The NJMC's Jim Wright wrote this nature column about nesting Cliff Swallows for the current editions of The South Bergenite.

   Ever since the New Jersey Meadowlands Commission began a nesting-box program more than a decade ago, DeKorte Park has been  an attractive neighborhood for hundreds upon hundreds of Tree Swallows, those fast-flying iridescent-blue marvels that zip back and forth across the open water  in search of insects.
       This year, we have had a new type of swallow for a tenant – nesting Cliff Swallows. But these birds aren't taking up residence in the wooden nest boxes — they've made their own mud-walled homes under the Meadowlands Environmental Center’s Marshview Pavilion.
   “The Cliff Swallows are our ‘bird of the year’,” says NJMC Naturalist Gabrielle Bennett Meany. “We occasionally see these unusual birds as they pass through in the spring, but this is our first record of a nesting pair.”
    Bennett-Meany explains why it’s significant that the birds are nesting: “This is big news because these beautiful birds are listed on the state’s ‘birds of special concern’ list – which means that they warrant special attention because of evidence they’re vulnerable or in decline.”

   Since they nest under the
building, over the water,  they are safe from curious humans.
   How can you tell a Cliff Swallow from a Tree Swallow – or another DeKorte resident, the Barn Swallow?
Here’s my rule of thumb:

  If the flashy little bird has a shiny blue-green wings and it nests in a box over the water, it’s a Tree Swallow.
   If the little bird has dark blue wings with flashes of red on the neck and nests on the side of a building or underneath, it’s a Barn Swallow.
   And if you can see a peach-colored patch on its rump and a light patch above the bill, you’ve got a Cliff Swallow.     

   We first noticed the Cliff Swallows one rainy May morning, when the air was thick and hundreds of swallows were swooping across the payment  (?)  to nail low-flying bugs.
   When one of the swallows landed at my feet, I took a quick photo – and realized later the bird had that “headlight” on its forehead. A quick check of the bird guide served as confirmation: Cliff Swallow.
   A couple of weeks alter, bird-watcher Chris Takacs of Lyndhurst noticed Cliff Swallows gathering mud on the banks of the tidal impoundment by the NJMC Administration Building, and we knew we were in business.
   Since then, we have had several visitors come to DeKorte just to see our Cliff Swallows – that’s how unusual they are.
   Typically, Cliff Swallows nest in great numbers. It’s hard to tell if the Cliff Wwallows nesting this year are part of a vanguard, or just an aberration. We’ll just have to wait until next year to see what swallows spring brings.