Date of this Version
Huijser, M.P., Gunson, K.E., & Fairbank, E.R. (2017) "Effectiveness of Chain Link Turtle Fence and Culverts in Reducing Turtle Mortality and Providing Connectivity along U.S. Hwy 83, Valentine National Wildlife Refuge, Nebraska, USA" Nebraska Department of Transportation Research Report 4W6072.
We evaluated the effectiveness of existing turtle fences through collecting and analyzing turtle mortality data along U.S. Hwy 83, in and around Valentine National Wildlife Refuge, Nebraska, USA. We also investigated the level of connectivity for turtles provided through the culverts that were originally designed to pass water through a capture-mark-recapture experiment. While fenced valley sections had 33.1% fewer turtle observations than unfenced valley sections, the difference was not significant. However, we think that the effectiveness of the fence can be improved through fence repairs, other modifications of the fences, vegetation maintenance, and extending the length of the fences. Four of the five turtle species present in the study area used the culverts: common snapping turtle, painted turtle, Blanding’s turtle, and yellow mud turtle. However, we did not record ornate box turtle using the culverts. The culverts appear to have only provided marginal connectivity (7%) for the turtles that were interested in crossing the highway between 7 June and 30 September 2016. Assuming all turtles that passed the culverts in this period were originally marked, connectivity was still only 44%. We suggest implementing safe crossing opportunities (i.e. culverts or bridges) specifically designed for turtles, locating the culverts and bridges at intervals based on the home range size of the turtles, and maintaining the vegetation at the culverts and bridges so that they do not block turtle access to the crossings.