Earth Matters: Bird migration

The Island Now

May is the peak of spring migration. About half the birds in North America migrate, and they are now on the move.

If you go out to a local park or preserve you might be lucky to spot some of the beautiful warblers in their bright breeding plumage (feathers). Many of these birds are only passing through on their way farther north, so this is the only window to spot them until the pass through again in the fall when many are known as “confusing fall warblers” because they are have molted out of breeding plumage and are fairly non-descript.

Migration is driven primarily by food resources. Generally, most of the birds leaving in the fall are insect or fruit eaters and most of the birds staying eat seeds. Spring migration comes in waves beginning in February with the return of Common Grackles and Red-wing Blackbird males.

The females, being sensible, don’t arrive until April and May. Ospreys and the first Egrets generally appear in late March. But the avalanche is mid-April through mid-May.

This year migration has been more sporadic due to the cold spring in the north and unfavorable winds. At the same time, birds are arriving from the south, some as far as the southern tip of South America, other birds that consider Long Island a great place for a winter vacation are leaving for the boreal forests and tundra of Canada.

These include feeder friends like Dark-eyed Juncos and White-throated Sparrows, along with many of the waterfowl we see on the bays and ponds over winter; Scaup, Buffleheads, Mergansers, and Long-tailed Ducks.

There are several different migration patterns from short, like local Robins who move gradually south as they exhaust local food resources, or birds that only move from higher to lower elevations.

Medium distance migrants may only go one to several states. Short and mid-distance migrations probably evolved as birds followed food resources. Long-distance migrants have dual citizenship here, and in the Caribbean, Central and South America.

Why birds get the urge to migrate vary and are not always completely understood. It can be triggered by a combination of changes in day length, lower temperatures, changes in food supplies, and genetic predisposition.

There are theories as to why long-distance migration evolved, most commonly thought that over thousands of years, birds expanded northward to take advantage of longer day length, less competition and greater abundance of insects.

As the glaciers of the ice age retreated, birds came even farther north. Their greater breeding success than their stay at home counterparts gradually changed the genetic dominance.

Exactly how bird migrate also holds some mysteries. It’s known that birds can get compass information from the sun, the stars, and by sensing the earth’s magnetic field.

They also get information from the position of the setting sun and from landmarks seen during the day. But how a first-year bird knows instinctively how to make a journey of hundreds or thousands of miles and exactly where to go is still unknown.

Most birds do the longest legs of their journeys at night and avid birders watch radar reports for favorable wind conditions and radar patterns of evening take off, hoping for a large “drop out” the next morning as birds set down and begin foraging to replenish the energy used in miles of flight.

Long Island is a global destination for birders with a wide variety of habitats drawing both shorebirds and woodland and field songbirds. Some favorite sites are currently closed due to the pandemic like Jones Beach West End, Sands Point Preserve, and Oceanside Marine Nature Study Area.

Other destinations like Alley Pond Park, Jamaica Bay Wildlife Refuge, and Hempstead Lake, Caumsett, and Heckscher State Parks with lists of over 200 species each, are open. There are also lots of local spots to see birds. A free ebird.org account allows you to go to Explore, type in Nassau County and click on the map.

You’ll see all the local birding spots where bird lists have been submitted. You can see the most recent sightings that will tell you what to look for. With a little effort, it’s possible to see over 200 species in a year – I’m at 157 right now.

Well stocked home feeder stations (seed, suet, mealworms, fruit) and a birdbath can allow you to see 40+ bird species a year without leaving home.

A bird guide and binoculars or a long lens attachment for your smartphone will allow you to expand your bird identification skills.

There are apps like Merlin that can give you identification tips and Facebook pages dedicated to bird identification. Once pandemic restrictions ease the seven Audubon chapters of Long Island will resume field trips, which is the best way to learn – go birding with someone who knows what they are looking at.

Birding is a fun and addicting hobby and living in a birding hot spot gives lots of opportunities to see many different and beautiful birds especially at this time of year.

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