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Text Box:    Human population growth in Arizona is exploding   at an alarming rate.  Projections are for over 15 million   residents by 2050.  This poses significant impact to our   natural environment.



Arizona’s wildlife is facing unique and overwhelming threats for the 21st century that can be summed up in three words, human population growth.  Maricopa Association of Governments projects an explosion of 17,000 people living cheek to jowl in Arizona by 2050. Already Arizona’s population exceeds 6million.





Fig 1



A large part of the state’s natural environment is projected to be smothered by a huge megalopolis extending from the Mexican border to Flagstaff and Las Vegas. Anyone who has traveled this corridor in the last few years has witnessed the explosive human growth in this portion of the state. Smaller, but no less disastrous to wildlife, human growth will also occur east to west along the I-40 and I-10 corridors.





Text Box:    Arizona as a Pass through State for goods coming from California ports to much of the U.S.
















Besides the obvious destruction of natural environments, by such infrastructure as buildings and urban areas, this unprecedented growth will impact wildlife in numerous and not always obvious ways.  For instance, canals carrying the life blood of the cities form impassable barriers or death traps to many species. Crossings for wildlife are often inadequate in number and size.


Text Box:    Canals cause serious barriers to wildlife movements.


fig 2


Some attempts have been made to providepassage for wildlife but the overpasses are too few and too narrow to provide good connectivity across



The changed way we use water has dried up rivers, streams and springs creating stress on wildlife during hot times of the year.

Text Box:    Some management activities such as water catchments   have been successfully implemented to mitigate the   needs of wildlife.    Text Box:    There are many ways that habitat fragmentation can influence wildlife for instance, food, cover, and water.  These are different at different times of the year.












Our roadways continuously kill millions of vertebrates yearly.  Smudges of fur are so common on Arizona’s roadways that we don’t even think about them. Over time, with increasing traffic, roadways have also created barriers that most animals can not pass, creating fragmented habitats. This is analogous to a person being restricted to a city, then to their house, then a room in the house, then a closet.  Somewhere in that process one will find it difficult to make a living.  That is what is happening to Arizona’s wildlife.  They are being squeezed into smaller and smaller areas where they can not maintain population viability.


Already Research Branch’s telemetry data from a variety of species show the same picture.  Animals come up to roadways, but do not cross.


Text Box:     Pronghorn do not cross major roadways thereby blocking their movements and fragmenting their populations.

Text Box:      Here again elk movements follow the same pattern being restricted by highways.  The few that are able to cross may   pose a danger to themselves and to commuters.















Text Box:    Bighorn sheep movements are also inhibited by roads and   highways in the same way that the Colorado River acts as   a natural barrier.  Again, there is concern that habitats and   populations are becoming fragmented for bighorn sheep.    Text Box:    Mule deer movement data follows the same pattern as previous examples rarely cross roads and highways. Over time, their populations will become fragmented and isolated.















Of course, some species, such as bighorn sheep and pronghorn, are more sensitive, but even with others, such as deer, traffic volumes in excess of 4 to 10 thousand vehicles/day becomes an almost complete barrier, a moving fence.  Just try to get across I-10 on a normal day to see what a crossing animal experiences.  The few that are adventurous risk ending up as bloody splotches on the road, thereby eliminating the most adventurous animals from the population.  This mortality exacerbates population fragmentation and restricted gene flow, thereby hastening wildlife population declines and even extinctions.

Text Box:      Active management strategies are needed to reduce   these types of incidents.

Fig 3











Roads and urban areas aren’t the only factors fragmenting Arizona’s habitats. Railroads also present barriers to wildlife.  Many single track railways now move a train every 15 minutes.  Double tracking will only exacerbate this “moving fence” barrier to wildlife.

Text Box:    Result of unmanaged crossing structures for the safe passage of wildlife.

Text Box:    Railways are not only dangerous for wildlife to cross  but also act as barriers to wildlife connectivity.









Agriculture has transformed wildlife habitat over large expanses of Arizona.  Although some crops provide food for some species, generally agricultural monocultures are not highly productive habitats for native species.  In addition, livestock carry diseases that are deadly for some.  For instance, domestic goats introduced contagious ecthyma to the desert bighorn sheep population in the Silverbell Mountains recently causing a large die off.


