Bat Use of Remnant Old-Growth Redwood Stands
Total Page:16
File Type:pdf, Size:1020Kb
Bat Use of Remnant Old-Growth Redwood Stands WLLLARi1 j. ZIELINSa* AND STIE\;EN T. GELL U.S. Forest Service, Pacific Southwest Research Station, Redwood science;, hrcata, CA 95521, U.S.A. Abstract: ~Ziostof the old-growth redzuood (Sequoia sempen~irens)in Cal@t*tzia has been cut; reg-enerati~zg forests willpt-obably never resemble those that were haniested, and what old growth remains on priuate land occurs in small, isolated remnant patches. The landscapes in which these stands occur dzyfer so markedly from their original condition that their value as habitat to mauy species of wildlzye, iincluding bats, is un- knoufn.Previozks research in zmnfragmented redwoodforests demonstrated that bats use basal hollows itz old- growth redufoodsas roosts. We sought to determine whether bats use similar old-growth trees as roosts when they occur in small, remnant patches of isolated old growth on commercial forest land. We compared bat oc- currence in remnant and contiguoz~sstands by collecting guano in traps suspended in hollows and by moni- toring flight activity with ultrasonic bat detectors. Hollouls in trees zuithin the remnant stands had signzyi- cantly more guano deposited per tree than the trees within the contiguous forest. me mean rzumbers of bat passesper night were statistically indisti~zguishablebetween the two treatments, aldhozk@ mean Fight uctivity in the remnant stands was greater than in the contiguous forest. Bats frequently used basal hollou~sin small ((5 ha) stands of remnant old growth, u~hichmay be due to the closer proximity of remnants to stream courses, to their greater interface with edge where foraging success may be greater, or to the fact that the lower density of hollow-bearirzg trees in remnants than in contiguous forest favored greater use per tree. Sig- nzyicant use of small, residual old-growth redwood provides reason to maintain these remnants in managed landscapes as potentially important habitat for forest bats. Uso de Reinanentes de Bosques Maduros de Secoyas por Murcielagos Resurnen: La mayorfa de 10s bosques maduros de secoyas (Sequoia sempervirens) de Calzyornia ban sido tal- ados, 10s bosques en regeneration quiza rzunca sean lo gue alguna vez fueron 10s bosques talados y lo gue gueda de bosgue maduro en propiedudes privadas ocurre en parches renzanentes pequefios y aislados. Los paisajes en los cuales estos remanentes ocurren difieren tan marcadamente de las cotzdiciorzes originales que su valor como hdbitat para muchas especies de uida siluestre, incluyendo a los nzurci6lagos es desconocido. Inuestigaciones preuias en bosques no fragmentados de secoyns demostrnron que 10s murcie'lagos utilizan huecos en 10s &boles como perchas. Intentamos determinar si 10s murci6lagos usan drboles similat-es a 10s utilizados en bosques maduros cuando estos ocurren en parches de bosque maduro pequeGos y aislados etz tiemsforestales comerciales. Comparatmos la presencia de mut-cie'lagos en sitios renzanentes y etz sitios con- tiguos mediante la coleccion de guano en tmtnpas suspendidas en agujeros y por motzitoreo de la nctividad de vuelo ~nediantedetectores ultmscjnicos de mu~"ci6lagos.Los agujeros en 10s urboles dentro 6le 10s sitios re- tnanetztes tuuieron significatiuamerzte mas guano depositado por arb01 yue los drboles dentro de bosgues contiguos. El nzimero promedio de murci6lngos que pasaron por rzoche fzce estadisticamente irzdistizzguible entre los dos tratamientos, aungue la actiuidadpromedib de vuelo en 10s bosgues remanentesfae nzayor yue en 10s bosques copztigzcos. Los murcie'lagosfrecue~ztefnenteutilizan agujeros busales epz porciofzes remanentes peqzceAas de bosque madzaro (<5 ha), lo czcalpuede deherse a fa cerctzna proximidad de los I-emanentesn los cauces de an-oyos, su gt-an interface con el borde donde el e'xito deforrajeo &he ser mayor, o a1 hecho de yzme la densidad baja de drboles con agzajeros en las bosques remanetztesfacorece un mqyor uso por drbol. El uso signzyicatiuo de pequeAos bosques residuales maduros de secoyas provee una razon para manterzer estos re- matzentes en paisajes manejados como un hdbitat potencia1 para murcielagos de bosque. * email u?zieZinski/[email protected]. us. Paper submitted October 17, 1997; revised manz~scriptaccepted Ma!y 20, 1998. Conservation Biology, Pages 160- 167 Volume 13, No. 1. February 1999 Corsi et nl editors. Large-scale ecology and conservation biology. Blackwell 210 in D. R. McCullough, editor. Metapopulations and wildlife con- Scientific Prtblications, Oxford, Iinited Kingdom. sesvation. Island Press, Washington. D.G. McKelvey, K., B. R. Noon, and R. H. Larnberson. 1992. Consenration Promberger, C., and W. Schroder, editors. 1993. Wolves in Europe: sta- planning for species occupying fragmented landscapes: the case of tus and perspectives. Munich Wildlife Sociery, Ettal, Gemany. the Northern Spotted Owl. Pages 424-450 in P. &I. Kareiva. J. G. SAS Institute, Inc. 1985. SAS user's guide: statistics. Version 6.04. Gary. Kingsolver, and R. B. Huey, editors. Biotic interactions and global North Carolina. change. Sinauer Associates, Sunderland. Massachusetts. Saunders. D. A., R. J. I-lobbs, and C. Margules. 