Tonight, my great and good friends of the Secret Science Club are presenting a Zoom lecture by naturalist and field researcher Scott Weidensaul, author of A World on the Wing: The Global Odyssey of Migratory Birds.
As a child growing up in Pennsylvania, he became obsessed with the Appalachian Mountains, raptors, and migration. In the 1990s, he traveled throughout North America studying migration patterns, and he recently has traveled the world
North America has lost about a third of its birds in recent decades.
Grassland birds, such as bobolinks and meadowlarks, are particularly hard hit. Waterfowl have rebounded due to efforts to protect and restore wetlands. If we put the same time, effort, and money to restoring grasslands, these birds should rebound as well. Progress is being made to restore migratory bird populations, and our ability to crunch massive amounts of data has revolutionized research. Miniaturized tracking devices also help, some are small enough to place on migratory butterflies. We also have better ideas about bird physiology- some of these birds can spend months on the wing while they migrate.
Not all birds migrate, but the dusky grouse migrates uphill in the Rockies by foot. The semipalmated sandpiper migrates thousands of miles to and from its Canadian breeding grounds. To compare birds to even the most elite human athletes is to shame the birds. The sandpipers gorge on crustaceans called Corophium, stocking up on Omega-3 fatty acids before migratiing. Most birds migrate at night, using celestial navigation. Birds also have magnetic sense, with a form of quantum entanglement (spooky action at a distance), using a visual pigment called cryptochrome, which becomes magnetized, allowing the birds to sense the Earth's magnetic field. Every goose pooping on the golf course has this magnetic sense.
Just about everything humans can do, birds can do better, certain birds, such as bar-headed geese, can fly higher than the 'death zone' for human climbers. Birds have a respiratory system superior to mammals' lungs- their lungs are attached to air sacs accessed through hollow bones. Bar-headed geese have special hemoglobin which allows them to fly at excessive altitudes.
Alpine swifts migrate to Africa for the winter, flying from Switzerland to western Africa without stopping for two hundred days. Common swifts fly continuously for ten months, feeding on the wing on flying insects. Great frigatebirds, being native to the Galapagos, have little fear of humans, and are easy to have transmitters affixed to. The birds are not waterproof, so they fly nonstop to hunt fish- they undergo unihemispheric sleep on the wing, and after feeding their young, sleep on the nest for long periods. Even the migratory birds in our yards, such as warblers, undergo unihemispheric sleep. The birds need food resources at both ends of their migratory route. Certain birds, such as bar-tailed godwits, engage in hyperphagia, overeating, for days before migrating, and their digestive systems atrophy for the trip, and regrow their guts when they arrive. The most important foraging sites for bar-tailed godwits are mudflats on the Yellow Sea, which teem with invertebrate life. The loss of these habitats to the construction of seawalls and aquatic farms are injurious to birds, a twenty-one mile long seawall in South Korea resulted in habitat loss which decreased the red knot population by one-fifth. The spoon- billed sandpiper, which migrates from Eastern Russia to the Chinese coast, is down to a population of about 400.
Conservation efforts are underway on the Yellow Sea coast, with the authoritarian government of China halting all development on the mudflats. Certain sites are now UNESCO sites.
Bird trapping is also a problem, with birds such as the yellow-breasted bunting, once among the most abundant songbirds, experiencing catastrophic population decline. If they go extinct, this would be the equivalent to the extinction of the passenger pigeon. Bird trapping in the Mediterranean is rampant, with about eleven million migratory songbirds being killed in Egypt, France (where the ortolan bunting is a prized dish), and Italy. The 'black hole' of bird loss is Cyprus, where up to three million birds are trapped, usually using birdlime, a sticky substance smeared on twigs, which can trap birds. In Cyprus, the birds are plucked and fried in an illegal dish called ambelopoulia. Much of the poaching has occurred on British military bases, with local police, at considerable risk, using drones to catch poachers, and British conservationists send anti-poaching specialists. Scott Weidensaul had to wear a bulletproof vest while observing these personnel.
Climate change is the biggest problem facing birds, changing distribution patterns. He doesn't care if you believe in climate change, the birds do. Many species of birds have changed their migration schedules due to warming. Some birds, such as fox sparrows and eastern phoebes, have show flexibility in migration, but most of these are short or mid-distance migrants. Long-distance, such as black-throated green warblers, are adversely effected by climate change. Certain birds, such as pied flycatchers, time their migration to exploit the emergence of caterpillars, but the caterpillars emerge earlier now. North American birds, not having to cross a desert and a sea, are less affected.
Climate change doesn't cause uniform warming- in portions of the Canadian Arctic, falls and winters are colder, but summers are much hotter, so insects emerge earlier so chicks can starve. The Audobon Society modeled bird habitats and determined that scarlet tanagers will lose about ninety percent of their oak-and-beech forests by 2080, and the habitats won't be able to shift to keep up with warming.