Text Box:    Agriculture lands convert huge   amounts of wildlife habitat.



Text Box:    Domestic animals carry disease to wildlife thereby detrimentally influencing the health of wild sheep populations.










Off highway vehicle use is fun, so much so, that its incidence is exploding.  Besides destroying vegetation and wildlife habitat the noise and activity of ATVs has an undoubted, but largely unknown, impact on wildlife.

Text Box:   More information is needed about the effects of OHV use on wildlife and their habitats.












Even such “passive” activities as hiking and nature walks create disturbance to some species. It is possible to love some species to death simply by getting too close to them too frequently. Some species can habituate to human presence, while others cannot.



Text Box:      Invasive species can be big and small like these quagga mussels that are small as a dime and can be transported between lakes in the boats.

Invasive Species tend to follow human activities, usually along roadways where seeds are carried by vehicles, or the outback where seeds are carried by hikers or domestic animals and even through our waterways when unwanted species are spread by boaters.

So Arizona's wildlife is embattled on numerous fronts, not all of them noted above.  The question is , what can be done about it?






Text Box:    Isolated islands of habitat in a sea of   development are not the answer.

Text Box:    Wildlife are not always able to adapt   at the speed of development pressure.













First, is the recognition that business as usual will not do.  We need 21st century answers for 21st century problems.  The Arizona Game and Fish Department is tackling these problems on many fronts, not the least important being research.  Below are a few examples.

The Department’s award winning research on State Route 260 has revealed several insights into how to safely move large animals across highways.  Seventeen bridge structures are proposed for about 13 miles of highway east of Payson.  Researchers monitored several of these already built crossing structures using video cameras to find out how animals reacted to then. 

Text Box:      East and West under passes…..









They found that several species of wildlife used the underpasses, but the design of the underpasses influenced how much they were used.  An underpass with concrete sided walls (West Underpass) was used much less than a nearby one (East Underpass) with natural slopes.  Video showed elk standing in the underpass entrance looking up at the top of the concrete wall, apparently looking for lurking predators.


Text Box: 	  Wildlife underpass	Wildlife species recorded on videotape  		Elk	 WT deer	Mule deer	 Coyote	Grey Fox	Raccoon	Other	All      No. animals on  video	West Little Green Valley               	2,179	198	9	14	15	5	146	2,445  	East Little Green Valley              	3,789	279	2	91	49	24	248	4,482  	Pedestrian-Wildlife  	1,098	965	66	45	127	168	71	2,455  	Wildlife 2   	1,743	93	798	27	55	20	136	2,778  	Wildlife 3 	125	145	90	2	2	99	24	487  	Indian Gardens	1,398	286	2	21	4	17	461	2,189  	Total 	10,332	1,996	967	200	252	333	1,084	15,134   No. crossing in underpass	West Little Green Valley            	1,626	30	0	5	10	5	143	1,819  	East Little Green Valley              	2,927	42	0	23	27	24	256	3,299  	Pedestrian-Wildlife  	789	660	37	24	78	68	16	1,672  	Wildlife 2   	1,160	46	647	9	35	9	83	1,989  	Wildlife 3  	33	116	72	2	2	98	18	341  	Indian Gardens	1,295	174	2	14	4	14	341	1,844  	Total 	7,830	1,068	758	77	156	218	857	10,216       Passage rate 	West Little Green Valley      	0.71	0.11	-	0.67	0.67	1.00	0.83	0.67  	East Little Green Valley              	0.71	0.06	-	0.22	0.58	1.00	0.90	0.58  	Pedestrian-Wildlife    	0.68	0.51	0.42	0.28	0.64	0.57	0.10	0.46  	Wildlife 2         	0.48	0.27	0.61	0.55	0.59	0.35	0.53	0.48  	Wildlife 3         	0.20	0.96	0.61	-	-	0.90	0.45	0.62  	Indian Gardens 	0.83	0.44	-	0.67	1.00	0.67	0.57	0.78  	Mean passage rate	0.61	0.39	0.55	0.46	0.70	0.75	0.56	0.58      Number of animals recorded on videotape, crossing through underpasses and passage rates by species for six wildlife underpasses, determined from video surveillance 2002-2008, State Route 260, Arizona.

