The Hub Conservation Area - Montanans 4 Safe Wildlife Passage

higher quality habitat.Other positive effects of habitat fragmentationinclude changes in predation in which preyspecies are able to disperse before predatorsare able to follow. The fragmented landscapeallows temporary refugia for prey speciesand acts as a temporary barrier to predatorspecies, allowing prey species the opportunityto bolster their population numbers (Fahrig,2003). Other arguments for fragmentationfocus around the consideration that fragmentedpopulations are less likely to be wiped out bya single denominator. For example, a singleconnected population may be eradicated bydisease, whereas, in a fragmented landscapea population in one area may survive while apopulation in another area dies off (Simberloffet al., 1992).Some studies focusing only on habitatfragmentation show potential positive effectson populations, while studies focusing solelyon habitat loss show strong negative effects,leading one to assume that the negative effectsof habitat loss override the positive effectsof fragmentation when the two are studiedtogether. As Fahrig (2003) suggested, it maybe beneficial to define habitat loss and habitatfragmentation as separate phenomena to betterunderstand their impact on wildlife populations.Anthropogenic relationship tofragmentationIn the current socio-political climate, thereare questions about whether anthropogenicchanges to the environment are responsiblefor habitat loss and fragmentation and thusthe cause of the resulting negative effectsupon populations, or merely a reflection ofnaturally occurring processes. The literaturewe reviewed shows that although the cause ofhabitat fragmentation and habitat loss is dueto a combination of human and natural factors(Apps and McLellan, 2006), human disturbanceappears to be the dominating factor. Laliberteand Ripple (2004) mapped habitat rangecontraction for 43 species across North America.They then compared this map with a map ofthe “human footprint” created by Sanderson etal. (2002). They found that range contractionsin North American species closely coincide withhuman disturbance of the land, suggesting thatthe negative effects of habitat loss and habitatfragmentation on wildlife populations are largelydue to human land use.As habitat fragmentation continues tocreate barriers to animal movement, habitatconnectivity grows increasingly vital inpromoting the long-term survival of species.Maintaining connectivity where it still existsand creating connectivity where it has been lostis of critical importance in land managementplans directed at counteracting the effects offragmentation on wildlife populations.HABITAT CONNECTIVITYDefining connectivityConnectivity is defined as the degree to whichthe landscape facilitates or impedes movementamong resource patches (Taylor et al., 1993).For land management purposes it is important toemphasize the distinction between structural andfunctional connectivity. Structural connectivity isa spatial connection of the landscape. Functionalconnectivity provides a conduit for animaldispersal. Functional connectivity implies animalmovement, whereas structural connectivity isstrictly spatial (Tischendorf and Fahrig, 2000).For example, if two habitat patches containingseparate black bear subpopulations are connectedby habitat that is incompatible with black bearneeds, the landscape would be consideredstructurally connected, but not functionallyconnected. It would only be functional if theblack bears were able to use the connectinglandscape. Therefore, when planning landscapeconnectivity, functional connectivity is thedesired outcome, and the ability of the species ofinterest to utilize the connected landscape mustbe taken into consideration. It is also importantto note that the same landscape may potentiallyprovide varying amounts of connectivity fordifferent species (Tischendorf and Fahrig, 2000;With and Crist, 1995). For example, a landscapeproviding functional connectivity for a bobcat36