From the Mountains to the Salt Lake

One of the great pleasures of the naturalist’s life is travel to locations where new habitats and species dazzle the brain. Our once a year trips to Salt Lake City, Utah, to visit family provide exposure to habitats that are quite different from those in the east. Two extremes are the high mountains and the Great Salt Lake.

When traveling from near sea level to high altitudes there is a problem with acclimation and thus strenuous activity is problematic. I have found a wonderful area in the high Uintas mountains near Kamas, Utah, where you can drive to 10,800 feet elevation and observe alpine ecology without much exercise. I show a photo of the side of Bald Mountain and adjacent meadows. When we were there in mid-September the ground was frozen in spots but there were still asters in bloom and two species of butterflies nectaring, Milbert’s tortoiseshell (shown in photo that feeds on stinging nettle as a caterpillar) and the Mormon fritillary. It is remarkable that butterflies can exist in such hostile surroundings, but for those that can survive the cold temperatures and short growing season, competition is minimal. Milbert’s tortoiseshell overwinters as an adult and accumulates an antifreeze (glycerol) in its tissues. The dark wing coloration facilitates basking to raise the body temperature in cool conditions.

A radically different habitat type is found only 60 miles away along the shores of the Great Salt Lake at about 4200 feet elevation. Since fresh water flows into the lake but leaves only by evaporation, a high salt content has built up to 4 to 28% (compare to sea water at 3.5%). Thus there are no fish; brine shrimp and brine flies (see photo) are the main aquatic organisms that provide food for a myriad of water birds. The easiest way to view the remarkable ecology of the lake is by driving along the causeway to Antelope Island (see photo I took from our plane). In case you tend to think about ecology as static, it is interesting to consider that the lake varies a lot in depth and size over time and only 15,000 years ago was 700 feet deeper (the Bonneville level). This fact is immediately obvious if you take a look at the nearby mountains and notice that there are several wave-cut benches (see photo with horizontal lines along the mountain slopes) showing exactly where the lake levels remained for sustained periods.

The number and variety of birds that either breed at or migrate through the salt lake area are remarkable. One of the most bizarre is the long-billed curlew with a truly impressive bill. It actually spends most of its time in dry fields in the western high plains, but can be found on the edges of water when migrating. This largest of our shorebirds uses its very long bill to probe for insects in grasslands. It is seen on the salt lake as it migrates to northern Mexico or the southern US.

The photo shown of a mixed group of birds along the shores of the Great Salt Lake illustrates some of the different types present during migration. The bulk of the individuals are spectacular avocets in their black and white non-breeding plumage. Avocets have a thin upturned bill that is used to sweep back and forth in shallow water to catch small invertebrates. They migrate to the eastern and western US coasts during winter. There are also a few black-necked stilts which have very long legs and a fine straight bill which they use to pick up small invertebrates in shallow water. There are several dark white-faced ibis present which probe in shallow aquatic and terrestrial habitats with a sturdy down-curved bill. These ibis breed near inland wetlands and migrate to the coasts in winter. There is one California gull which has a rather different life history from most gulls in that it breeds in the interior near lakes and marshes, but then migrates to the west coast in winter. Finally you will notice a number of small birds in the water which are red-necked phalaropes in non-breeding plumage. They often twirl around in a circle as they feed on small aquatic invertebrates at the surface. A closer view of the phalaropes is also shown. These tiny birds are present in huge numbers in September as they migrate from their breeding grounds in fresh water pools in the Arctic tundra to their wintering areas in the ocean off both coasts. If you encounter these tiny birds at sea as I have you can only marvel at their ability to survive the winter in such hostile surroundings.

The most remarkable aspect of observing birds along the Antelope Island causeway is that most of these birds are in the process of transit from their breeding grounds to wintering grounds, and their stories are all different. The Great Salt Lake is an immensely important stopover point for them to eat and re-fuel during their migration. So do not miss the opportunity to visit this amazing place if you are ever in Utah during bird migration.

Bill Dunson, Englewood, FL & Galax, VA
wdunson@comcast.net