referring to the spike on the upper mandible. This serves as a sidearm to help dispatch prey.
But for me, having first flicked through guides to the birds of Ireland as a child, it’s always been the eyes: seemingly pure black, as if the pupil has consumed the rest of the surface to soak up every drop of light it can. In this respect, falcons are almost totally unlike any other birds of prey. And even on a moving bird at a distance, they can sometimes be seen clearly. Most often for me they’re encased in the head of the kestrel that haunts the banks of the river near my home, waiting in the wind for rodents to leave their ultraviolet calling cards, the drops of urine that will draw their reckoning to them. The black crown jewels of the kestrel can venture into a colour spectrum beyond that of human sight, and it is this that guides them through the grassy labyrinth.
We have three native falcons in Ireland. The peregrine is the king; at full dive, it’s the fastest animal on Earth, tearing down cliff faces and mountainsides with such velocity that it can decapitate its victim on impact. By far the most familiar is the kestrel. It’s perhaps our commonest raptor (though the sparrowhawk could also stake a claim). The kestrel thrives in the grassy verges that border our main roads. Here it hovers (the only falcon we have that does so) with consummate patience, waiting for its prey to betray its presence before descending in steps, readjusting coordinates for the final pounce.
Then there’s the merlin, the smallest of the three. Rather than relying on patience or a devastating dive, the merlin is a pursuit hunter, winning its meals through agility and perseverance. While the peregrine rains death on its victim from above, the merlin hunts lower to the ground, often forcing its victim skyward. Twisting and turning on frantic wingbeats, it’s as if the bird delights in exhausting and outmanoeuvring its prey. Where possible, the merlin will give itself the edge by ambushing its victim on the ground, sullying it with a standing start. Even when flying about in the open, the rapid, flicking flight style of the merlin evokes that of a thrush, allowing it to disguise itself in plain sight – until it is close enough to give chase.
Birds of prey are famously dimorphic; females are larger than males in a reversal of vertebrate norms. In the falcons this is particularly pronounced. The male is a third smaller than the female, leading to the name ‘tiercel’. Given this, gender roles play a key part in merlin life. The slate-grey tiercel, smaller and swifter than his mate, uses his speed to poach small passerines in flight. The bulkier female, with more punch to her killer blow, can tackle larger songbirds, up to the size of thrushes. Sometimes the pair will even work together to win a meal: one bird flushes the prey, the other takes it out. Between them, they provide a regular protein supply for young merlins each spring, reared in treetop eyries in mountain ranges across Ireland. At first the male does the bulk of the hunting, but once the chicks have matured enough for the female to vacate the nest, she chips in to fuel their rapid growth.
It is in its springtime demesne that the merlin resumes its rivalry with another inhabitant of our mountainsides: the skylark. Every breeding season, this rambunctious songbird can be heard blasting out a winding stream of notes from high in the air, wings beating frantically to keep it aloft.
Skylarks are among the merlin’s favourite prey in Ireland, second only to the meadow pipit. The male skylark’s song, as with that of almost all birds, is used to attract a mate and declare territory. But it also plays a vital role in the species’ relationship with the merlin. The fittest males can sing mid-air with the most vigour – and typically, it is these males who are spared the killing embrace of the merlin.
Silent males, or poor singers, are not so fortunate. Like the merlin, the skylark is an accomplished aerial acrobat. But only males with a powerful singing voice – a vocal expression of their flying prowess – can hope to outpace the merlin in an airborne dogfight. Less accomplished songsters stand a better chance if they simply drop to the floor and stay out of sight. Because of this, the airborne singing of a strong, healthy skylark is akin to the prancing of a svelte antelope on the savannah. It advertises fitness and virility, as alluring to a prospective mate as it is dissuasive to a hungry merlin. A predator’s energies are better spent in pursuit of a slower target. It’s just one way the merlin has helped prune the skylark population to peak fitness, and hone its mating rituals over many generations. Concomitantly, faster skylarks have undoubtedly left slower merlins to starve in their wake over the eons, leading to the refinement of the tenacious pursuit predator that torments their descendants today.
Treetop nesting does not come naturally to merlins in Ireland. Traditionally birds of uplands in spring, for generations merlins nested amongst heather, seeing off any avian interlopers with ruthless aggression. As afforestation has ravaged the uplands, they’ve increasingly taken to nesting in trees, commandeering disused corvid nests for their own ends.
Perversely, merlin chicks born in trees are often more likely to fledge than their counterparts on the ground, perhaps because there are fewer predators to threaten them high in the branches. But this dramatic change in the landscape hasn’t been entirely beneficial for our smallest raptor. The razor-sharp, pointed wings of the merlin are designed for pursuit in open terrain; this is not a bird of confined, wooded spaces, where the broad, rounded wings of the sparrowhawk come into their own. The loss of the heather has shrunk the available habitat in which breeding merlins feel most at home.
The merlin is not as cosmopolitan as our other falcons. Kestrels, predators of farmland and road verges, are easy cohabitants with humans. Among the peregrine’s favourite prey are pigeons – pigeons that thrive like rats in urban spaces. Because of this, peregrines have followed their ambitious human counterparts from the remote hillsides and clifftops to the cities in search of an easier life. They’ve taken to hunting amidst high-rises and quarries, and the crannies atop churches and cathedrals make ideal nesting spots.
In general, the merlin hasn’t transitioned as well to the world of man. The bulk of its small Irish breeding population remains confined to the shrinking pool of suitable upland habitat each spring. This makes it one of our more difficult birds of prey to find, and much cherished amongst birders.
Like its cousin the peregrine, the merlin was also hit hard by pesticide poisoning, building up through the eco-system to impact the predators at the top. In North America, where the merlin–peregrine dynamic also exists, this even led to a curious shift in merlin behaviour. When the peregrine went into decline, the merlin suddenly found itself the top falcon on the winter wetlands of Washington State. With no peregrines to challenge them, the merlins started hunting more in the open with a swagger becoming of an apex predator. However, when peregrine numbers rebounded, the merlins resumed the low-to-the-ground hunting more typical of their species. Perhaps this was to avoid the wrath of the peregrine – they both dined on the same prey, and a peregrine is certainly large enough to make a meal of a merlin.
Wetlands are oases for birdlife in winter. It is here that the merlins typically descend to after their upland bounty has run out and the weather starts to turn (though some males lag behind in the mountains to hold on to their cherished breeding territories). This is when the merlin becomes a menace along our coasts, often perching on logs and other flotsam to catch its breath or enjoy a kill after another frantic chase.
It is in the hopes of seeing one of these wintering hunters that I make my way to Dundalk, County Louth, home to one of the largest areas of exposed mudflats in the country. It’s exactly the kind of place that wintering merlins frequent.
…
The main street is desolate. Pubs, bookies and antique shops are locked up for Sunday. There are no signs of the Saturday night carnage as the road leads onto a bridge crossing the Castletown River. To my left, the vast banks are coated in grass stretching away into the countryside. To the right, the Castletown meanders restlessly towards Dundalk Bay.
The bay is one of Ireland’s largest natural harbours. It is this strategic advantage that has drawn envious invaders to Dundalk over the centuries.
