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Microhabitat Factors Influencing Predation and Success of Suburban Blue Jay Cyanocitta Cristata Nests Author(S): Keith A

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Microhabitat Factors Influencing Predation and Success of Suburban Blue Jay Cyanocitta Cristata Nests Author(S): Keith A Nordic Society Oikos Microhabitat Factors Influencing Predation and Success of Suburban Blue Jay Cyanocitta cristata Nests Author(s): Keith A. Tarvin and Kimberly G. Smith Source: Journal of Avian Biology, Vol. 26, No. 4 (Dec., 1995), pp. 296-304 Published by: Wiley on behalf of Nordic Society Oikos Stable URL: http://www.jstor.org/stable/3677044 . Accessed: 04/08/2014 16:20 Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at . http://www.jstor.org/page/info/about/policies/terms.jsp . JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. Wiley and Nordic Society Oikos are collaborating with JSTOR to digitize, preserve and extend access to Journal of Avian Biology. http://www.jstor.org This content downloaded from 132.162.168.180 on Mon, 4 Aug 2014 16:20:56 PM All use subject to JSTOR Terms and Conditions JOURNAL OF AVIANBIOLOGY 26: 296-304. Copenhagen1995 Microhabitat factors influencing predation and success of suburban Blue Jay Cyanocittacristata nests Keith A. Tarvin and Kimberly G. Smith Tarvin,K. A. and Smith,K. G. 1995. Microhabitatfactors influencing predation and success of suburbanBlue JayCyanocitta cristata nests. - J. AvianBiol. 26: 296-304. We examinedhow microhabitatfeatures surrounding nest-sites influence probability of nest predationby testingunique predictions generated from the "distanceto human activity,"the "habitatcomplexity," and the "multiplenest-site" hypotheses. During springand summer1990, we quantifiednine featuresof nest-sitesand 11 featuresof 0.1 ha nest-patchessurrounding 42 nests of suburbanBlue JaysCyanocitta cristata in Fayetteville,Arkansas, to determinedifferences associated with depredatedand suc- cessful nests. Overallnesting success was 52% and meandaily survivalrate of nests was 0.983 (? 0.004 SE). Twenty-fournests fledged at least one young, and 18 failed as a resultof nest predation.Features of thenest-site, including nest height,size of the nest tree, andnest concealment,were not relatedto nest predation,although distance from a nest to the nearestbuilding was inverselyrelated to durationof nest survival. The latterrelationship suggests human activity may decreasenest predationin subur- ban areas.Density of vegetationsurrounding nests did not influencenest fate, thus providingno supportfor the habitatcomplexity hypothesis. Instead, failed nests oc- curredin patchescontaining fewer trees of the samespecies, size class andvine cover as the nest tree. Becausethis patternwas not an effect of size or species of eitherthe nest tree or neighboringtrees, nor an effect of vines in the nest tree or neighboring trees, it providessupport for the multiplenest-site hypothesis. K. A. Tarvinand K. G. Smith,Department ofBiological Sciences, University of Arkan- sas, Fayetteville,AR 72701, USA.Present address of K. A. Tarvin:Department of Biology,University of SouthFlorida, Tampa, FL 33620, USA. Because nest predationis a majorfactor limiting breed- ris 1980) suggests increasingspatial habitat complexity ing success in open nesting passerinebirds (e.g., Rick- reducespredator search efficiency by impedingtravel or lefs 1969, Martin1988, 1992), naturalselection should by inhibitingtransmission of visual, auditory,or chemi- favorbirds that behave in ways thatreduce the probabil- cal cues that predatorsuse to find nests. The "multiple ity of nest predation.If qualityof nesting microhabitats nest-site"hypothesis (Martin and Roper 1988) suggests differs amongpotential nest-sites, such that nests differ thatincreasing numbers of potentialnest-sites surround- in the likelihood of being found by a predator,and if ing an actual nest may reduce predatorefficiency be- such differencesare identifiable,selection should favor cause predatorsare more likely to encounterempty nest- birdsthat choose nestingmicrohabitats associated with a sites, and, being rewardedless frequently,are more low probabilityof nest predation(Martin 1992). likely to move to a differentarea. The "distanceto hu- A numberof hypotheseshave been proposedto ex- man activity" hypothesis (Collias and Collias 1984) plain how nesting microhabitatmay influencenest pre- states that nests closer to human activity suffer lower dation (Filliateret al. 1994). Here we examinetwo hy- predationrates because humanactivity deterspredators potheses that addressthe mannerin which structureof fromusing such areas. the habitatsurrounding nests may affect predatorsearch In this study we quantifiedmicrohabitat features sur- efficiency, and a