YEAR 1 - Big Sur Coast Highway Volunteer Roadkill Survey

John Smiley 831-667-2543
Big Creek Reserve, Big Sur CA 93920
(this page created on 2-11-02)

 Current results (as of 11-01) of the Big Sur Road Kill Survey are summarized as follows:
Summary: The purpose of this survey is to (1) help identify and locate roadkill "hot spots" that may correspond with wildlife corridors, (2) to illustrate the magnitude of roadkill within the corridor, (3) to determine the diversity of species affected, and (4) provide useful information and guidance for the Big Sur Coast Highway Management Plan. Approximately 20 people participated in the survey, and they reported approximately 160 roadkill sightings between October 2000 and October 2001. Reported sightings included at least 24 species of mammals and birds, including bobcats, coyotes, foxes, deer, raccoons, opossums, turkeys, and wild pigs as well as many smaller species. There were two distinct seasonal peaks, one in late spring consisting of mostly smaller animal species, and another larger peak in late summer, including larger as well as smaller species. Some Coast Highway "neighborhoods" had higher frequencies of roadkill than others, and these seemed to correspond to traffic speed or some other correlate of the terrain, with reduced kill on rugged, winding parts of the highway. Close examination of the reported locations of roadkill revealed concentrations in certain areas, suggesting that it may be fruitful to concentrate further investigation and possible mitigation in a few more restricted spots. These "hotspots" tend to be straightaways with high traffic speed and areas of productive habitat on both sides of the road, especially near streams or springs. Some spots such as Hurricane Point are an exception to this trend, however. More information is needed, as one year is not enough to detect inter-annual variations, and we need more observations to characterize areas where possible re mediation can be enacted.
Contents and Links:
Survey Description and Methods
Excel data file

Kill reporting by neighborhood
Identification of "hotspots"
Species Lists
List of candidate "hotspots"
Coast Highway Management Plan


Roadkill reporting by neighborhood The graph below summarizes the roadkill reported from 12 "neighborhoods" along the coast. Several reporting biases may be present. For instance, the paucity of roadkill in the extreme north may reflect a lack of reporting as no small animals were reported, and Big Sur residents may not realize that those areas were included in the survey. However, between Pacific Valley and Garrapata Coast the reporting is probably fairly even, with perhaps a trend of more reporting to the north. Thus, the reduced roadkill shown for the Lucia Coast and the Partington Coast probably represents a true reduction in the kill rate, suggesting that these neighborhoods are safer for wildlife with respect to being killed by vehicles. One possible explanation for these results is that these two neighborhoods are characterized by winding curves and somewhat reduced traffic speeds. Another is that the habitats in these neighborhoods include more rocky, steep terrain than in adjacent areas, and may be less desirable foraging and hunting areas for wildlife.

Seasonality This graph summarizes kill rates by month, illustrating the seasonal nature roadkill. As most reporting is by Big Sur residents there should be little bias in reporting effort as a function of season. Clearly there are two peaks in roadkill, one consisting primarily of smaller animals in the late spring and the other of larger and smaller animals in late summer

Identification of "hotspots" The 3 graphs below show each roadkill event as a separate dot, unless there are 2 or more at the same milepost. Then the number of kills is shown for that spot. These graphs aid in pinpointing "hotspots" where multiple kills were reported from a small area. We have tentatively identified 12 "hotspots" or candidate areas within which to look more closely (see key for full names). These hotspots correspond with most of the 18 hotspots identified in the Corridor Intrinsic Qualities Inventory (Parsons Tranportation Group 2002) using different selection criteria on the same data.

Acknowledgements The coast highway roadkill survey is a partnership between Caltrans, the Parsons Transportation Group consulting firm, UC Big Creek Reserve, and volunteer community members. Aileen Loe of Caltrans provided consistent encouragement and support. Adam Ballard of Parsons compiled most of the data from a variety of sources including handwritten notes, phone messages, and emails. Special thanks go to Big Sur CHP officer Frank Packard for his consistent and careful recording of roadkill observations.