Skip to content

Nature

On wind and a thermal, soaring habits of the Golden Eagle (Aquila chrysaetos)

by Dave Armstrong 16 May 2012
On wind and a thermal, soaring habits of the Golden Eagle (Aquila chrysaetos)

The golden eagle is able to traverse the Appalachians using winds and thermals, speeding as it descends and slowing as it climbs, thereby saving energy - Golden eagle via Shutterstock

To a migrant raptor like the golden eagle, Aquila chrysaetos, energy conservation is as important as it is to us. If eagles are too tired after arrival, then egg-laying or food gathering is going to be limited, if not cancelled. To minimise energy use during travel it is necessary to use winds, thermals and behavioural strategies for least exertion.

There is a spring migration though the Appalachian Mountains that can test these strategies in the animal. Ten eagles were fitted with GPS-GSM units weighing 95g (against the 3370g to 5120g of the birds). Data was collected at 30 to 60 second intervals, except when there was no movement, in which case the GPS switched to a 15 minute-interval collection mode.

The birds took just over 5 days to cover the 333km area of the experiment providing on average 51 data points per hour. Thermal soaring and response to winds were successfully recorded on a very fine scale.

By the end of a year's experimentation, it was established that the birds had a stereotype of reacting to high wind speed by changing from thermal to orographic (based on mountain relief) flight. They used available lift at all times but the high resolution data available only from GPS telemetry indicated several undiscovered facts.

soaring eagles

Soaring birds via Shutterstock

Their flight patterns, for example remained constant throughout the year, unlike some observations that infer otherwise. They also surprised Michael J. Lanzone et al by increasing speed on descents and ascending more slowly than expected. The group of raptor scientists, mainly based in West Virginia, and Pennsylvania in the US and Quebec in Canada publish their research paper today in the Royal Society journal Biology Letters.

As increased wind speed causes golden eagles to decrease their vertical air space, it could be argued that industrial scale wind farms on ridges are a great danger to migrating raptors as they descend. However the standardisation of their behaviour does make it easier to predict when and where they are flying.

Eagle safe avenues or operational mitigation at wind farms are perhaps "flights of fancy," But it seems likely that something of this order could be feasible and implemented without any great cost to industry or to the eagles. It's a test of society whether we can manage such implementation and integrate with our local ecologies. The alternative would be standing alone on a barren earth.


Trending Eco-Friendly Clothing

Love My Planet Women's Relaxed Fit Hoodie
Earth
Quick Add
Close
Notify me
Notify me
Love My Planet Women's Relaxed Fit Hoodie
Love My Planet women's eco-friendly relaxed fit hoodieSize Guide Centimeters 8 10 12 14 16 18 Bust 84 88 92 97 103 108 Waist 66 70 75 80 85 91 Hips 91 95 99 104 109 116 Bust: Measure around the fullest part of...
£38.00
£38.00
Close
Notify me
Notify me
Penguins Hate Push-Ups Men's Pullover Hoodie
Earth
Quick Add
Close
Notify me
Notify me
Penguins Hate Push-Ups Men's Pullover Hoodie
Penguins Hate Push-Ups men's eco-friendly pullover HoodieSize Guide Centimeters XS S M L XL XXL Height 171 175 179 183 189 195 Chest 86 93 99 104 116 129 Waist 71 76 81 89 99 112 Chest: Measure all round your chest just below...
£38.00
£38.00
Close
Notify me
Notify me
Lightning Bolt Kids Long Sleeve T-Shirt
Earth
Quick Add
Close
Notify me
Notify me
Notify me
Lightning Bolt Kids Long Sleeve T-Shirt
Lightning Bolt kids eco-friendly long sleeve t-shirtSize Guide Centimeters 3-4yrs 5-6yrs 7-8yrs 9-10yrs 11-12yrs Height 98 112 125 136 147 Chest 60 66 70 75 84 Chest: Measure all around your chest just below your armpits. Height: Your natural height If you fall between...
£18.00
£18.00
Close
Notify me
Notify me
Notify me
Union Jack Tote Bag
Earth
Quick Add
Close
Notify me
Notify me
Union Jack Tote Bag
Union Jack eco-friendly colour tote bagProduct Specification Organic Cotton Tote Bag. Twill Weave (170gsm). 37 x 42 cm (7cm gusset.) Made in India / Designed on the Isle of Wight. Wash Cool, Hang Dry.
£16.00
£16.00
Close
Notify me
Notify me
Prev Post
Next Post

Eco-Friendly Shop

Women's Clothing

Eco-Friendly Clothing for Women Our online shop offers a wide range of sustainable women’s clothing products, including t-shirts, hoodies, vests, sweaters, shorts, and...
Shop Now

Men's Clothing

Eco-Friendly Clothing for Men Our online shop offers a wide range of sustainable men’s clothing products, including t-shirts, hoodies, vests, sweaters, shorts, and...
Shop Now

Kids Clothing

Eco-Friendly Clothes for Kids Our online shop offers a wide range of sustainable kids clothing products, including t-shirts, hoodies and jumpers. Our garments...
Shop Now
Someone recently bought a
[time] ago, from [location]

Thanks for subscribing!

This email has been registered!

Shop the look

Choose Options

Earth Times
Sign up for exclusive updates, new arrivals & insider only discounts

Recently Viewed

Edit Option
Back In Stock Notification
this is just a warning
Login
Shopping Cart
0 items

Before you leave...

Take 20% off your first order

20% off

Enter the code below at checkout to get 20% off your first order

CODESALE20

Continue Shopping