Monday 23 July 2012

A WATERY DIVERSION

With the appalling weather lately, and it being breeding season, the bird photography has taken a back seat. There haven't been many insects to chase either, so I had a dabble in the garden pond, which certainly has plenty of water in it. It's full of tadpoles that don't seem to be developing beyond the two-legged stage, and there are some newts as well. I had a dredge around with a net to see what was lurking, and then tried a bit of dark-field macro photography on the results. This involves placing semi-opaque or translucent subjects on a glass stage over a black background, and lighting from below at 45 degrees from the camera axis. In theory, one gets an image with a pure black background and light shining through the subject. It's not as easy as it sounds. The water has to be spotlessly clean, as all the detritus shows up as bright spots, so you spend an inordinate amount of time cloning-out the unwanted bits, but the end result can be quite nice. One of the problems is that unless you are an expert on freshwater life, you don't know what you are photographing, but it's fun!

Newt sp. elt: this is a very small one - about 5mm long.


Here's one a bit older - the gills are obvious, and in contradistinction to frog tadpoles, the forelimbs develop first. The hindlimb buds are seen as bulges further down the body.


Combining the dark-field illumination with a little fill light from above brings out more detail.


Crustacean sp.  I've no idea what these tiny shrimps are called. The larger one is about 7mm long. I'll have to buy a book!




Water Beetle (possibly Family Dytiscidae). Solid subjects give a rim effect.


But with a little fill light from above, become more life-like, but it shows the dirt more. I like to think of this as the "Starship Coleoptera".


All the images were taken with a Canon EOS 7D, 50mm F2.5 macro lens with 25mm extension tube linked to an old Sunpack ring flash that's been cluttering up my cupboard for years. Even if you get accused of hoarding, never throw anything away!
None of the animals were harmed by this activity, and went straight back in the pond.



RINGING

I'm not a ringer, but have the greatest admiration for those who are, and try to see what they are up to when time allows. If you've read any of Gilbert White's "Natural History of Selbourne", you'll know that in the late 1700's, it wasn't known whether birds left our shores for winter, or actually hibernated here in cracks and crevices. The matter was only truly resolved when we started ringing, and the contribution to our understanding of bird ecology by ringers has been massive, especially in relation to mapping migration routes and preserving habitat. With climate change, it's just as important today, but as satellite tags get smaller and lighter, it may become less so in future. Two late night sessions recently have produced results.

Petrel ringing involves enduring a cacophony of a tape-recording of the bird's breeding colony, projected through a loudspeaker out to sea, to attract birds feeding offshore into a mist net. It's a technique of hit and miss with low returns - one or two birds in a three hour overnight session is a good catch, but it allows close inspection of these delicate little seabirds. Storm Petrel (Hydrobates pelagicus) is the commonest catch, but an occasional Leach's Petrel (Oceanodroma leucrrhoa) turns up in the net. One always lives in hope of something rarer.


Storm Petrel.


This image was taken with a Canon EOS 7D with 24-105mm F4 zoom, and built-in flash. It's always a bit hit and miss in the dark - the bill isn't sharp.

Nightjar (Caprimulgus europaeus) ringing in Langdale Forest isn't too dissimilar - nets set at dusk and a tape of the birds churring, and a patient wait fending off the dreaded midges. Again, a single bird may represent a successful night, but at least the vigil isn't as long, usually being over by midnight. Inspection of the bird in hand reveals it's superb cryptic plumage, and a small "comb" on it's middle toe, which is used to clean insect debris from the ictal bristles round the base of the bill. 

Nightjar.




The bird is a second year male, as it only has two white spots on it's primary wing feathers. The images were taken as for the Stormy above.