Number of animals recorded on videotape, crossing through underpasses and passage rates by species for six wildlife underpasses, determined from video surveillance 2002-2008, State Route 260, Arizona.


GPS tracking collars showed that elk did not cross highways ubiquitously, but had preferred crossing locations.



Text Box:    This figure demonstrates that elk do not cross highways randomly but have definite preferred crossing areas.











Text Box:    Elk captured to collar with a satellite transmitter.

Researchers also found that where traffic lanes were widely separated and required two widely separated underpasses with an intervening atrium, those that were in a straight alignment were used more than those that were offset.  Presumably this disparity was explained by an approaching animal’s ability to see through the underpasses.


  Locations of GPS telemetered elk along Highway 260




Researchers also found that crossing structures were relatively ineffective unless combined with funnel fencing that kept animals from crossing at grade and funneled them to crossing underpasses.
















influence of Traffic Levels on Elk - Highway and Wildlife Underpass


One of the most important findings related to traffic volume.  The higher the traffic volume the less animals (elk) crossed highways. However, once funnel fences were installed and the animals learned to use them, they were not deterred from crossing the highway safely.  Thus two objectives are met by crossing structures with fencing, motorist/wildlife safety and eliminating the barrier effect of the highway to animals.









A similar pattern to elk was shown for white tailed deer.  They are much more sensitive to roadway disturbance and tended to avoid crossing SR 260.  However, after funnel fences were added to the crossing structures their crossing rate quadrupled.







Besides video monitoring to tell us how effective crossing structures are, the Department is investigating other innovative techniques, such as the automated crosswalk on SR 260. This system detects animals using IR cameras and military grade target acquisition software and then automatically turns on warning signs alerting motorists to animals crossing the roadway ahead

Text Box:    Schematic of an automatic detection system.  Animals are detected   by IR video I the detection zone and flashing signs are turned on   the alert motorists.  Text Box:      Flashing warning sign of the automatic detection system.









No one knows yet how to get desert bighorn sheep and pronghorn safely across highways, but ADOT in cooperation with the Department, is in the process of building three overpasses (the sheep go over the highway) on US 93, just south of Hoover Dam, which we think will work.  Once built these overpasses will be monitored by the Department to see if indeed sheep adapt to them as well as elk did to the underpasses on SR 260. Similar research is being done on pronghorn along Hwy 89 to see if we can find a way to safely move pronghorn across highways.


Text Box:    Placement of sheep overpass cut through a ridge.










Simulation of sheep overpass on Highway 93

FIG 8 Text Box:    Tracking data from 3 bighorn sheep along highway 93 depicting where sheep approach the highway which were good locations for crossing structures.









This is not a complete list of the Research the Department is involved in, but it gives you an idea of the innovative approaches we are using to make highways safer for motorists and wildlife.

Besides Research, the Department is heavily involved in identifying areas important to wildlife.  Working with several external partners, we produced a statewide map of Linkage Zones, or areas important for linking one large, undisturbed habitat block with another.  These Linkage Zones are made available to a host of transportation, land management agency, county, municipal and development planners to ensure green connectivity is included in their gray connectivity plans.

Text Box:    Map of potential wildlife linkage zones identified by the   Wildlife Linkages Working Group.  Text Box:




















The Department is also engaged in defining areas of high or important areas of species diversity.  All of these tools will shortly be available to planners on-line for inclusion in their development plans.  Hence, wildlife concerns, that have previously been excluded from development plans, will now beincluded.

With the recent emphasis on alternative energy, Arizona’s solar and wind resources are being investigated for development.  While there are environmental advantages to alternative energy sources, there are also impacts to wildlife.  The Department is involved with a host of cooperators to ensure that these types of developments have minimal impact to wildlife.

Text Box:


The Department is cooperating and partnering with a wide variety of external customers and publics to ensure that the Department’s mission to conserve, enhance and restore wildlife during the challenging times just ahead is realized. 











For more information contact:

Ray Schweinsburg, Ph.D., Arizona Game and Fish Department

5000 W. Carefree Highway Phoenix, AZ 85086-5000

Phone: (623) 236-7251 E-mail:


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