One good tern…..

Barnegat Lighthouse

Of course the phrase above goes on to say, “ deserves another”, and today’s blog post centers around the search for tern species at Barnegat Lighthouse Jetty. We’ve visited the inlet between the lighthouse and Island Beach State Park for years in different seasons and each season brings with it a new assemblage of avian inhabitants. In summer, we expect mostly a limited variety of gulls and terns, so anything other than that is a bonus. Our first sighting of the day was in fact one of these outliers….an American oystercatcher.

The oystercatcher has been featured in Naturally Digital previously from our time down in the Sunshine State, but it is always a pleasure to find them here in Jersey. While not uncommon up here at this time of year, they tend to be hanging out on the islands in the bay, so to have one fly by in the inlet and offer up a decent photo-op is greatly appreciated.

But,,,, back to the terns. The first of the day was the one I most expected to find here during July. The Common Tern (Sterna hirundo) is a medium-sized seabird known for its graceful flight and striking appearance. It features a slender body, sharp pointed wings, and a forked tail, with a distinctive black cap on its head and a bright orange-red bill tipped in black. Common terns are highly migratory, spending their breeding season along temperate and subarctic coastlines like we find here in New Jersey before wintering in tropical and subtropical oceans. It is generally late into spring before we see them appear in Florida on their return trip north. They primarily feed on small fish and aquatic invertebrates, diving gracefully into the water to catch their prey. As I walked along the jetty, there was a constant stream of the Common terns plying the shallow waters adjacent to the rock edifice, many carrying their prized catch.

Common tern at Barnegat Lighthouse Inlet

Forster’s tern

Continuing down the jetty, it became obvious that there were more than the Common terns that were working the shallows. A tern we see throughout the winter and spring in the south is the Forster’s tern. The Common and the Forster’s can be difficult to differentiate in summer. Forster’s terns tend to be slightly larger and more robust than Commons. But honestly, this difference is difficult to tell when the bird is several hundred yards away. One of the more reliable ways to distinguish one from the other is to check the wing coloration. The wings of the Common as seen in the first photo tend to be darker while the Forster’s seen in the second image has a paler “frosted” appearance. In winter, telling the difference is a lot easier as the Common has the full black cap that both sport in summer while the Forster’s in winter has only a partial cap which looks much more like ear patches.

A Forster’s tern emerges from the water after diving in for its prey…..

The final tern of our triad is the Least tern. This little guy was first spotted all the way out at the end of the jetty. Its rapid fluttering flight make it the easiest to distinguish of the three species. As it gets closer, it’s noticeable smaller size and it’s unique “head-light” hood coloration remove all doubt.

Least tern

It’s always remarkable to watch how adept all the terns are at finding and seizing prey below the surface of the water. Scientists estimate that the speed of a tern entering the water in a steep dive may be as high as 35 - 45 miles per hour. Like other ocean dwelling birds of prey, terns use a technique known as “plunge diving” where they hover over the water and then swoop down to catch their prey at or below the surface. The birds tend to hover directly over their prey which minimizes the angle of diffraction or bending of the light a they look through a column of water.

And so, yes…one good tern does deserve another and we were treated to the three most expected terns on our walk along the inlet at Barnegat Lighthouse. We’ll return here during the winter months to find a very different assemblage of birds….those which have come down from their northern breeding territories and have replaced these terns which for the most part have headed south. An ever-changing cast of characters in Nature.

Tech Tip - Today’s tip is primarily for those folks out there who are using the Nikon Z series of cameras. I have found that the best setup of capturing fast moving fly-by birds like these terns today is to go “manual” and set the aperture around f/8 and the shutter speed at no less than 1/1000 sec. An “Auto” setting on the ISO will ensure decent exposures, for most weather conditions. For acquiring and maintaining proper focus, I find that you really need to use Continues Focus with the mode set to Wide Area AF with Subject detection set to Bird. In older versions of the Firmware for the cameras, Animal detection seemed to work about as well as Bird, but the most recent updates make the use of Bird detection the best choice by far. For those of you using different platforms, keep experimenting until you find that perfect setup for “most” situations.

Finally, regardless of the camera body, I find that zoom lenses are the way to go. It’ll pay big dividends in the long run. While older “pre-mirrorless” prime lenses were consistently sharper, the new lenses are for the most part comparable. With my 100-400 lens, I’ll acquire the bird at a wide field of view between 100-200 mm and then zoom in to the higher 300-400 range. Much easier to first acquire and then track a small fast moving subject like these terns. Bottom line is to just get out there and practice shooting with different setups until you find your ‘perfect’ combo.