In the desert at night, it was easy to navigate to a kangaroo rat burrow I’d discovered earlier during the day.

Where, in this featureless desert, was that kangaroo rat den?

I asked myself that question as I drove along a washboard-surfaced dirt track in southern Arizona, the tunnel of my headlights half-illuminating the sloping sandy banks on either side where I’d spotted the telltale holes of a banner-tailed kangaroo rat earlier in the day. In the harsh sunlight of midmorning, the rat’s excavations had been easy to spot, showing up as black holes in the glaring hard-packed soil; but now, with my headlights flattening the relief, the holes had disappeared. Or so it seemed.

A loud beep sounded, and the text prompt on my GPS unit told me I was approaching the kangaroo rat’s den. I slowed down and watched the roadside, and a few yards and several seconds later a familiar tangle of mesquite trees and a cholla cactus skeleton that marked the rodent’s burrow appeared within my lights. I’d found my rats.

	The Garmin 530 has dual antennas, one for the GPS and the other for the powerful two-way radio. Here the main menu is displayed.

GPS units, Global Positioning Systems, have come of age, and today have real value for a photographer. I wouldn’t have said that years ago. Back then, because of military national security restrictions, the accuracy of a GPS unit was not more than a hundred yards or so. That type of accuracy is not of much use when you’re trying to find a little group of rodent holes in the middle of a desert or a hidden meadowlark’s nest in a vast field of alfalfa. Those accuracy restrictions have since been removed and today’s GPS units are accurate to within yards.

GPS units for field use work similarly to those that are used in cars. Most, if not all, GPS units come pre-installed with a US map supplying minimal detail. My unit, a Garmin Rino 530, had a fairly detailed US map that showed all the major roads and all the sizeable towns and cites, as well as the locations of most small, rural villages. More detailed maps for US regions, cities, streets, lakes, national parks, as well as for some foreign destinations, are also available. Most, if not all, GPS units can be downloaded with these maps from either SD cards or from a computer via a CD, DVD or a direct download.

	The display shows both a direct line of travel from my home to a Cabela’s store, and a detail of the factory-loaded map which shows the major highways in the area.

In a previous Photo Safaris column I referred to the joking line, "He who dies with the most toys wins," and my own desire to be in contention for the gold medal. I must confess that my GPS—besides being a very useful photographic accessory that I’ll discuss shortly—is a very neat "toy." On a recent cross-country trip, I kept the GPS on my truck’s dash and monitored direction, speed and progress. Since most GPS units can acquire a satellite signal through window glass they can be used inside a vehicle for basic navigation—or for very sophisticated navigation if a detailed city or street map has been downloaded.

To accurately navigate, a GPS unit must acquire information from three or more satellites. Doing so, a GPS can give longitude and latitude, elevation, direction and speed of travel. To accomplish this, the unit must have an unobstructed view of the sky, and the bigger that view is, the more satellites the unit can utilize to provide very accurate data. I found, for example, that my GPS provided a more accurate determination of my forward speed than the truck’s speedometer did.

In radio mode (above left), a status bar shows the strength of the satellite signal. Five bars indicates a maximum signal. The compass view (above right) shows direction of travel, elevation and speed. Because I was stationary, the speed indicator reads "0.0."

Because a clear view of the sky is needed, a GPS may work spottily in tree cover. On a hike through very tall ponderosa pines at 9,000 feet in Arizona’s Chiricahua Mountains, where I hoped to photograph the rare, talus-slope-dwelling twin-spotted rattlesnake, my GPS unit lost its signal several times, although when I reached openings where the sky was visible, the signal was reacquired quickly. Had I been lost—and had I marked the position of my truck before I started my hike (I wasn’t, and I didn’t)—I’d have been able to navigate out of the woods despite these limitations. By getting to a clearing and acquiring a signal, I could have dead-reckoned in the indicated direction back to my truck and fine-tuned my route at each clearing.

I cannot say a GPS unit has been essential to my survival, as for well over forty years I’ve navigated across our country’s highways and through field and forest fairly successfully without one. Indeed, even today I may not have considered getting a GPS unit if I had not had needed a better two-way radio than family-channels handset units. I needed a better system so that Mary Ann and I could keep in contact when exploring or shooting separately. When I learned that I could get a great two-way radio system that also included GPS as part of the unit, I was sold.

Of course, not every GPS unit has a walkie-talkie feature, but the two top-of-the-line Garmin units do. But what really sold me on the 520 and 530 series, Garmin’s best, was that both models had peer-to-peer positioning. If I could receive a radio signal from Mary, I’d have her GPS location as well and I could then navigate to her by simply clicking on her icon and selecting "Go To." With this feature, Mary and I could fan out across the countryside, looking for pumas in the rocky landscape of southern Chile or hidden pronghorn fawns in the rolling hill country of Wyoming. If either of us had success we could radio the other who could then hike or drive to that location with complete accuracy.

I’m not an expert on GPS systems and I haven’t done an exhaustive comparison of several units. I ended up buying Garmin’s top-of-the-line unit and my discussion must be limited to its features. I’d suspect that other units, offered by Garmin or Magellan or other manufacturers, have similar characteristics, although terminology and methods will likely differ.

	One of the waypoints I recorded was an elf owl’s roosting tree. At night I could find that location easily using GPS.

