[rudian]

The surprising part is that we have a battery that lasts that long for tracking “in real time” and doesn’t weigh the bird down. How’s that possible?

The article mentions that is solar-powered, but even then how much power could it generate?

[shellfishgene]

The Icarus trackers weigh 5 grams. https://www.icarus.mpg.de/28874/sensor-animals-tracking See the 'technolgy' sub headings in the menu for more info.

[Reason077]

The tracking device is solar powered so presumably can get away with a very small battery. They mention in the article that it goes offline at times while the bird is resting because it can be covered by feathers which prevent it from getting enough sunlight.

That said, as if it wasn't impressive enough that Godwits can fly over 8000 miles non-stop, it's even more amazing that they can do it while burdened with a tracking device!

[joe__f]

I don't know how much this type of bird weighs, but I imagine 5g for the tracker is a small percentage of its overall weight

[jacquesm]

4 Kg is only about 5% of the weight of an average adult male. Now imagine that weight tied to different places on your body. On your back it might not be a big issue, but glued to the tip of one finger or maybe tied to one of your toes it could effectively disable or immobilize you.

The weight isn't the whole story, it's how it is placed that matters as well.

[nickpeterson]

It’s a matter of weight ratios, how can a 5oz bird carry a 1lb coconut?

[bregma]

It grasps it by the husk.

[kijin]

Distance of 70 feet or 7,000 miles?

[gbil]

from the link

>The transmission technology will continue to be of great importance, as sensors weighing five grams are still too heavy for many animal species: 70 percent of bird species and 65 percent of mammal species, not to mention amphibians or insects, cannot be equipped with sensors using the current technology. The next generation of Icarus sensors will therefore weigh just one gram.

This is just amazing

[onychomys]

And the really bonkers thing about many birds is that the single gram will still be a sizeable fraction of their total body weight. Chickadees and nuthatches (and other birds of that size) weigh somewhere between 10 and 15 grams, usually. Zebra finches are about the same. It'll be a really long time before we can put sensors on those!

[jfk13]

According to https://www.rspb.org.uk/birds-and-wildlife/wildlife-guides/b..., the bar-tailed godwit weighs around 230-450g. So the tracker would add somewhere around 1-2% of its weight.

[kwhitefoot]

Between 200 and 600 g according to https://en.wikipedia.org/wiki/Bar-tailed_godwit#Description

[OJFord]

An African or a European bird?

[F00Fbug]

Not much, but the design of these things is incredible. I spent 20 years managing the operations for the ground processing of this data in North America. We worked closely with the transmitter manufacturers to certify them for use with the system (https://www.argos-system.org).

Microwave Telemetry builds the smallest ones: https://www.microwavetelemetry.com/solar_ptts The design and manufacture of these devices is incredible. The guy behind the company is an incredible engineer (and a nice guy)!

[tda]

> Since landing in New South Wales, 4BBRW’s tracker has intermittently gone offline, which is common as birds rest because their feathers can cover the solar charging panel.

So surprising you can run a GPS on a solar panel of about 1cm2 (my estimate), see picture in article

[foxfluff]

There are solar powered wristwatches with GPS.

[danw1979]

Article mentions a solar panel on the tracker, which seems positioned to receive charge when the bird is on the wing, because when the bird landed it’s feathers covered it up.