Hacker News new | ask | show | jobs
by deltaqueue 4630 days ago
My first thought would be to scoff at your criticism. Would the birds' travel patterns be any less impressive if they were resting for very short periods during these 200 days? The sensor measures acceleration, so the only potential confusion might be with light movement near ground / trees.

But according to another study, some migratory birds rest for only seconds at a time during their flights:

http://www.livescience.com/1045-migrating-birds-hundreds-dai...

At 4-minute intervals over 200 days, you have 72,000 datapoints. There are 1,920,000 9-second intervals (avg nap period from other article) over 200 days, so given their data collection spans only 3.75% of this time there's a chance they missed one of these naps.

Nevertheless, this is still very interesting.
3 comments
azernik 4630 days ago
That got me curious, so I ran the numbers on the chances they'd miss all of the naps; assuming these birds take only one 9-second nap a week (28 naps total over 200 days) there's a 35% chance the researchers would have missed all of them ((1 - (28 / 1920000)) ^ 72,000), which is pretty reasonable. But that chance goes down to 8% for one nap every 3 days, and to 0.055% for one nap a day. I'd say maybe one 9-second nap every few days is the lower limit of what I'd find plausible (assuming this was run for only one bird).

EDIT: Ah, missed this in the article - they were three birds. So the chances they'd miss all naps for all three birds goes down to 0.055% for one nap every three days, and 4% for once a week. So 9 seconds once a week is barely believable, but if they can reproduce this with another couple of birds that becomes really unlikely.

link
Gravityloss 4630 days ago
Those thrushes don't land to just nap for 9 seconds and then take off. They sleep for 9 seconds during a longer rest period, because they have to stay alert. They can't fly during the day because of airborne predators.
link
Someone 4630 days ago
"My first thought would be to scoff at your criticism. Would the birds' travel patterns be any less impressive if they were resting for very short periods during these 200 days?"

The criticism isn't aimed at the birds; it is aimed at the logic of the researchers. The critic claims their conclusion does not follow from their data.

link