Kestrel hunts in darkness? (1 Viewer)

[Rustywater]

I was driving slowly along a farm track in the Cambridgeshire fens this morning at 6.45am. It was quite foggy and still dark. (Even darker than usual due to the fog). I saw what I first thought was a young rabbit in the middle of the track as that is very common. As I got closer I realised it was a kestrel standing on something dark it had caught that I couldn't make out in the foggy light of my headlights. It obviously didn't want to let go of what it had and didn't move. I stopped and reversed a little to see if I could go round it although there was not a lot of room. It then took off with it's prey and flew slowly and heavily into the fog. I drove slowly on and a few yards into the fog it had settled again with enough room for me to pass.
I still couldn't make out what it had caught but was surprised to see a kestrel with prey in the dark. I was under the impression they only hunted in daylight.
Would anyone know if is this unusual behaviour or just an early starter?

 

[Nutcracker]

Interesting one! Presumably being a farm track, no street lights to assist it either. Any nearby that it could have hunted under, to then come to the track after catching its prey by streetlight?

Guess the simple answer is, no-one knows what Kestrels do in the dark, because we can't see what they're up to. It'd take a lot of (very expensive) work with night-vision stuff to do any research.

 

[Bird_Bill]

Yes, it is interesting. We're equipped with 3 photosensitive cone cell types in our eyes.
Blind to UV light, while virtually all birds have 4. That forth sensitive to UV wavelengths.
Kestrels are believed capable of visually perceiving urine trails, for instance.
Surprisingly, owls aren't well suited for UV. Other specialized night needs are enhanced

 

[Nutcracker]

Surprisingly, owls aren't well suited for UV.

Not really - there's relatively less UV at night compared to longer light wavelengths, as e.g. the moon doesn't reflect it well.

 

[fugl]

Maybe your bird was eating cached prey, something to tide it over until it was light enough to catch something new? The closely related American Kestrel is well known for caching food both in trees and on the ground, and I would imagine the European species does the same.

 

[Nutcracker]

Maybe your bird was eating cached prey, something to tide it over until it was light enough to catch something new? The closely related American Kestrel is well known for caching food both in trees and on the ground, and I would imagine the European species does the same.

I've never heard of European Kestrels caching food, and no mention of it in BWP Concise. I'd doubt American Kestrel is a useful comparison, as (surprisingly!) it is not closely related (Wink et al 2004, scroll to fig. 4 and p.495).

 

[fugl]

I've never heard of European Kestrels caching food, and no mention of it in BWP Concise. I'd doubt American Kestrel is a useful comparison, as (surprisingly!) it is not closely related (Wink et al 2004, scroll to fig. 4 and p.495).

A little googling turns up plenty of references to caching by Falco tinnunculus. Check out this, for example (p. 6., 2nd column):
http://www.tb1.ethz.ch/PublicationsEO/PDFpapers/Wiebe_ORNIS_FENNICA_2000_77_1-9.pdf

The authority for my "closely related" remark was the BNA-online account, dated 2002, which Wink et al. (for the reference to which, thanks) would seem to supersede. Quite a surprise as you say; I shall henceforth regard F. sparverius with new respect!

 

[Rustywater]

Thanks for the replies. Just to add that there was no light for a few miles around. This was well away from anything like that.
My feeling is that it wasn't cached food due to the fact that it would have been an risky place to leave it as the odd vehicle would come along and also due to the difficulty it had flying a few yards showed it was a fairly heavy prey, which I'm frustrated I couldn't see what it was.

 

[paulst]

I have photographed a kestrel caching food and posted pics on here last year I think.

