Certainly, you can put your snow shovel and heavy winter coast away, spring has arrived! How do I know? Well, the first weekend of April was delightfully warm, sunny, and dry with air temperatures in the mid 60s to low 70s. It was a gorgeous spring weekend with not a storm cloud in sight!
A further sign was the opening of fog season. During the past weekend there was dense morning fog along the coast. Sandy Hook Bay was socked in with fog while areas just a short drive inland, such as Red Bank or Holmdel were basking in beautiful morning sunshine. Once cold ocean waters and a moist, warm layer of air riding above combine, a fog bank forms over the sea and is transported by the prevailing wind. If that wind is onshore, then fog will ride slightly inland. Usually sometime before noon the fog disappears just as mysteriously as it appeared.
(Northern Gannets dive like Ospreys when feeding. The birds pierce the water with the smallest amount of splash, like an Olympian performing the perfect dive)
The best sign of spring in Sandy Hook Bay, however, is when a good number of Ospreys arrive to their nesting platforms and the Gannets arrive on the scene to feed on fish in the bay. Well, guess what. They are here!
The Ospreys have been around for a bit now, and the Gannets have showed up by the hundreds on the bay side of the Hook around April 1. This is an amazing time when everything seems to come together for a few weeks to supply some early energy for coastal creatures with wings.
(Ospreys, swooping and plunging for fish, have always been a familiar site for residents of the Bay)
It all starts with the sun. The sun warms the water in the bay, and the sun thaws out the mud and soil in wetlands. Additionally, spring rains discharge nutrients and food into the water. All this activity helps to create vast populations of plankton in the water, which in turn helps to feed small fish, such s herring.
Plankton rich food in the bay, along with warmer water temperatures, will attract large schools of fish, such as Alewife, Blueback Herring and Shad, to enter into Sandy Hook Bay. For the past several weeks, these fish have been waiting patiently off the coast of New Jersey for just the right conditions to enter the bay, feed, and then head upstream to freshwater portions of the Hudson, Raritan, and Navesink rivers to spawn. In the past, the herring have always returned to Sandy Hook Bay when water temperatures hit 40 - 48 degrees F, usually around late March or early April. At this point, the water temperature in Sandy Hook Bay has responded to the warm air temperatures by rising to 48°F. Just as if someone has thrown a switch, the herring has arrived.
(Northern Gannets are birds of the cold North Atlantic, with breeding colonies in the far northeastern Canadian Maritimes)
Yet, before the herring can spawn, they have to get through a gauntlet of hungry birds. If you are not sure when the herring have arrived, look for the Gannets. These seabirds always alert people to the presence of the plankton-eating herring into the bay.
All of sudden, dozens of gannets have shown to feed. They plunge into the chilly waters of the bay like javelins from fifty feet or more in the sky only to quickly resurface, holding in their bill a herring. There never seems to be only one gannet diving for food. Maybe up to a hundred can gather in an instant as soon as the first fish is caught.
Watching these beautiful birds in action from the Fort Hancock section of the Hook catches your eye, as they gulp down foot-long fish. This action probably signals other birds too, since stiff competition for the herring seems to take place by other birds, such as gulls and Ospreys.
With the return of the Ospreys to the bay from their wintering home in the tropics, comes their search for food too. These large birds are hungry, and people don't call them fish hawks for nothing.
As some Ospreys begin the process of fixing up their nesting platforms with twigs and branches, other Ospreys are scanning the bay for an easy meal. Ospreys hunt by soaring over the bay, periodically hovering to scan the surface for large schooling fish, such as herring. Upon sight of its prey, the Osprey makes a spectacular dive from high above the water. Folding its wings tightly, the bird descends quickly and plunges feet first into the water, often submerging itself completely. To fly more smoothly after catching a fish, the bird will re-arrange the fish in its talons so the fish faces head first, thus presenting a more streamlined shape.
Ospreys usually hunt in the early morning or late afternoon perhaps because the light is best for sighting underwater prey. Ospreys also have feathers that are very oily for extra waterproofing as they plunge into the water. This makes them buoyant, so they cannot go deeper than about 3 feet below the surface. Their nostrils can close as they dive underwater.
The seasonal moment of the year when both Northern Gannets and Ospreys rule the sky over Sandy Hook Bay is a special time. Their appearance tends to correspond to the arrival of springtime fish migrants such as herring, shad, and Atlantic mackerel, and a sure sign for many coastal areas of the Northeast that spring has finally arrived.