When it comes to locating prime stretches of fertile water in the expansive open ocean, fishermen have many tools at their disposal. However, nothing signals great things to come quite like pelagic seabirds feverishly working the surface. Frigates, terns, gulls, petrels, gannets and shearwaters are only a few of the bird species anglers encounter while plying offshore waters, and by identifying, observing and analyzing specific activity in the sky helmsmen can make accurate estimates of what’s likely occurring beneath the surface.
With nearly 70 percent of the Earth’s surface covered in saltwater, and our sea levels rising every year, anglers have a lot of water to explore. Some stretches teem with life, while others are lifeless dead zones low in oxygen content. Thankfully, the prized game fish we go to great lengths to pursue are all attracted to a few key features including underwater structure, surface floating debris, current breaks, color changes and the presence of baitfish—all of which can be pointed out by our feathered friends high in the sky.
Pelagic seabirds spend a majority of their lives covering open stretches of water and are highly adapted to survive amid the harsh and barren marine environment. What enables these incredible creatures to cover miles of open water and glide for days is a natural evolution resulting in hollow bones. However, as one would think it’s not to shed weight, because the hollow bones are extra dense to increase strength. The unique bone structures actually house air sacs that allow for greater absorption of oxygen while both inhaling and exhaling to assist in such demanding aerobics. Adding to their impressiveness, some seabirds are also specially adapted to drink saltwater and excrete the salt from a highly adapted cephalic gland.
The first step to getting fully acquainted with our surroundings is being able to identify the most commonly encountered high flyers and getting to know a little bit more about each. Though frigates, terns, gulls and petrels feature very diverse hunting techniques and physiological features, all seabirds feed almost exclusively on fish, squid and crustaceans. No matter how they have evolved to accomplish this feat, birds are the world’s best fishermen and provide observant anglers with a wealth of valuable knowledge.
Starting with arguably the most prized sight offshore, the magnificent frigatebird is easily distinguished by its large wingspan, forked tail and menacing black silhouette. What’s special about frigatebirds is that they are perfectly designed to cover huge distances of open ocean with a giant wingspan that’s proportionately larger than any other bird’s wing to body mass ratio. Yet their thick plumage doesn’t provide the same waterproof coating that’s common to other seabirds. They forage exclusively on seafood, but cannot get their giant wings wet. Because of this unfortunate characteristic, frigates are forced to scavenge or delicately snatch baitfish off the surface with their elongated beaks. With knowledge of the frigatebird’s unique hunting strategies, anglers have concluded that frigates typically follow predators, not baitfish. Frigates stand little chance capturing forage fish that rarely come within reach of the surface without predator interaction, so they simply follow large pelagic game fish and wait for them to corral baitfish to the top. While a frigate off the coast of Miami is always worth investigating, across distant fisheries where they are more common sights anglers have a preference for finding mature frigates that have black heads, compared to juveniles with white heads that might still be perfecting their fish finding skills.
There are nearly 40 species of terns worldwide within the family Laridae, though in our region sooty terns are some of the most numerous and easily identified by their black face and back with white underside. Royal terns are also common offshore and distinguishable by their yellow beaks. In the Florida Keys, terns are commonly encountered offshore shadowing fast-moving schools of blackfin and skipjack tuna. Terns have great vision and can even be spotted sitting on the surface peering into the deep blue. And although they are often called tuna terns, these small statured seabirds more commonly follow individual baitfish, unlike frigates that are more typically encountered shadowing predators.
While extended visibility afforded by a heighted vantage point is beneficial to any pelagic hunter, gannets and terns are equipped with ultraviolet sensitive receptors that provide a natural polarization enhancing visual acuity during low light conditions. Even more impressive, certain species of seabirds have powerful olfactory organs enabling them to key in on oily baitfish. Studies on shearwaters and petrels, which are classified within a group of tube-nosed birds, have determined they can sniff out a potential meal from upwards of 30 kilometers away!
Now that you know what to look for, by observing the movement of specific birds you can also have a better understanding of what lies beneath. While seabirds are after the same thing and all have similar characteristics, they behave with slight variations in different venues, so as with most aspects of sport fishing local knowledge is priceless. By spending time on the water and observing bird activity in relation to what you experience, you will undoubtedly become a more knowledgeable and successful angler.
In the Florida Keys, seasoned captains can accurately determine the size of dolphin by bird behavior and their direction of travel. Royal terns and gulls working the surface in a northerly movement generally mean schoolies are likely feeding below. With birds working to the south, against the flow of the Gulf Stream, captains know gaffers are on the move since they are more capable of stemming the current. Big pairs typically have fewer birds following them compared to an aggressive pack of peanuts, because two mature fish cannot corral bait on the surface as effectively as a gathering of flippers.
Similarly, anglers in The Bahamas fishing for tuna around the famed Corner know that frigate birds spotted on the radar heading north are likely following yellowfin tuna, while birds steaming south are often focused on skipjacks. Though not as common in Florida as they are in Bermuda or the Dominican Republic, the longtail tern is unique in its preference of forage, favoring flying fish and more importantly flying squid. Because of this propensity to shadow flying squid, a blue marlin’s favorite bait, many captains hold this majestic seabird to the highest standards knowing that when a longtail is in the spread there is a great chance billfish are feeding in the near vicinity.
Though every helm station should be outfitted with a quality pair of binoculars, modern radar can pinpoint a single bird from miles away. While a radome will work for close target acquisition and the newest solid-state pulse compression units are impressively outfitted, for even greater range and target resolution you’ll want an open array radar with Doppler effect. Regardless of chosen unit, when dialing in your settings start by adjusting the gain until you see clutter on the screen. If the gain is too high it will be hard to spot birds, while too low of a gain setting won’t return the smallest targets. Once set up, a light fuzz will cover your radar and birds will appear as small returns with a different density. The latest radar units equipped with Doppler can even display different colored returns based on the target’s direction of travel.
While technology has helped improve our interactions with trophy game fish, bird activity is perhaps the greatest indicator. Carefully study the skies and with practice you’ll be able to determine which bird schools will lead the way to impressive catches, and which will get you nowhere.