The Mendenhall Wetlands are like a truck stop for migrating birds. They exit off their airborne interstate to take advantage of the snacks, of both the vertebrate and invertebrate variety, the lodgings and the opportunity to just refuel.
They arrive in waves by the thousands, beginning in early April and lasting into May. Some stay for only a day, others nest and raise young. For all, this nationally recognized important bird habitat is vital to their ability to thrive.
Mark Schwan, a retired fisheries biologist and Juneau Audubon Society president, has birded in the Juneau area for more than 30 years. He said the area, which might seem commonplace to Juneauites, is a regional scarcity for migrating birds.
"There's only a few places in Southeast Alaska that feed the needs of the birds like the wetlands," he said.
The wetlands area, officially called the Mendenhall Wetlands State Game Refuge, is one of two others in the region where birds, such as the Arctic Tern - which Schwan said travels perhaps the furthest, from South America - have an opportunity to replenish their drained energy stores. The only other areas providing similar habitat are the Stikine River Delta and the Yakutat Forelands.
"The most distant migrant is perhaps the Arctic Tern," he said. "They always come up as the 'marathon migrant.' That bird starts at Tierra del Fuego, on the southern tip of South America, and travels 24,000 miles to the interior of Alaska. Each year, that is how far they travel."
The tern may be the most impressive, stats-wise, but the species is only one of several hundred that arrive throughout the spring.
Waterfowl, such as ducks and geese, are the first, followed by scores of shorebirds, songbirds and even some migratory raptors, including Short-eared owls and Northern Harriers.
The Rufous Hummingbird, a summer resident in Juneau, winters in Mexico. The Golden Plover pauses here on its way to the Seward Peninsula.
"It's just what makes Alaska so cool," Schwan said. "We may see (these birds) on rare occasions, these birds that normally go way down into the Palearctic region, and come from the 'old world' such as Asia and Europe."
In a sense, he said, it's here where East meets West.
But what is it about these local wetlands that draws such a crowd?
Bob Armstrong, a local birding enthusiast, photographer, author and outdoorsman, said it's a combination of factors.
"Birds choose this area because of food, huge numbers of invertebrates, I think. And it's partly because of the large number of streams that empty out into the wetlands that creates this estuary-type of environment," he said.
Armstrong particularly enjoys watching the shorebirds. These long-legged and often thin-beaked birds arrive by the thousands beginning in mid-April through May.
"They're such characters, the shorebirds," he said. "How they feed, for instance. Some, like the Turnstones, do just what their name suggests, turning stones over and grabbing invertebrates underneath."
And at low tide, tiny flies go out to feed bravely on the algae. The returning tide, Armstrong said, traps the bugs for mere moments on the water's surface.
"Sandpipers will run around trying to catch them. That's fun to watch," he said.
In terms of observing birds, both experts agree the Mendenhall Wetlands are a superb place to choose, especially this time of year. A quiet place next to a slough is where Armstrong says he enjoys watching birds probing the muck.
Especially the Long-billed Dowitcher, with their 5-inch beak, who sniffs out food deep in the mud.
But life is not always quiet on the wetlands. Schwan said it's always exciting to see a bird of prey species, like a hunting Merlin (in the falcon family) or a Goshawk.
"During the spring migration we have these big, bouncing Northern Harriers that will fly low to the ground looking for small rodents," he said. "There's no mystery as to why a mass of gulls will take off as an eagle passes by. Just seeing the food chain at work, seeing that in the open is pretty exciting in the bird world."
Spring visitors to the Mendenhall Wetlands State Game Refuge are like large families on a road trip. Some pause only momentarily before moving on. Others stay a while, enjoy the scenery and sample the regional fare.
When it comes to viewing one of nature's natural phenomenon, now's the time.
"There are times when you can go out on the wetlands and see about every species of shorebird and every species of waterfowl in one day," Armstrong said. "Sometimes there are, with shorebirds in particular, numbers in the thousands. If you see 4,000 Western Sandpipers, then on another day you see another 4,000, they're probably not the same birds."
• Contact Outdoors editor Abby Lowell @ email@example.com.