<
https://www.theguardian.com/environment/2023/oct/08/grizzly-bears-eat-moths-wyoming>
"The barren mountain slopes of north-west Wyoming might seem like inhospitable
territory for a hungry grizzly bear. Big game animals are few and far between,
and blueberries don’t grow from these rocky hillsides, high above the treeline.
But for a couple of months each summer, this stark landscape becomes a
high-calorie buffet for hundreds of grizzly bears in the Rocky Mountain west.
And it’s all thanks to a small, unassuming insect whose relationship with the
grizzly is as essential as it is unexpected.
The army cutworm moth is relatively large, measuring half the size of a thumb,
and appears drab from afar. But look a little closer, and a dizzying array of
tan and brown geometric designs cover its furry wings. The moths migrate to
these mountain peaks by the hundreds of millions each summer, some traveling
more than 1,000 miles from as far away as Canada’s Northwest Territories.
Full of fat – some biologists call them “bear butter” – they’ve proved to be an
important source of food for the region’s grizzlies.
Biologists estimate about 200 bears each year feast on moths in the eastern
portion of the carnivores’ range. Each gram of moth offers bears about eight
calories, which means some bears will eat up to 40,000 a day.
“A bear could, in about a month’s time, get one-third of the calories they need
to build up fat for hibernation at these moth sites,” says Frank van Manen,
leader of the interagency grizzly bear study team with the US Geological
Survey.
I witnessed this phenomenon one sunny, late-July day about a decade ago while
perched on a grassy, wildflower-filled meadow deep in the Absaroka Mountains. A
bear biologist, a retired science teacher and I peered through spotting scopes
at a mother grizzly bear chucking rocks between her legs into a ravine below.
Her two cubs played next to her, stopping periodically as she grabbed another
granite rock from the steep slope, turned it over and munched on what were
probably dozens of cutworm moths scurrying underneath.
It may seem like an odd pairing. Grizzly bears are a charismatic carnivore
memorialized on state flags and coffee mugs; moths are considered annoying at
best, and pests at worst.
But at a time when other food sources, such as whitebark pine nuts and
cutthroat trout, have been hit by global heating, disease and invasive species,
the army cutworm moth population has remained remarkably stable, making it a
critical ingredient in the grizzly bears’ continued recovery in the US.
Now, scientists are on a quest to better understand the moths – their life
cycle, their migratory routes and their health – since their fate could be
intertwined with that of their much larger predators."
Cheers,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