1991. Biological conse- Xech, L. D. 19'0. The wolf: the ecology and behavior of an endan- quences of ecosystem fragmentation: a review. Consemation Biol- gered species. Natural Histoll; Press. Doubleday, New York. om 518-32. Mech. L, D. 1995. The challenge and opportunirj, of recovering =oLf Sokal. R. R.. and F. J. Rohlf. 1995, Biometq-. W. 11. Freem, New York. populations. Consen~ationBiolog) 9:270-278. Stoms. D. Sf.. F. W. Davis, and C. B. Cogan. 1992. Sensitivity of wildlife habitat mocfels to uncertainties in GIs data. Photogrammetric Engi- Mech, L. D , S. H. Fsitts, G. L. Radde, and W. J. Pad. 1988. Wolf distri- bution and road density in S4innesota. Wildlife Society Bulletin 16: neering & Remote Sensing 58:843-850. 85-87. Stornler, F. A.. and D. H. Johnson. 1986. Introciuction: biornetric ap- proaches to modeling. Pages 159-160 in J, Verner, M. L. Morrison, Meriggi, A., and S. Lovari. 1996. A review of wolf predation in south- and C.J. Ralph, editors. Wildlife 2000: modeling babitat relationships ern Europe: does the wolf prefer wild prey to livestock?Journal of of terrestrial vertebrates. University of Wisconsin Press, Madison, Applied Ecology 33: 1561- 1571. Thiel, R. P. 1985. The relationship between road densities and wolf Mladenoff, D. J., and T. A. Sickely. 1998. Assessing potential gray wolf habitat suitability in Wisconsin. American Midland Naturalist 113: restoration in the northeastern United States: a spatial prediction of 404-107. favorable habitat and potential population levels. Journal of Wild- Tomlin, C. D. 1990. Geographic information systems and cartographic life Management 62:1 - 10. modelling. Prentice-Hall, London. Mladenoff, D. J., T. A. Sickle)?,R. G. Haight, and A. P. Wydeven. 1995. Turner, M. G., G. J. Arthaud, R. T. Engstrom, S. J. Hejl. J. Liu, S. Loeb, A regional landscape analysis and prediction of favorable gray wolf and K. McKelvey. 1995. Usefulness of spatially explicit population habitat in the northern Great Lakes region. Conservation Biology 9: models in land management. Ecological Applications 5: 12- 16. 279-294. Verbyla D. L., and J. A. Litvaitis. 1989. Resampling methods for evaluat- Noss, R. S. 1992. Issues of scale in conservation biology. Pages 240- ing classification accuracy of wildlife habitat models. Environmen- 250 in P. I,. Fiedler and S. K. Jain, editors. Conservation biology the tal Managenlent 13:783-787. theosy and practice of nature conservation, preservation and man- Weaver, J. L., P. C. Paquet, and L. F. Ruggiero. 1996. Resilience and agemmt. Chapman and Hall, New York. conservation of large carnivores in the Rocky Mountains. Conser- Noss, R. F., H. B. Quigley, M. G. Hornocker, T. Mesril, and P. C. Paquet. vation Biology 10:964-976. 1996. Conservation biology and carnivore conservation in the Wiens, J. A. 1996. Wildlife in patchy environments: metapopulations, Rocky Mountains. Conservation Biology 10:949-963. mosaics and management. Pages 53-84 in D. R. McCullough, edi- Pinchera F., L. Boitani, and I;. Corsi. 1997. Application to terrestrial tor. Metapopulations and wildlife conservation. Island Press, Wash- vertebrates of Italy of a system proposed by IUCN for a new classi- ington, D.C. fication of national Red List categories. Biodiversity and Consesva- Zimen, E. 1978. Der Wolf, Mythos und Verhalten. Meyster Verlag, Wien, tion 6:959-978. Austria. Price, M. V , and M. Gilpin. 1996. Modelers, mammologists. and meta- Zimen, E.. and L. Boitani. 1975. Number and distribution of wolves in populations: designing Stephens' kangaroo rat reserves. Pages 217- Italy. Zeitschsift fiir Saugetierkunde 40:102- 112. Conservation Biology Volume 13, No. 1, Febn~ary1999 Introduction and exists as young, second- or tbird-growth forest. Old- growth forest that occurs outside the bomdaries of fed- With the exception of extensive stands that may occur in eral and state parks does so in the form of small, remnant reserves such as national parks, remnant patches are stands that punctuate the landscape of young forest. about aU that remain of the original forest cover that pre- These small stands are increasingy valued by ddlife ceded European settlement in the United States. Approxi- managers for the unique and rare elements they pro- mately 85%of the primary forests in the United States and vide-large and sometwes hollow live trees, large snags, 95-9896 of those in the conteminous 48 states have been large logs-and by environmentalists who wish to protect harvested (Postel & Ryan 199I). The result has been an in- original forests that are not cunently in reserves. crease in the number of forest fragments, amount of edge, With the knowledge that bats use hollows in old- and isolation of remnant forest patches (Groom Sr Schu- growth redwood forests, we became interested in deter- nlaker 1993). In many cases, small patches of original for- mining whether this use was iduenced by the type of est are all that remain as examples of particular vegetation stand in which the hollow-bearing tree occurred.