New Scientist – June 10 2017

Blue-sky thinking
By dividing the aerial habitat into three zones, aeroconservationists want
to change the way we think about this neglected ecosystem and protect
the organisms that live within it from human incursions
Altitude (km)
13
12
11
10
9
8
7
6
5
4
3
2
1
0
-56°C
Temperatures are average tropospheric
temperatures at mid-latitudes
-35°C
5°C
BASOAERIAL HABITAT
15°C
TROPOSPH
EPIAERIAL HABITAT
MESOAERIAL HABITAT
Noctule bat
Moving vehicle
Cruise ship
Electrical power lines
Wind turbines
Amazon drones
Eastern amberwing dragonly
Red bat
Diamondback moth
Empire state building
Black-sided pygmy grasshopper
Burj Khalifa
Erigeron seed
Ascending/descending aircraft
Hoary bat
Mexican free-tailed bat
Migrating passerines
Bald eagle
Bewick’s swan
Desmoiselle crane
Bar-headed goose
Cruising aircraft
Viable bacteria
Light pollution
SOURCE: doi.org/b7xn
National University of Comahue in Argentina.
Tools such as accelerometers and GPS are
changing that. Progress is being made in
charting the behaviour of larger animals,
including bats, and Lambertucci is using the
technology to study several raptor species,
Andean condors among them.
Until we know more, it is hard to judge the
effects of our airspace incursions. But we can
look at how animals in other ecosystems
are affected by our activities and apply
these lessons to the sky. On land, habitat
fragmentation has detrimental impacts on
living things, for example. In aerial habitats,
this could take the shape of animals making
long detours to avoid tall buildings and cities,
or being lured into spending time circling
light sources while travelling at night. “What
are the costs of that movement to migration
duration, energetic reserves and fitness once
they get to their breeding sites?” asks Ford.
Seeing the light
Light pollution, in particular, could have a big
impact in all three aerial zones. “You can see
light from outside of our atmosphere,” says
Travis Longcore at the University of Southern
California, who researches the impact of
artificial light on biodiversity. Many studies
have reported effects such as seabird chicks
becoming disoriented by overhead lights on
their first flight out to sea and crashing. Future
research aims to find out the thresholds at
which artificial light levels begin to affect the
navigation, dispersal, communication and
reproduction of different species, get a handle
on the size of those effects and determine
the size of dark refuges needed to maintain
natural ecosystem processes.
Computer modelling is helping to quantify
the whole-population effects of both artificial
light spilling skyward and, more generally,
our structural cluttering of the air. Projections
for hoary bats, the species most frequently
killed by wind turbines in North America, for
example, suggest lethal collisions with blades
could spell serious trouble for population
numbers over the next century, seeing
them decline by as much as 90 per cent.
Given the ubiquity of our aerial incursions,
why hasn’t the idea of protecting aerial
habitats come to our attention earlier?
“We are terrestrial creatures,” says Diehl.
“In our evolutionary history, we’ve lived
off the land and, to some extent, out of the
water.” He suspects that our notions of habitat
are deeply ingrained and, like our science,
oriented towards the landscape. We may need
40 | NewScientist | 10 June 2017