Daybreak on West Sands is greeted by a cacophony of high-pitched whistling calls as loose flocks of wading birds begin their day. These flocks consist of a motley assemblage of various species including ruddy turnstones, curlews, and oystercatchers with their bright orange bills – probing in the damp sandy flats for worms and other small tidal creatures to feast upon, as they have done all winter. This time of year, however, the keen observer will notice a diversification in this avian crowd. Birds not seen since last autumn, such as the eiders that cruise around the tide pools along the coast, begin appearing as the days lengthen and the weather grows slowly but steadily more pleasant.
St Andrews in springtime, like much of coastal Scotland, is transformed into a veritable highway bird migration, as birds from near and far land on the beaches or in the nearby Eden Estuary. For some, St Andrews is their final stop after a long journey from their equatorial winter haunts; for others, St Andrews is merely a pit stop on a much longer journey north to the Arctic circle and beyond.
Often it is the smallest birds that have made the greatest journeys. Along the Kinnessburn, yellow wagtails, diminutive birds named for their tendency to flick their tails up and down as they hop about, are starting to appear as they finish a several-thousand-kilometre journey from the western edge of the Sahara. They are joined by others returning from Africa too: the swallows and martins that now flit through the cathedral’s spires have come from as far as South Africa, crossing savannah, rainforest, and desert to get here.
Not all of our birds are so exotic; many of the shorebirds that flock to our beaches during winter have made the journey of only a few dozen kilometres from inland. Here they wait out the winter on frigid beaches but nonetheless provide plenty of sustenance. Among these short-distance travellers are the curlews, long-billed birds that during summer, will travel inland to breed. Other birds eschew the land altogether and spend their winters in the sea. On the coastal cliff s that stretch from the aquarium to the pier, hundreds of fulmars — tube-nosed seabirds whose lifespans can exceed 50 years — can be observed in pairs, nestled on narrow ledges after having spent the winter fishing out of sight of land.
Some of our familiar Scottish seabirds take part in the longest migration of all. Arctic terns, many of which nest on the Isle of May off the coast of Fife, and which can occasionally be spotted in St Andrews, are record-holding long-distance migrants: each year, these rabbit-sized birds undertake the longest migration of any bird, flying to Antarctic in the autumn and returning to the coastlines of the northern hemisphere during the spring, a round trip journey of up to 90,000 kilometres. During its thirty-year span of the average Arctic tern, the bird may fly almost 2.5 million — the equivalent of flying to the moon and back three times. Crossing continents and oceans in a little over a month — taking detours to fish along the way — these birds are the ultimate migrants.
Approaching this level of cosmopolitanism is the red-necked phalarope, a shorebird whose range in the UK is restricted to the Shetland Islands. Unlike other long-distance migrants, these birds do not head directly south for the winter. Instead of journeying to Africa or the Middle East like other similar birds, the phalarope instead heads west, flying across the Atlantic to North America before heading south to the Caribbean. But this intrepid traveller does not stop here. Instead, the bird turns its beak towards South America, crossing over into Colombia and following the lush, rainforest-covered Andes mountains south, all the way to the Pacific Ocean off the Peruvian coast.
Why does the bird make this preposterously long voyage of more than 25,000 kilometres when it could reach similarly warm equatorial waters off the African coast by flying a fraction of that distance? The most likely answer to this question is that this particular population of red-necked phalaropes are not originally Scottish. At some point in the past — perhaps thousands of years ago — these birds colonised Scotland from North America. But although they spread east across the Atlantic, the birds kept returning to their same wintering grounds off the western South American coast — for no better reason than that is what they have always done. Just across the North Sea, the Scandinavian population makes the much shorter journey to the Arabian Sea.
How can some birds make these epic voyages and return to the exact place each year without fail? Birds have evolved an amazing array of navigational strategies that allow them to accomplish this feat. Like all great human navigators, migratory birds use a compass. But unlike the navigational equipment of human explorers, the birds’ compasses are internal. They can use the sun to orient themselves during the day and the stars, particularly the North Star, to navigate at night. There is even evidence that at least some migratory birds — the humble robin, for one — have the ability to not only sense, but also see the earth’s magnetic field and use it as a guide, thanks to a unique collection of molecules in their right eye that are sensitive to magnetism.
But as the case of the red-necked phalarope demonstrates, migrating birds do not always simply face to the south and keep flying until it gets warmer. Instead, many birds follow specific routes which seem to be defined by landmarks. The birds will follow the path of a river, the run of a mountain range, even highways and other man-made structures, using these as landmarks to guide themselves to specific locations. It seems that the birds use their internal compasses as guides to help them find the general direction in which to fly, and then use landmarks and personal experience to direct themselves to specific locales. But rivers change course, and most roads are no more than a couple of centuries old; so the birds must have some degree of flexibility in the exact routes they take, a testament to their adaptability in an ever-changing world.
But migration has its risks. Although mortality is particularly high for young birds, migration is no joke for any bird, no matt er how experienced. Migrating birds face enormous dangers, from hungry predators to starvation or exhaustion. And in today’s human-dominated world, it has never been more dangerous to be a migrating bird. As many birds migrate during the night, light pollution can result in serious trouble. The bright lights of cities cause tired birds to become confused and disoriented as the usual cues they use to guide themselves become obscured by bright lights. Window strikes from these situations kill millions of birds every year. Migrating birds that winter on the Mediterranean, or simply stop there to fuel up before crossing the Sahara, face the added threat of poachers, who set up glue traps to catch small songbirds as an illicit but unfortunately common delicacy.
Habitat loss is another danger that migrating birds face. Many birds that summer in Europe spend their winters just south of the Sahara. As desertification rapidly expands that desert and unsustainable agricultural practices destroy valuable bird habitat, birds might come to their wintering grounds and find them uninhabitable.
Climate change poses another threat to migrating birds. Migrants often use the lengthening of daylight as a cue of when to head north during the spring. In the past, this ensured that the birds arrived just in time for the spring growing season, and they could feed and prepare to breed and nest. However, as climate change continues to cause unpredictable swings in local climates, many birds are arriving too early, and subsequently starving, or too late, in which case they miss out on the valuable first weeks of the breeding season. Although birds have been adapting to climatic changes for millennia, the rate at which the climate is currently changing is unprecedented in recent history, and it remains to be seen just how well, if at all, the birds will adapt.
St Andrews is a cosmopolitan town. Students from across the world come here to study, some crossing oceans and continents to get here. Likewise, many of the birds we see have made similarly lengthy journeys. The birds that migrate to and from St Andrews are not just Scottish, or British birds. They are truly global travellers