thirdthat addressesthe way in which roundingnests of suburbanBlue Jays Cyanocittacris- the suburbanlandscape may influence nest predation. tata to determinedifferences associated with failed and The "habitatcomplexity" hypothesis (Bowman and Har- successfulnests. We also tested uniquepredictions gen- ? JOURNALOF AVIANBIOLOGY 296 JOURNALOF AVIANBIOLOGY 26:4 (1995) This content downloaded from 132.162.168.180 on Mon, 4 Aug 2014 16:20:56 PM All use subject to JSTOR Terms and Conditions erated from the habitat complexity,multiple nest-site, summer, 1990, in neighborhoodscontaining park-like and distance to human activity hypotheses to examine standsof oaks Quercusspp., elms Ulmusspp., and sugar how microhabitatfeatures may influencethe probability maples Acer saccharum that formed patchy canopies of nest predation.A unique predictionof the habitat over lawns, scatteredshrubs, and copses. Lawns often complexityhypothesis is thatthe probabilityof nest pre- were borderedby overgrownbrush along propertylines, dation should decrease as vegetationdensity increases. small streams,or vacant lots. Several dense woodlots, The multiplenest-site hypothesisuniquely predicts that rangingin areafrom a few to tens of hectares,were in- the probabilityof nest predationshould decreaseas the terspersedthroughout the city. numberof potential,but unoccupied,nest-sites within an Commonpotential nest predatorson our studysite in- area increases.Because potentialnest-sites are difficult cluded gray squirrelsSciurus carolinensis, house cats to identifyfor species that nest in a varietyof nest sub- Felis domesticus,American Crows Corvusbrachyrhyn- strates,we tested the corollaryprediction that variables cos, and other Blue Jays. Less common predatorsin- thatreflect similaritiesbetween the actualnest-sites and cluded black rat snakes Elaphe obsoleta, House Wrens the surroundingvegetation are good predictorsof nest Troglodytesaedon, raccoonsProcyon lotor, and Virginia fate. Finally, we tested a predictiongenerated from the opossums Didelphis virginiana.We did not attemptto distanceto humanactivity hypothesis, that probability of assess relative impact of each predatorspecies on our nest predationincreases with distancefrom nest to near- study site; however,Blue Jays usuallyresponded vigor- est building. ously to the presenceof AmericanCrows and gray squir- rels nearnest-sites, indicating jays view those species as threatening.We observedAmerican Crows taking eggs from one jay nest, and an unmarkedBlue Jay flying Methods fromanother nest with an egg in its beak.Eggs of a third jay nest containedpuncture holes characteristicof egg Study species destructionby House Wrens (Belles-Isles and Picman Blue Jays nest in deciduousand mixed coniferous/decid- 1986). We observedno otherpredation events. uous forest habitatsacross the easternUnited States and southernCanada. In moderntimes, Blue Jays have be- come numerousin suburbanhabitats, where build they success nests in a wide arrayof tree species.Nests may be as low Nesting as 1 m above the groundor near the top of the nest tree, Upon discovery,nests were checkedfor activityevery 1 althoughtypical nest height is between 3 and 8 m (Tay- to 6 days; usually every 2-3 days dependingon number lor 1965, Woolfendenand Rohwer 1968). Nests consist of activenests on any given day.We used Student'st test of a ratherbulky outershell made of sticks surrounding to determinewhether frequency of nest checks influ- a compactcup. They may be placed near the end or at enced probabilityof nest predationby comparingthe ra- the base of a branch,directly on a largehorizontal limb, tio of numberof nest checks per nest observationperiod or in a fork in the trunkof the nest tree. Nests may or (in days) betweensuccessful and depredatednests for all may not be concealedby vegetation,and adultsusually nests that were checked more than once. If a nest ap- vigorouslydefend their nests from potentialnest preda- peared inactive during a nest check, contents were tors. Females incubate eggs and brood nestlings, and checked with a mirrormounted on a pole. Nests were food for incubatingfemales and young nestlingsis pro- consideredactive if at least one egg or nestlingwas seen vided by males. Regardlessof whethernests are well in a nest, or if an adult was observedbrooding on the concealed by vegetation,provisioning males approach nest over a spanof at least threedays. the nest indirectly,usually moving to severalperches in Nests were consideredsuccessful if they survivedat the vicinity of the nest before deliveringfood to the sit- least 34 days beyond the laying of the penultimateegg. ting female or nestlings. Hardy (1961) concludedthat Throughoutthe geographicrange of the Blue Jay, the Blue Jays build "false"nests, small
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