Impacts of a Highway Expansion Project on Wolves in Northwestern Wisconsin
1999
Research was conducted to evaluate the impacts of upgrading 71 km of US Highway 53 (US 53) from 2-lanes into 4-lanes on wolves ( Canis lupus ) in northwestern Wisconsin. The authors main objectives were to assess the impacts of the highway project on resident and dispersing timber wolves, and to identify critical habitats and travel corridors for wolves. FiftyBnine timber wolves (33 males ; 26 females) were radio-collared and monitored. Howling surveys were conducted during July- September to determine numbers of pups produced in each known pack. Winter track searches and aerial observations were used to determine the number of wolves in each pack and to detect the presence of newly-established packs. All known wolf mortalities were investigated and recorded. To date it does not appear that the US 53 highway project negatively impacted resident or dispersing wolves. The resident wolf population within the 7,000 km 2 study area increased from 18 animals in 1994 to 61 wolves in 1999. More than 1/3 of the wolf pack territories in the study area in 1999 were adjacent to the highway construction project. Thirteen of 20 radio-collared dispersing wolves encountered US 53 in their travels and all but one of them crossed it, some several times. Although 10 wolves were killed by vehicles in this study, only 3 of those accidents occurred along US 53. It appeared that dispersing wolves were much more cautious about crossing highways than resident wolves. Wolves preferred to establish den sites near the center of their territory. Within that inner core they selected for areas with lower road densities, and most dens were dug into steep banks with sandy soils. They appeared to be more tolerant of roads and human disturbance at rendezvous sites than at den sites. Most rendezvous sites were established in lowland habitats within 50 m of a water source Wolves preferred to cross highways where they bisected large, homogeneous landscapes, especially lowland complexes. Wolf crossings were more likely to occur in areas providing greater visibility and ease of travel. A model was developed to identify "high", "moderate", and "low potential wolf crossing sites" in highway projects. The full impact of the US 53 construction project on wolves cannot be determined as of yet. Future increases in traffic volume, speed limits, and/or human development along the US 53 corridor could result in more serious impacts than found to date.
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