If we could see UV would we be hungry or even more repulsed? In the type of coincidence that happens all the time in real life, but is so unbelievable in a blog, Sandra Tsing-Loh talked about vole pee recently during her science podcast from Caltech. Here's the transcript:
Ever wonder how high-flying hunters like hawks spot their meals from so high in the sky? The mystery of Eagle Eyes has been solved, and it's....DIRTY.
At least for the common kestrel.
The kestrel's favorite food is the vole, a beak-watering cupcake-sized furball. They're like the Morton Salt girl. . . They leave a trail everywhere they go, to mark their territory.
A trail... of PEE.
Davide Csermely, from the University of Parma, Italy suspected the pee trail might come in handy to the hungry kestrel. See, piddle just happens to reflect ultraviolet light, and birds just happen to see UV.
To find out if kestrels see vole pee, Csermely released about 100 into an outdoor aviary with four different habitats: voles had tinkled in two; the others were sprinkled with water. Each was covered with a filter that either blocked UV or let it through.
The birds scanned pee-stained habitats the most, and focused on the one where UV was allowed to shine through.
Surprisingly, juveniles who'd never hunted were just as discerning as adults. Proves the birds are born with an eye for prey piddle.
Kestrel parents don't teach their young how or what to hunt, so being hardwired to tell vole urine from any old wet spot is critical...
And clever. As we like to say about kestrels: When it comes to vole pee, they're real whizzes.