By Vicky Runnoe,
Idaho Department of Fish and Game
The muffled "whump, whump, whump" of a helicopter passing overhead is a common sound over much of Idaho. Whether it is a Forest Service helicopter ferrying water to a forest fire or LifeFlight transporting a patient, helicopters have proven their worth time and again. Fish and Game has been relying on helicopters to survey fish and wildlife for many years.
Helicopters offer many advantages to the field of wildlife management. Large areas can be surveyed efficiently and quickly, and biologists are not limited by the availability of roads and trails. In addition, the low-level flight capabilities of a helicopter allow biologists to see animals that are simply too far away to be spotted from a road or trail or would otherwise be hidden by topography or vegetation.
Here in the Salmon Region, helicopters have been used to survey elk, deer, mountain goat, bighorn sheep, pronghorn, and sage grouse. During these surveys, sightings of other animals such as moose, mountain lion, wolf, or black bear are noted, providing documentation of a species' presence in certain areas. Helicopters are also used during capture operations to place radio collars on a number of big game species. Fisheries biologists even get the chance to take to the air to fly along regional waterways to count Chinook salmon redds ("nests" excavated in the stream gravel by the female into which eggs are laid) or stock fish in high mountain lakes.
These surveys generate important data about the wildlife populations surveyed. Population estimates for a herd of animals helps wildlife managers set seasons and tag quotas for hunters. Monitoring ratios of animals such as fawns/does or bucks/does provide information on reproduction in a deer herd as well as fawn survival. Determining the number of Chinook redds in a river stretch is important in monitoring overall health of the Chinook population in the region.
But the use of helicopters has its down sides. Animals can be stressed by the presence of a helicopter. Time in the air is very expensive and finding qualified and experienced pilots is becoming more difficult as many of these Vietnam-era pilots retire. In addition, and most importantly, low-level flying is dangerous. More than 50 Fish and Game employees have been involved in aircraft accidents; ten more have been killed. In spite of the dangers, helicopter surveys continue to provide wildlife managers with the best information to use in managing wildlife.
Aerial surveying and how it works
Flying around in a helicopter counting critters sounds like pretty easy duty. In fact, everything about an aerial survey requires careful planning. Before the chopper even leaves the ground, biologists have spent considerable time identifying target populations to be surveyed and objectives of the survey. They have also determined precise observation procedures to be used. Adequate sample sizes and survey designs are essential for obtaining valid results.
Safety is also addressed on the ground. Any Fish and Game employee who flies low-level flights is required to take an aircraft safety course sponsored by the Office of Aircraft Safety (OAS). This training must be renewed annually. In addition, all pilots and aircraft must be certified by OAS. Every helicopter is required to carry survival and first aid equipment as well as an Emergency Locator Beacon which can be used to help locate a downed aircraft. Flight following procedures are established prior to all flights and are required for any Fish and Game aerial survey work. During flight following, a dispatch center contacts the aircraft at pre-arranged intervals via radio or, in some cases, tracks aircraft with a satellite-based system. Should the dispatch center lose contact with an aircraft for more than 90 minutes, Search and Rescue efforts are initiated.
Once in the air over a survey location, the pilot follows standardized procedures to help ensure that the best data collection effort is conducted. This is where an experienced pilot is necessary. A ground speed of 40 - 50 mph is maintained at an altitude of 100 - 150 feet. Surveys begin at low elevations and move up, following elevation contours in steep terrain such as that in the Salmon Region. With the pilot following those protocols, the two observers in the helicopter can concentrate on their jobs. Having two sets of eyes to scan the ground helps in the spotting and counting of animals. Observers also determine the sex and age of animals and estimate the percent of vegetative and snow cover along with other habitat characteristics.
But differences in habitat and other conditions affect the ability of observers to actually see all the animals on the ground. This failure to observe all the animals present in a given area is called "visibility bias." Primary factors that contribute to visibility bias include number of animals present, density of vegetation, snow cover, and animal behavior. Not accounting for visibility bias can lead to underestimation simply because only some animals are observed under some conditions. For example, adult bull elk typically use dense cover and they occur in small groups. This decreases the chance that they will be seen and an uncorrected count will show fewer bulls than were actually present.
Because observers are only human after all, wildlife researchers in Idaho developed a "sightability model" that is now used to estimate elk populations in many western states. This model corrects and accounts for visibility bias in a big game survey. Sightability models are mathematical models that take into account a number of factors that affect aerial surveys. The first set of factors is observer factors. These factors are part of the reason that survey procedures must be strictly followed. Observer factors include aircraft type; survey area width; number of observers; and aircraft height and speed. All of these factors can be controlled by survey designs and procedures.
