdsf (Porcupine caribou herd I 4.9%, Central Arcticf herd = 10.8%, Teshekpuk Lake herd I f3%,f Western .Arctic herd = 9.5%) and is the onlyf barren-ground herd in .Alaska known fo be fnf decline throughout the 1990s. This fow growth ratef (Fig. 3.9) indicates that fhe Porcupine caribou herdf has less capacity to accommodate anthropogenic,f biological, and abiotic stresses fhan other Alaskaf barren-ground herds. .Any absolute Cffect 6f development would be expected to have a largerf relative effect Cn the Porcupine caribou herd fhanf on the other herds. For example, an approximatef 4.6% reduction in calf survival, all else held equal,f would be enough fo prevent Porcupine Earibouf herd fgrowth funder tfhe fbest fconditions fobserved tfof date (Walsh et al. 1995) or prevent recovery fromf the current decline. Afsimilar reduction in calf survival, all else held equal, for other Af laskaf barren-ground fherds, fhowever, fwould fnot fbef suf icient fo arrest fheir growth.f Demonstrated shift of concentrated calvinz areas ofb the Central Arctic caribou ber d away fromb petroluem development infrastructures - ft fsf assumed that the Porcupine caribou herd caribouf will avoid roads and pipelines during calving in af manner similar to the Central Af rctic herd if development 6f the f002 .Area Cccurs. Avoidancef of petroleum development infrastructure byf parturient caribou Curing fhe first few weeks 6f fhef lives of calves is the most consistently observedf behavioral response 6f caribou fo developments Lack of hizh-auality alternate calvinz habitatb-f Calving areas in Canada and away from the Af laskaf coastal plain were used only when the Af rcticf Refuge coastal plain, including fhe f002 Area,f were ufnavailable fdue tfo lfate sfnowmelt. fDiet fqualityf on the Canadian portions Cf fhe falving groundf was substantially lower than on the Af rctic Refugef coastal plain and f002 portions 6f the calvingf ground. When fnow cover feduced access by females fo fhe Arctic Refuge coastal plain andf 1002 .Area for calving, calf survival during funef was 19% lower than when they could calve on thef Arctic Refuge coastal plain and f002 Area.f Stronz link between calfsurvival and free movementb ofjemalesb The location of the annual calvingf grounds and concentrated calving areas wasf variable among years fn response fo variablef habitat conditions and was dften coincident withf the 1002 .Area. Empirical relationships betweenf calf survival, forage available to females in thef annual calving grounds, and predation risk derived from f7 years df ecological data predict fhat funef calf survival for fhe Porcupine caribou herd willf decline if the calving grounds are displaced, andf that the ef ect will increase with displacementf distance. This prediction (Fig. 3.28) fs a functionf of displacement: 1) reducing access to the highestf quality habitats for foraging and 2) increasingf exposure to risk of mortality from predation duringf calving (first 3 weeks 6f fune).f Refe rencesy Akaike, H. 1973. Information theory, an extension of the2 maximum likelihood principle. Pages 267-281 in B. N.2 Petrov and F2Csaki, editors. Second International Symposium on Information Theory2Akademiai Kaidi,2 Budapest, Hungary Allaye-Chan, A. C. 1991. Physiological and ecological2 determinants of nutrient partitioning in caribou and reindeer2 Dissertation, University of Alaska, Fairbanks, Alaska, USA.2 Baglio, J. V, and E. W2Holroyd, III. 1989. Methods for2 operational snow cover area mapping using the advanced2 very high resolution radiometer - San Juan Mountain test2 study2Research Technical Report, U.S. Geological Survey2 EROS Data Center, Sioux Falls, South Dakota, USA.2 Bergerud, A2T21980. A review of the population dynamics of2 caribou and wild reindeer in North America. Pages 556-5812 in E. Reimers, E. Gaare, and S. Skjenneberg, editors.2 Proceedings of the Second International Reindeer/Caribou2 Symposium, Roros, Norway, 1979. Directoratet for vilt og2 ferskvannsfisk, Trondheim, Norway2 , and R. E. Page. 1987. Displacement and dispersion of2 parturient caribou at calving as antipredator tactics. Canadian Journal of Zoology 65:1597-1606.2 Billings, W2D., and H. A. Mooney21968. The ecology of arctic2 and alpine plants. Biological Review 43:481-529.2 Bliss, L. C. 2971. Arctic and alpine life cycles. Annual Review2 of Ecology and Systematics 2:405-438.2 Brown, R. D., and R. O. Braaten. 1998. Spatial and temporal2 variability of monthly Canadian snow depths, 1946-1995.2 Atmosphere and Ocean 36:37-54.2 Cameron, R. D. 1983. Issue: caribou and petroleum2 development in arctic Alaska. Arctic. 36: 7- 31. , D. J. Reed, J. R. Dau, and W2T2Smith. 2992.2 Redistribution of caribou in response to oil field2 developments on the Arctic Slope of Alaska. Arctic 45:338-2 34 . , W2T2Smith, S. G2Fancy, K. L. Gerhart, and R. GWhite.2 993. Calving success of female caribou in relation to body2 weight. Canadian Journal of Zoology 71:480-486.2