Wildlife Mortality and Corridor Use near Highway 77,
Oro Valley to Catalina, Pima County, Arizona
Desert tortoise about to cross a road in Tucson, AZ.
December 12, 2006
Elissa Ostergaard, Urban Wildlife Specialist
Arizona Game and Fish Department
Tucson Regional Office
555 N. Greasewood Road
Tucson, AZ 85745
Wildlife Mortality Report, Highway 77, AZ 12/22/2006
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Background
The Arizona Game and Fish Department’s mission is “To conserve, enhance, and restore Arizona’s
wildlife resources and habitats through aggressive protection and management programs…” Road
mortality is a frequent cause of death for wildlife. Recording the species, location and date of roadkilled wildlife is one way to determine where wildlife is attempting to cross roads. Areas of
frequent wildlife mortality may then be targeted for additional data collection or structures to
facilitate wildlife crossings, such as specially designed culverts, overpasses or fencing, with the
ultimate goal of preserving Arizona’s wildlife.
The area of focus for this report is along Oracle Road between the northern boundary of the Tucson
city limits and Pinal County, in northeastern Pima County, Arizona (Figure 1). This area was
identified as a Potential Linkage Zone in the statewide wildlife linkages effort spearheaded by
Arizona Game and Fish Department (AGFD) and Arizona Department of Transportation (ADOT)
(Linkage 81, AGFD, ADOT, unpublished report). It was also identified as a Wildlife Corridor in
the Sonoran Desert Conservation Plan (Pima County 2006; Figure 1).
The Tucson basin is currently experiencing rapid urban expansion, particularly in the valley
bottoms and foothills. Many of the mountain ranges surrounding the basin are publicly owned and
managed, and are not likely to be converted to human uses. Wildlife species that live in rocky
foothills and/or mountainous areas were historically able to traverse the valleys relatively
unimpeded by roads, canals, railroad tracks, walls, and vehicles. For example, a genetic
comparison of desert tortoise (Gopherus agassizii) populations from nine mountain ranges in
southern Arizona concluded that an average of more than one tortoise per generation migrates to a
different mountain range to interbreed (Edwards et al. 2004). Mountain lions (Puma concolor),
currently fairly common in the mountains and foothills around Tucson, could become more isolated
as urban development restricts their ability to move between mountain ranges (Noss et al. 1996).
This document presents road mortality data collected opportunistically and a targeted road mortality
survey conducted in late summer and fall 2004 along Highway 77 in Pima County.
Methods
Opportunistic Road Mortality Reports
AGFD has collected opportunistic reports of road-killed wildlife since 1990 in southeast Arizona.
Dead wildlife data collected includes report or collision date and time, location, species and
sometimes gender. Emphasis was placed on collecting data for large game animals, including deer,
javelina, mountain lion, bighorn sheep, elk, black bear, and others, but reports for animals such as
coyote, raccoon, bobcat, coati, American badger and others are sometimes collected (as in Figure
2). Since these data are not collected on predetermined routes or on a routine basis, the mortalities
reported may be concentrated near areas of regular use by AGFD staff or others with an interest in
reporting wildlife road mortalities. In 2005 a new database (Salvage Permit and Road Kill
database) was created for storing road killed wildlife data, and all existing road mortality was
moved into the new database.
Wildlife Mortality Report, Highway 77, AZ 12/22/2006
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Since data from the road kill database were mapped, an additional two coyotes and two javelina
were reported dead along or near Oracle Road at approximately mile post markers (MP) 80, 84.5,
79.4, and at Tangerine Road ¼ mile west of Oracle Road, respectively.
2004 Road Mortality Surveys
Results
Opportunistic Road Mortality Reports
Between 1990 and October 9, 2006 there were a total of eight reported road killed mammals along
Highway 77 between Tangerine Road and Wilds Road, MP 81 and MP 86 (Figure 2). Another five
mammals were reported killed between MP 79 and MP 86 and along Tangerine Road between late
August and the date of this report, and are not included on the map (Table 1).
Table 1. Wildlife mortality reports from opportunistic sightings, Oracle Road, 1990-2006.
Date Reported
6/24/1997
4/26/1999
6/28/2005
7/11/2005
8/26/2006
8/30/2006
9/6/2006
10/9/2006
10/15/2006
10/27/2006
10/31/2006
11/3/2006
11/4/2006
Species
Deer
Deer
Deer
Am. Badger
Am. Badger
Coyote
Coyote
Raccoon
Coyote
Coyote
Coyote
Javelina
Javelina
Approx. Location
Oracle Rd, MP 85
Oracle Rd, MP 83.9
Oracle Rd, MP 81.6
Oracle Rd, MP 84
Oracle Rd, MP 84.8
Oracle Rd, MP 83.8
Oracle Rd, MP 85.1
Oracle Rd, MP 84.2
Tangerine Rd, ¼ mile W of Oracle Rd.