 

[Boro Birder]

Very interesting because ive seen a male Kestrel early one morning just outside Kildale, were i had been staying in a camping barn (Park farm, excellent accommodation by the way if you just like the basics) but electricity, running water, tv with freeview tv, and a separate block of showers and toilets, all for £8.00, Dave Cook, excellent farmer lets me survey all his land for the BTO, NRS, and we used the barn as a base. Anyway one morning before dawn i witnessed a nearby nesting Kestrel, fly to the form of a oak and retrieve half eaten prey, it then flew on to the shower block which i might add is floodlight and i could see he had a half eaten Blue tit, however it did not return to the nest but flew off in the rising sun after finishing it, excellent start to the day, this was in June this year.

 

[Satyrium]

Yes, it is interesting. We're equipped with 3 photosensitive cone cell types in our eyes.
Blind to UV light, while virtually all birds have 4. That forth sensitive to UV wavelengths.

Interestingly, our photosensitive cone cells can "see" UV light - the reason we can't ordinarily see it is because the lens of the eye is opaque to UV. People who've had an artificial lens implanted after a cataract op often find they can then see UV light.

Dave

 

[fugl]

Interestingly, our photosensitive cone cells can "see" UV light - the reason we can't ordinarily see it is because the lens of the eye is opaque to UV. People who've had an artificial lens implanted after a cataract op often find they can then see UV light.

Fascinating. How does the brain of such people interpret "ultraviolet" then, as just another shade of blue/violet or as something completely new & indescribable to the rest of us?

 

[Bird_Bill]

Interestingly, our photosensitive cone cells can "see" UV light - the reason we can't ordinarily see it is because the lens of the eye is opaque to UV. People who've had an artificial lens implanted after a cataract op often find they can then see UV light.

Dave

As I understand, pigment chemicals in our three cone cell types
are electrically excited at a range of roughly 390nm to 700nm.
Those lower wave lengths being coherent violet range.
Ultraviolet meaning "beyond" (the coherent) violet wavelengths

 

[Satyrium]

As I understand, pigment chemicals in our three cone cell types
are electrically excited at a range of roughly 390nm to 700nm.
Those lower wave lengths being coherent violet range.
Ultraviolet meaning "beyond" (the coherent) violet wavelengths

Apparently, this is the typical situation, but it seems that some people show increased sensitivity in the S-cones ( those that are sensitive to the shorter wavelengths) allowing them to detect light at wavelengths shorter than 390nm, like this guy for instance, who, after cataract surgery, can see light down to 350nm.

Dave

 

[Bird_Bill]

Apparently, this is the typical situation, but it seems that some people show increased sensitivity in the S-cones ( those that are sensitive to the shorter wavelengths) allowing them to detect light at wavelengths shorter than 390nm, like
Dave

Thanks, Dave
Guess to answer Fugl in part, perhaps visualizing "a lighter shade of pale purple"- violet. Seems the exception, rather than the rule too. There are those exceptions throughout nature. Without detracting from the initial topic of a kestrel foraging in apparent darkness, questions arise. A persons diet and chemical makeup, compounds such as electrolytes are surely a factor. Another thought, is shape of our lens, and eye in general. Rather than its composition blocking low power levels, lens shape is changed by surgery. Allowing the eye(s) to collimate what could not be seen or visualized before.

 

[Julian Bell]

It might not reflect normal behaviour but I see raptors that normally hunt during daylight hunting at night whilst on migration over the North Sea. See this link for pictures of Peregrine and Short-eared Owl with prey caught during the hours of darkness. There is some lighting from deck which they may use so not sure how relevant this is.

 

[Watts]

I've never heard of European
Kestrels caching food, and no mention of it in BWP Concise.

But there is in the full BWP -
“Food-caching recorded (Kasparek 1974; Brown 1976a; Parker 1977).”

Bill

 

[JWN Andrewes]

I've seen Kestrels hunting pretty late into the dusk, and I've read an article somewhere about a study of remains found at a Peregrine nest including such night migrants as (if I recall correctly) Slavonian Grebe & Little Bittern, the inference being Peregrines habitually hunt after sunset. I wonder if Falcons are better at hunting in low light than we give them credit for, and we don't notice them doing it because its too dark for us to see them at it!

James