Perhaps the most useful feature of my GPS unit is its ability to mark waypoints, locations I’d like to return to later. When I find something of interest—a kangaroo rat den or a mountain bluebird nest hole, for example—I can mark the location by going to Main Menu and selecting Mark when the Mark Waypoint screen appears, typing in a description of up to ten characters. In southern Arizona I had waypoints for kangaroo rat den holes, rock piles where I’d found rattlesnakes, a canyon towhee nest, a well-hidden elf owl roosting hole, and a location for doing star trails. These waypoints, along with other data, can also be sent to another user on the same radio frequency.

Finding that nest or den or rock pile is easy. Navigating to the GPS’s Main Menu, I select Find, and under that submenu I select Waypoints. My list of waypoints appears, and I can toggle to the desired target. Selecting that waypoint, a new screen appears, with a choice for Map or Go To. Map shows the precise location of that waypoint on whatever map is installed, while Go To marks your present position and a line-of-sight direction of travel to that waypoint.

	From the Main Menu>Waypoints>Cabelas, I can either view a map that shows the location of my destination or I can route myself there by selecting Go To.

My GPS unit arrived just days before leaving for a trip out west, so I didn’t have much time to get to know the unit. On the way I visited a friend who had a photographic blind set up for greater prairie chickens. The blind was located in a remote rural area several miles from any main road that was marked on my factory-loaded US map. I hadn’t yet downloaded a more detailed map of the area, but could find my way from my friend’s home to his photo blind by using another neat feature, called TracBack. This feature records the route one travels, marking each turn exactly. Using it requires a bit more concentration than simply marking or finding a waypoint, as you must remember to turn on TracBack before you start, then name and record the route. However, once you’ve done this a couple of times, the procedure becomes imprinted and it’s easy to do.

Even without a more detailed map of the area, my recorded route followed the rural roads I traveled exactly, even though the dirt lanes were not showing on my

	Shooting greater prairie chickens from a friend’s blind was fun, but I wouldn’t have been able to find the blind again without my GPS to retrace the route I followed to get there.

GPS display. To return to the blind, I merely navigated back to the GPS’s main menu, selected Tracks>TracBack and toggled through to the desired location, which in this case was the prairie chicken blind. Positioning the GPS unit on my truck’s dashboard, I could follow the little triangular icon that marked my position and drive along this pre-recorded route, which showed up as a dotted line on the open map. Had I loaded a more detailed regional map, this dotted line would have been superimposed over the road itself. On several occasions, as an experiment, I’d purposefully miss a turn. The TracBack feature confirmed that error, showing that from my new position on the screen the correct route was now behind me. Backing up, I returned to the correct course.

Learning how to use the GPS unit was, I’ll admit, a bit frustrating, because I was unfamiliar with virtually all the terminology. I used Garmin’s instructional video as an introduction, and although the video wasn’t model specific, it gave me a pretty good handle on how a Garmin GPS unit worked. As training videos go, I think it’s the best I’ve ever viewed. The instructional booklet for my unit was a bit more frustrating, but I found that was because I skipped around and glossed over items. Once I had a general feel for the GPS, I reread the manual, finding the spots I’d missed or skipped, and everything began to coalesce. My greatest understanding of the unit, however, took place by simply playing with the different settings, toggling through the options and learning something new each time.

As I write this I must admit I’m a bit amused at how a piece of what I’d have considered non-essential equipment has quickly evolved into an extremely important part of my field gear, but that’s exactly what the GPS has become. While hiking in my usual haunts with it, I can record every nest I find as a waypoint without worrying that I’ll forget a location or a subject. Instead, bluebird 1, bluebird 2, oriole 1 and other names, not only identify the nest owner but also mark the exact location.

	Since the Garmin 530 has a two-way radio I can transmit a location to another user.

I do enjoy using a GPS. In Yellowstone, I had a new sense of confidence as I set off cross-country for some backcountry exploration. In the past my navigation was based upon the position of the sun and significant topographic features, but that didn’t mean that I might not return to a road hundreds of yards from where I’d parked my truck. Now, with GPS, I could hike back directly to my starting point. There’s an added safety component as well. In Yellowstone, for example, while Mary and I searched some thick cover in the backcountry for great gray owls, I spotted old, but very, very large, grizzly bear tracks in the snow. From a distance the tracks looked like someone had danced around the snow field wearing big snowshoes. I wasn’t very comfortable walking quietly through the woods looking for owls when we might surprise a bear. I radioed Mary and we both navigated safely back to our truck. I’m sure our GPS units will keep us from getting lost, too. In Denali, several years ago, my friends and I were almost hopelessly lost when a fog wiped out all distinguishing features of the tundra shortly after we stepped off the road to follow a herd of caribou. Only a small button compass one of my friends was wearing saved the day. Now, with GPS, exploring in foul weather won’t be an issue.

So I’m a believer now, a real convert. If you travel off the beaten path, if you have a need for marking specific locations or, like me, if you have a need to keep in contact with another’s position, you’ll find that a GPS unit is for you. Prices vary from about $150 to about $450 for the top models. For more information on GPS systems, check out these websites:
www.garmin.com
www.cabelas.com
www.magellangps.com/products

All images Copyright © Joe and Mary Ann McDonald