NJMC staffer Jim Wright, who keeps this blog, also writes a column every other Thursday for The South Bergenite. His latest, about a most unusual sign at DeKorte, is below:

   It might just be one of the strangest road signs in America. It’s located at DeKorte Park in Lyndhurst, and it only goes up once or twice a summer.

  The sign simply says, “Swallow Alert — Proceed with Caution.”

  That’s the New Jersey Meadowlands Commission’s way of warning drivers that the swallows are flying low in search of insects, and people should reduce their speed. We also post the sign on the Meadowlands Nature Blog, meadowblog.net, to let readers know in advance of coming to DeKorte.

  If you are a really savvy naturalist, you know the sign also means you should get out your raingear — but more on that later.

Rest of the column follows.

  Before we came up with the “Swallow Alert” sign last year, the commission used to send out e-mail alerts, warning staff to drive carefully when the small birds were particularly active. The only problem was, visitors to DeKorte Park weren’t getting the message.

  So now we post the sign instead, and we do so rarely because the swallows don’t stay here all that long, and they don’t fly low that often.  They migrate from points south in early spring, build their nests, have young, and then head south by mid-summer.

   If you don’t care about these graceful fliers, you should. They are mosquito-eating machines.

   The tree swallows — the graceful white-and-iridescent-blue fliers — build their nests in those wooden boxes you see in the marsh at DeKorte Park ,and elsewhere in the Meadowlands. The barn swallows — slightly darker blue, with red bandanas around their necks — like to make their nests of mud pellets. They place the nests in barns, under bridges or (in the case of DeKorte Park) under the Marshview Pavilion, the flying-saucer-like building that juts out in the marsh.

   Most of the Meadowlands District’s well-publicized tree swallows have already finished nesting and are getting ready to head south if they haven’t left already.  The barn swallows are starting to pack their bags as well. Last week they were the kings of the low-fliers, zigzagging at lightning speed across DeKorte’s parking lots and roadways in search of a quick meal. The “Swallow Alert” sign came out shortly thereafter.

   For the savvy nature-lover, the sign packs another message as well: Rain is on the way, if it isn’t already here. In fact, according to NJMC naturalist Gabrielle Bennett-Meany, who came up with the e-mail alerts, there’s an old weather saying that goes, “Low flies the swallow, rain to follow.”

   “The swallows are flying low to the ground for one simple reason,” says Gabrielle. “They are chasing bugs. When rain is approaching, the barometric pressure drops and the insects can’t fly very high. If the swallows want to eat, they’ve got to fly low to catch the insects.”

  Next time you see swallows flying low in DeKorte Park, drive extra carefully — and get out your umbrella.