Wednesday, January 29, 2014

The Great Arctic Migration

The National Wildlife Refuge System plays a critical role in providing wintering grounds and staging areas for the Great Arctic Migrations. Before I go any further, I must say that I love winter for this very reason. I love all things Arctic and when the Arctic can come to me, so much the better! If you are not into cold weather then this is not the blog post for you. Stop reading now.  But if you love it as much as I do, carry on...

Ice wall at the high tide line.
Coastal Delaware River at Broadkill Beach near Primehook NWR

National Wildlife Refuges are some of my most favorite places to visit, no matter where I am in the country. Those of us lucky enough to live beneath the immense Atlantic Flyway have dozens of beautiful wildlife refuges across coastal areas in NY, NJ, DE, MD, and VA to visit. Considering the   Arctic nearly empties of its birds for the long polar winter, and that almost a third of these great migratory waves of ducks, swans, geese, loons, shorebirds, waders, passerines, and raptors use the Atlantic Flyway in their travels, well - we're in business!

Sharp polar winds raise the neck feathers on a watchful snow goose while its flock mates (blue morph included).

Most Arctic birds inhabit wetlands, finding food, claiming breeding territory, and enjoying a measure of safety in the vast northern system of marshes, ponds, lakes, bogs, and coastal regions. Come the brutal cold of winter, however, ice freezes up and food is inaccessible. Land hunters such as fox, wolf, bear, mink, fisher, and in the southern taiga, lynx take to the frozen lakes to hunt. Lush aquatic plants and seed-bearing grasses are sealed away by ice and cold and darkness. It's time to go!

The Great Migrations begin as early as late August for some species, and is complete in the Mid-Atlantic area by November.  Some Arctic migrants stop-over here and continue moving south, with a few species of terns, sandpipers, and sanderlings traveling incredible distances to South America!

Emily scans Shearness Pond at Bombay Hook DE for Arctic visitors. 

The story of the National Refuge System is one of great pride for American conservation. Avian species that only a few generations ago were in danger of extinction are now abundant and growing in population. Due in no small part to the extensive system of managed and protected refuges, we can now look out over our winter coastal landscape and enjoy the sights and sounds of great flocks of birds.

Tundra-like landscapes with open water leads and abundant food attract millions of arctic birds.

It takes a hardy naturalist to venture out in Arctic-like conditions, and this year has served up plenty of single-digit, brutally cold days and nights, but how exciting that our bitter winter is the perfect weather for exciting polar events! This year an amazing irruption of snowy owls swept into our region and (for the bundled and determined birders of the Mid-Atlantic) sightings were plentiful. Project SNOWstorm rapidly deployed a successful social media fundraising campaign  to purchase dozens of owl-sized transponders and within weeks their goal was reached - and exceeded! Many snowies were trapped from Wisconsin to New Jersey, and fitted with solar-powered GPS transponders. Donors and citizen scientists are able to follow their movements on the website, as the owls 'check-in.'  Following the owls will teach us much about their hunting routines and preferences, where they rest and when  they are active, and above all, give us a window into the lives of these creatures for which we know surprisingly very little. Check out Project SNOWstorm at

One of several  Snowy Owls we saw in one day along the Delaware Coast. Primehook NWR and Broadkill Beach, DE.

What's an irruption? 
This year's impressive snowy owl irruption may be the result of a large number of young owls being hatched and surviving the short Arctic summer, due in part to the high population of lemmings this year. Like many prey animals, lemming populations cycle up and down over years and decades.  Arctic biologists this summer observed the owl's ground nests ringed with dead lemmings indicating the top of the cycle. Low populations of lemmings in the down cycle often resulting in no breeding at all for snowies in some years. It is not uncommon to have occasional snowy owl sightings during the Mid-Atlantic coastal winter, but this year has been spectacular!

The horned lark population swells with Arctic flocks working across plains, fields, and pastures. Common at all refuges where food plots, grain fields, and meadows are maintained for winter foraging.

A family group of tundra swans  rest in the winter sun at Bombay Hook NWR, DE.
Without the safety of a large flock, this group is using the open expanse of ice
to provide a sight-line for approaching predators.

How do they 'know' to come south?
Some wonder if the birds "knew" we were in for a harsh winter. Arctic birds are sensitive to three environmental cues: food supply, barometric pressures (foretelling changes in weather patterns), and length of day (photoperiod). In response to a combination of cues, some species migrate sooner or later than others. Fall waterfowl migrations, spectacular for us, are generally not as risky as the return trip. Come spring timing is critical. It is not unusual for entire breeding grounds, crowded with returning birds, to experience the cruelty of a lingering winter. Nests on low patches of ground are easily flooded, and sitting birds on eggs are at the mercy of ground hunters when ice persists. Most arctic species hatch precocial young: babies that are ready to run and hide as soon as they hatch. But if hunters find an entire nest of eggs unguarded, the whole clutch will be destroyed.   
Roger and Donna West with my daughter Emily celebrate a fantastic owling day!


I keep a few Arctic field guides and natural history books (well, maybe more than a few) on my shelves at home. In winter, they are all off the shelf! These are two I really like, and on snow days and rainy weekends I re-read them. Someday, I'll make it the Arctic. But until then I am enjoying every day the Arctic comes to me! 

Pielou, E.C. (1994) A Naturalist's Guide to the Arctic. University of Chicago.

Sale, R. (2006) A Complete Guide to Arctic Wildlife. Firefly Books, Buffalo, NY.

This post is dedicated to the snowy owl known as 'Philly' who 'checked out' today at Philadelphia International Airport. Unfortunately, the arctic-like landscapes of airports attract young snowy owls, unfamiliar with planes and traffic, and many, like Philly, are killed before they can be safely relocated. Rest in the Great Tundra Above, young owl.

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