The second set of factors used in a sightability model is environmental factors. These factors can be measured, but not controlled. They include activity level of the animals; amount of snow cover; size of the group; and amount of vegetative cover. These factors are all important because they affect an observer's ability to see animals. Moving animals are easier to see and complete snow cover makes animals more visible. Large groups of animals are easier to spot, but areas with heavy forest cover can hide animals. When direct observations gathered during an aerial survey are corrected for both observer and environmental factors, population estimates become more accurate.
Sightability models are often dimly viewed by people who are skeptical of using "math" and "computers" to estimate animal populations. As Idaho's sightability model was being developed, a great deal of testing was done to insure accuracy of the model. Known populations of animals in specific areas were surveyed by biologists who did not know the actual population number. Use of the sightability model provided very accurate estimates of the actual number of animals present. The simple fact that this model has been adopted by many western states speaks to its validity as a wildlife management tool.
Aerial Surveys in the Salmon Region
Like other Fish and Game Regions, the Salmon Region uses helicopters extensively to survey big game. Because animals are more concentrated and snow cover improves ability to find animals, surveys are usually conducted during winter and early spring.
Elk herds are surveyed and the sightability model is used to provide an overall population estimate. On average, each big game management unit is surveyed for elk every 3-5 years depending upon budgets and other considerations.
The sightability model is also used with deer to help account for environmental factors. Aerial surveys for deer are done in the same representative areas each time a survey is conducted, often every year. This allows information to be gathered about population trends that are representative of larger areas. December flights focus upon fawn/doe and buck/doe ratios while early spring flights look at total deer numbers and fawn ratios to determine overall winter survival.
Bighorn sheep and mountain goats are typically surveyed every five years. Suitable habitat is surveyed to estimate a minimum population count. In addition, biologists determine the age and sex ratios of both species. Pronghorn surveys are conducted intermittently, usually in the late summer.
With all this flying around, it is no wonder that Fish and Game frequently gets questions about whether big game animals are stressed by the presence of a helicopter flying overhead. Biologists acknowledge that some stress probably occurs, but are quick to point out that they do everything possible to minimize stress to the animals. Animals are disturbed for only a few minutes and this disturbance represents an extremely small amount of an animal's year. In most cases, the animals in a given area may see a helicopter only once in 3 - 5 years. Data gathered by monitoring radio collared fawns does not show an increase in the deaths of these animals shortly after capture as would be expected if stress was causing the fawns to die. In addition, different species react differently to helicopters under different conditions. Sometimes elk simply remain bedded or continue grazing while observers gather data. Bighorn sheep and mountain goats tend to be more sensitive to disturbance, but no matter what the species, biologists make every effort to record the needed data as quickly as possible to minimize stress to the animals. As Tom Keegan, Regional Wildlife Manager, puts it "It's a balancing act. We have to balance disturbance to the animals and the risk to biologists' lives with our need to collect sound data."
Another balancing act is balancing the budget, especially as time in the air becomes more and more expensive. Overall, Idaho does significantly more aerial survey work compared to most other western states, mainly because of our rugged terrain. Back in 2002, it cost $560 for an hour of time in the helicopter with this amount including fuel as well as lodging and per diem for the pilot and his fueling crew. Today, this same hour of time has increased 30 percent to $726 and is likely to continue climbing. This 30 percent increase has far exceeded any increases in license and tag fees, meaning that biologists are being forced to fly fewer hours which, in turn, yields less management information.
And if the expense is not enough, many fish and wildlife agencies are beginning to face a shortage of experienced helicopter pilots. Many of those now flying are beginning to reach retirement age and few younger pilots are waiting in the wings. A number of the pilots who contract with Fish and Game have flown the same terrain with the same staff for years. They know their aircraft, the country, the staff, and the specific protocols necessary to do good aerial survey work. They are vitally important to the success of a Region's aerial survey program and trying to replace them is something biologists do not like to think about.
In spite of the difficulties associated with aerial surveys, the data they provide is vital to sound wildlife management. And sportsmen are the ultimate beneficiaries. Because helicopters allow access to large, remote, and rugged areas, biologists can obtain accurate estimates of populations of big game animals. This information allows biologists to be more precise in setting seasons and permit levels which results in maximum opportunity for hunters. Impacts of natural events such as forest fires or a harsh winter can be assessed, and seasons and permits adjusted accordingly and in a timely manner. Without information gathered by aerial surveys and population estimates derived from sightability modeling, biologists would be forced to be much more conservative when setting seasons. And for hunters, this would mean fewer opportunities and less time in the woods looking for that perfect animal. In spite of the negatives, aerial surveys remain the most efficient way for Fish and Game to gather the best data that ultimately makes Idaho such a great place to hunt.