Advances in computing power can help in bird conservation. Doppler radar stations can be used to monitor bird migration, even allowing determination of bird size, direction of travel, and the calculation of bird numbers per cubic meter. Shifts in migration can be shown. Radar data allowed researchers to determine that 2.9 billion birds have been lost. Radar cannot determine taxonomy, so birders on the ground, using the E-bird system, can verify what species of birds are migrating. Using this data, optimal habitats, such as pop-up wetlands on farmland, can be created- payment to farmers would be cheaper than buying land outright. City lights can confuse birds that navigate by starlight, drawing them to cities. Automated alerts to building owners can inform them to dim lights as large flocks of migrating birds approach. Urban bird habitats in city parks can also be more effective than buying undeveloped land. GPS units that transmit data cellularly can track birds, with Project SNOWstorm being an effort to track snowy owls.
Small songbirds and migratory insects and bats can be tracked with the Motus system, and numerous local projects are expanding the receiver station network.
This is an amazing time, and a terrifying time, for migration. It's easy to despair, but there is hope that the challenges of migratory birds can be met. Scott Weidensaul cited the Amur falcon migration from Siberia and Eastern China to Southern Africa. Nagaland, in eastern India, is a state characterized by conflict between a local Burmese ethnic population espousing a Baptist Christian religion, it was discovered that falcons that typically gorge on breeding termites before migrating were being trapped by farmers whose fields had been flooded by the construction of a dam. The starving farmers literally believed that the falcons were manna from heaven. There was an outcry among the international press, leading to an effort by conservationists and the hungry Naga to stop the hunt overnight, with former poachers guarding nesting sites, and efforts to jumpstart a tourism industry, which is difficult to put into place due to Nagaland's remoteness and an anti-India insurgency. Mr Weidensaul painted a picture of bad roads, bandits, and Baptist headhunters. Tourists are arriving, but the tourist economy is not as egalitarian as the falcon trapping economy. Trappers-become-tour guides don't have equal access to prime roosting grounds or the ability to install western style facilities for tourists. Roads bring development, logging, and hunting- they are the worst threats to birds... but they would be a boon for Nagaland ecotourism and conservation. Strides have been made, but how sustainable are they?
Every bird that makes that leap into migration is ordinary, and extraordinary. They have evolved amazing systems to navigate the migration process, but it's not enough now, the birds need our help.
The lecture was followed by a Q&A session. The first involved the evolution of migration patterns. Scott believes that this is an incremental process, migration is genetically coded, and some birds are born with 'bad software', with some taking riskier routes, such as oceanic routes, but success among a few would be selected for. During the Ice Age, sea levels were lower, so now overseas routes would have been overland on a geological time scale.
Another question involved the use of birds as climate change 'surveyors'. Cornell's eBird program has gathered data, and almost no migration routes have been unchanged by temperature change and shifting wind patterns. The difficulty for birds is that they tend to depend on stable weather patterns, which are being perturbed.
Another question involved the banning of DDT, which decimated raptor and common loon populations. Bald eagle populations have quadrupled over the past couple of decades, which does have a ripple effect on other bird populations, such as tern populations.
How do magnetic pole shifts affect birds? Birds' magnetic senses aren't cued to polarity. There might be some confusion, but birds don't function as compasses, and should be able to handle things well.
How do scientists band birds? Banding is the most effective and least effective method of tracking birds. Marking birds as individuals is crucial for determining migration, longevity, and mating practices. Most birds return to nesting spots and overwintering spots. If you find a dead bird, check for a band- the return on banding is pretty slim, only a fraction of the bands are recovered. GPS locators are more effective. Birds can be netted using audio lures and the geolocators can be evaluated. One great thrush in Denali park has been tracked to the upper Orinoco over seven migration seasons. Other thrushes living in proximity in Denali shared a similar proximity in southern Argentina.
How did the COVID-19 pandemic effect bird migration? Differences in observed migration was probably more due to increased observation rather than decreased activity. People suddenly started noticing nature, started observing birds.
There are migratory birds, semi-migratory birds, irruptive birds that migrate due to changing food availability.
Another question involved Ducks Unlimited- whatever your opinion of duck hunting is, duck hunters have raised a lot of money to preserved wetlands. There is enlightened self interest involved, but the effectiveness cannot be denied. The single largest anthropogenic factor in bird deaths is the domesticated cat- keep the cats inside, they kill billions of birds each year. Trap, neuter, and release programs maintain large predator colonies- keep your cats inside.
Some Bastard in the audience (and another person in the chat), asked how even apartment dwellers can help birds. Plant native plants, especially ones with fruits with a lipid content. Choose your coffee well, pay more for certified shade-grown, bird-friendly coffee sown in forest habitats, subsidize small farmers who grow their coffee bushes under native forest canopy. Look for the Smithsonian label. Certain co-ops are engaged in reforestation efforts, improving bird habitats.
Migratory birds can carry pathogens, such as avian influenzas, which are carried by waterfowl such as gulls. Birds can also be used as sentinels for pathogens, such as West Nile virus, which decimated many wild bird populations.
Another city dweller asked for resources about city-living birds. Migratory songbirds don't typically migrate in large flocks, but they make calls to avoid collisions. Rooftop antennae, available for about twenty dollars, could pick up migration calls to give a more granular picture of birds in transit, giving a detailed picture of the night sky.
The lecture was fantastic, accompanied by wonderful pictures. It was sobering, but Mr Weidensaul challenged us, and gave us hope. Kudos to this Pulitzer prize finalist, and Margaret and Dorian. For a taste of this lecture, here is a lecture by Mr Weidensaul from last Fall: