One of many stopping in China around Yellow Sea— red knots, great knots, godwits, other sandpipers
Shorebirds have a greater task than seabirds: can’t land on ocean or feed during journey
Degradation of their feeding grounds— mud flats around the coast → failures in migration
Chinese gov’t taking some measures to preserve these grounds, banning development
Miniaturization of geolocator, etc. making tracking and quantifying migration patterns more effective
2. Quantum Leap
Godwits → longest nonstop migration known; go through cycles of organ compression and regrowth
Many variations on the “binge-bulk-shrink” theme among other migratory birds
Metabolisms are finely tuned for their long journeys- maintain water homeostasis, different efficiencies of breaking down fat, muscle, etc.
Omega-3 = important fuel
More efficient respiration set up to manage in hypoxic air conditions
Attached mini EEG sensors to frigatebirds to monitor sleep!
Don’t sleep much- hemispheric sleep, micronaps… but somehow manage
Some birds have growth in certain brain areas (eg. hippocampus) when needed, then recedes when unnecessary to balance metabolic needs
Magnetoreception = one of many ways birds navigate (also by stars, genetics, volatile chemicals)
Works by radical pairs of electrons, cryptochrome receptor Cry1a, and quantum entanglement
3. We Used to Think
Advances in tracking technology, automation → VHF radiotelemetry is getting affordable and effective to track migratory birds
Motus network— towers set up for any specific project pick up signals from all tags
Gives us data on bird’s lives previously hidden, clues to where their biggest threats are
Shifting assumptions on whether old-growth forests are really essential/the best for birds— youngsters thrive in the dense, difficult-to-navigate, photosynthesis-rich new-growth edge areas
So-called “old-growth” forest really what grew back from clearcut logging centuries ago → no structure like truly old forests; margins provide those structural advantages
Can design logging patterns that are actually beneficial to birds, creating diversity of forest conditions
Migratory connectivity: diff populations of same species ma take different paths, go to sites somewhat separated from each other (or vice versa, which is actually what migratory connectivity is) → implications for conservation
4. Big Data, Big Trouble
Doppler system can pick up “bioscatter,” whether it’s birds or bats or insects → now getting more specific at identifying how far apart birds are flying, etc.
Unfortunately, taxonomically agnostic → can’t tell whether constant/increasing migration numbers are from threatened species or not
eBird: collection of tons of data from birders who had records that were going to waste; gamification helped it really take off
Identified trends → better use of land for farmers (ex. flooding certain land in off-season of agriculture)
Big data → see effects of light pollution on impacting migration patterns — could also be a way to solve it, but not implemented at the moment.
Also just less birds now than ever before— grassland birds like sparrows, etc. most threatened
5. Hangover
Carry-over effects: conditions in tropical lands thousands of miles away, many months earlier may predestine a bird as it flies north back to its summer grounds— better health, reproduction, etc. (not unique to birds)
Some exceptions to this— ex. godwits can compensate for bad luck or challenging conditions on migration (stable, predictable food at stopover points)
How does a bird’s microbiome change between its two habitats?
How much of bird mortality is because of things that actually happen during migration (when most deaths occur) vs how good of a winter one had?
6. Tearing up the Calendar
Climate change = affecting timing of seasons, temperature extremes, sea level (and thus tidal habitats)
Can’t just shift habitats bc require certain kinds of forests that don’t grow overnight
Changes winds, which are critical for migratory birds
Phenotypic plasticity = ability for organism to adapt to different environments (not by change in genetics)— can be hard do distinguish between evolution, sometimes
General response to climate change = smaller body size (across most animals!), longer wing length (maybe to accommodate longer migrations that are necessary)
Hummingbirds changing migration patterns— staying in frigid weather longer! Other species also changing timing of migration → temporal isolation from other populations that can lead to speciation.
7. Aguiluchos Redux
Aguilochos = hawks— refers to Swainson’s hawks, which were being decimated in their wintering grounds in Argentina due to noxious pesticides used to kill grasshoppers
New efforts to colorband not just adult hawks but all chicks → created recognizable population, traceable families, etc. for the first time
Found that Swainson’s hawks = very slow to adapt to new habitat/opportunities, even as old ones may be degrading
Hawks dependent on agriculture: alfalfa farms → tons of squirrels → prey for hawks (and farmers like that they are killing the squirrels that are eating their alfalfa)