Oracle Rd, MP 84.6
Oracle Rd, MP 80
Oracle Rd, MP 82
Oracle Rd, MP 79.4
Road mortality reports collected opportunistically are likely to be biased towards large mammals
and concentrated in areas where people who report road-killed wildlife travel most often. Even
with their disadvantages, they can indicate where wildlife crosses roads, and if collected over a
number of years, these may be the best data available to help locating crossing sites. When
possible, they should be supplemented with additional animal movement observations before
investments are made in crossing infrastructure.
2004 Road Mortality Surveys
A total of 255 animals were found dead along Oracle road during 8 mortality surveys in 2004. The
majority were mammals (46%). Reptiles were the next most abundant at 26%, followed by birds
(17%) and amphibians (11%). Most of the mammals observed were small mammals such as
kangaroo rats and mice, but also included 9 bats. Large mammals including cottontails, coyotes,
skunks and foxes were also seen. Many animals, including some large mammals, were not
identifiable due to their condition, as well as the time between surveys.
Wildlife Mortality Report, Highway 77, AZ 12/22/2006
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Of all road-killed reptiles observed, most were snakes (52%). Snakes may be killed by cars most
frequently due to their abundance, long body shape and slow movements, and human attitudes
towards snakes. Lizards were 33% of the reptiles found, and 9 percent were turtles. Only one of
the six turtles could be identified to species as a desert tortoise. Desert tortoises can live at least 50
years, and road mortality of long-lived species can have a negative impact on the long-term viability
of populations due to low birth rates (Gibbs and Shriver 2002).
The majority of wildlife road mortalities for all species groups (birds, mammals, reptiles,
amphibians) occurred between MP 81 and Rancho Vistoso Boulevard (MP 82.8). This area is
adjacent to Catalina State Park to the east and is immediately north of the crossing of the Canada
del Oro wash under Oracle Road (MP 80.8). Thus, the area to the east is largely publicly owned
open space, and Big Wash occupies some of the adjacent large open area west of Oracle Road.
A secondary area of high mammal mortality occurred north of the Rancho Vistoso community
between MP 84 and 86. This area was characterized by rural development with a few small
businesses, churches, a school and a juvenile detention facility. Amphibians had a secondary area
of high mortality between markers 83 and 84.5. Amphibian mortality is likely associated with the
presence of breeding pools and/or areas of high insect activity, and they are known to move most
during the monsoon season to breed in pools and feed on insects before estivating for the winter.
Conclusions
The two sources of wildlife road mortality data indicate that wildlife are attempting to cross Oracle
Road in two distinct areas, and many times are not succeeding. These two areas are between MP 81
and MP 82, and MP 83.5 to MP 85.3. A more detailed evaluation of wildlife mortality locations
could help refine the preferred location for crossing structures. Development restrictions and
zoning regulations to maintain a wildlife corridor in this area the Santa Catalina Mountains to the
Tortolita Mountains would likely benefit wildlife.
Wildlife Mortality Report, Highway 77, AZ 12/22/2006
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Table 2. Wildlife found dead along Oracle Road during wildlife mortality surveys, July 8 –
October 27, 2004.
Genus
Birds
Callipepla
Campylorhynchus
Carpodacus
Chordeiles
Columba
Molothrus
Molothrus
Passer
Toxostoma
Zenaida
Zenaida
Species
Common Name
Class Sub-Type
Number
gambelii
brunneicapillus
mexicanus
acutipennis
livia
ater
sp.
domesticus
curvirostre
macroura
asiatica
Gambel's quail
Cactus wren
House finch
Lesser nighthawk
Rock dove
Brown-headed cowbird
Cowbird
House sparrow
Curve-billed thrasher
Mourning dove
White-winged dove
Unknown bird
Unknown sparrow
Mammals
Canis
Mephitis
Sylvilagus
Sylvilagus
Urocyon
Chaetodipus
Chaetodipus
Chaetodipus
Dipodomys
Dipodomys
Neotoma
Onychomys
Perognathus
Reithrodontomys
latrans
macroura
sp.
audubonii
cinereoargenteus
baileyi
penicillatus
intermedius
merriami
ordii
sp.
torridus
flavus
megalotis
Coyote
Hooded skunk
Cottontail
Desert cottontail
Gray fox
Bailey's pocket mouse
Desert pocket mouse
Rock pocket mouse
Merriam's kangaroo rat
Ord's kangaroo rat
Woodrat
Southern grasshopper mouse
Silky pocket mouse
Western harvest mouse
Bat
Desert kangaroo rat
Kangaroo rat
Mouse
Pocket gopher
Pocket mouse
Rodent
Fox
Skunk
Unknown large mammal
Unknown small mammal
Unknown mammal
Large Mammal
Large Mammal
Large Mammal
Large Mammal
Large Mammal
Small Mammal
Small Mammal
Small Mammal
Small Mammal
Small Mammal
Small Mammal
Small Mammal
Small Mammal
Small Mammal
Small Mammal
Small Mammal
Small Mammal
Small Mammal
Small Mammal
Small Mammal
Small Mammal
Large Mammal
Large Mammal
Large Mammal
Small Mammal
Unknown mammal
2
1
2
3
2
3
2
1
2
10
2
3
1
1
9
1
6
9
1
2
9
2
2
2
1
39
Amphibians
Bufo
Bufo
punctatus
alvarius
Red-spotted toad
Sonoran desert toad
Toad
Toad
2
19
1
1
1
2
1
1
1
1
1
4
4
8
1
Wildlife Mortality Report, Highway 77, AZ 12/22/2006
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Genus
Scaphiopus
Species
couchii
Common Name
Couch's spadefoot
Unknown toad
Class Sub-Type
Toad
Toad
Reptiles
Callisaurus
Crotalus
Crotalus
draconoides
scutulatus
atrox
Lizard
Snake
Snake
2
1
3
Gopherus
Lampropeltis
Masticophis
Masticophis
Phrynosoma
Phrynosoma
Pituophis
Pituophis
Rhinocheilus
Sceloporus
Thamnophis
Trimorphodon
Urosaurus
agassizii
getulus
flagellum
bilineatus
mcalli
solare
melanoleucus
melanoleucus
lecontei
magister
marcianus
biscutatus
ornatus
Zebra-tailed lizard
Mojave rattlesnake
Western diamondback
rattlesnake
Desert tortoise
California Kingsnake
Coachwhip
Sonoran whipsnake
Flat-tailed horned lizard
Regal horned lizard
Gophersnake
Sonoran gophersnake
Long-nosed snake
Desert spiny lizard
Checkered garter snake
Western lyresnake
Ornate tree lizard
Unknown lizard
Unknown snake
Unknown reptile
Unknown turtle
Turtle
Snake
Snake
Snake
Lizard
Lizard
Snake
Snake
Snake
Lizard
Snake
Snake
Lizard
Lizard
Snake
1
2
1
1
1
1
16
1
3
1
1
1
5
12
4
4
5
Turtle
Number
15
8
Table 3. Numbers of wildlife mortalities by class during road kill surveys in 2004 along
Oracle Road, MP 81-86.
Class Type
Bird
Mammal
Amphibian
Reptile
Total
Sub-Type
% of Class
Small Mammal
Large Mammal
Unknown Mammal
Toad
53 %
14 %
33 %
100 %
Lizard
Snake
Turtle
33 %
52 %
9%
Total Number
27
118
44
66
255
Wildlife Mortality Report, Highway 77, AZ 12/22/2006
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Literature Cited
Pima County. Sonoran Desert Conservation Plan: Biological Corridors and Critical Habitat Map.
http://www.co.pima.az.us/cmo/sdcp/PDF/BiologicalMap.pdf Accessed Nov. 2, 2006.
Arizona Game and Fish Department and Arizona Department of Transportation. Unpublished.
Arizona’s Wildlife Linkages. Arizona Department of Transportation and Arizona Game and Fish
Department, Phoenix, AZ.
Edwards, T., C.R. Schwalbe, D.E. Swann and C.S. Goldberg. 2004. Implications of Anthropogenic
Landscape Change on Inter-Population Movements of the Desert Tortoise (Gopherus agassizii).
Conservation Genetics 5(4):485-499.
Gibbs, James P. and Shriver, W. Gregory. 2002. Estimating the Effects of Road Mortality on Turtle
Populations. Conservation Biology 16 (6):1647-1652.
Ingraldi, M. and E. Ostergaard. 2006. Wildlife Mortality along Wildlife Corridors in the Tucson,
AZ Area. Poster presented at The Wildlife Society Annual Arizona-New Mexico Conference,
February 2006, Flagstaff, AZ,
Reed F. Noss, Howard B. Quigley, Maurice G. Hornocker, Troy Merrill, Paul C. Paquet. 1996.
Conservation Biology and Carnivore Conservation in the Rocky Mountains. Conservation Biology
10(4):949-963.
Wildlife Mortality Report, Highway 77, AZ 12/22/2006
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Figures
Focus
Area
Figure 1. Sonoran Desert Conservation Plan, Biological Corridors and Critical Habitat Map.
Wildlife Mortality Report, Highway 77, AZ 12/22/2006
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MP 86
MP 85
MP 84
MP 83
MP 82
MP 81
MP 80
MP 79
Figure 2. Road mortality of wildlife in Oro Valley and Catalina near Highway 77 in Pima
County, 1990-2006.
Wildlife Mortality Report, Highway 77, AZ 12/22/2006
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Figure 3. Boundaries of 2004 road mortality surveys along Oracle Road/Highway 77 at Mile
Post Markers 81 and 86. Aerial photograph from Google Earth, Nov. 3, 2006.
Wildlife Mortality Report, Highway 77, AZ 12/22/2006
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N
Figure 4. Road mortality of mammals along Oracle Road/Highway 77 between MP 81-86,
August through October, 2004.
N
Figure 5. Road mortality of amphibians along Oracle Road/Highway 77 between MP 81-86,
August through October, 2004.
Wildlife Mortality Report, Highway 77, AZ 12/22/2006
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N
Figure 6. Road mortality of birds along Oracle Road/Highway 77 between MP 81-86, August
through October, 2004.
N
Figure 7. Road mortality of reptiles along Oracle Road/Highway 77 between MP 81-86,
August through October, 2004.