Overhead wires

Not heard about the Raven before either! If correct, that would be a new species for the site. 

A few years ago there was a heron, that initially was alive although suffering a bent/distorted wing. This bird was later spotted dead up near the last pylon (hide end). Before lockdown there was a dead swan near the little marsh/snipe area to the right of the hide. It had been dismembered, but the carcass could have been carried to the spot by a fox. There are still the remains of the Barn owl in the railway hedge trees too. 
I wouldn't be surprised that birds are being killed by the cables. I did a bat survey a few years ago during the summer. Considering the site ecology, I expected a few species. Unfortunately, not one species was recorded at the hide (I did find one Pipistrelle at the entrance/car park, along the hedging bordering the farm). I suspect the overhead cables play a part in keeping bats away from the site, more by the electric field than as an obstacle.
The Raven is a new one, not heard about that before.

I have seen a dead goose/swan ( difficult to determine) under the power lines at Cressy; I know other regulars who have seen a dead gull. I seem to recall a dead Buzzard was found also under cables last year. This week there was a dead Teal but it was not under cables.

Do flying waders and wildfowl crash into overhead power cables, particularly on misty nights? 

It’s one of those ornithological unknowns  ( cf passerine migrants, such as redwings, and wind turbines). 

At the Cress Marsh mitigation habitat near Stallingborough, there is scant evidence to indicate collisions though it is possible that predators such as foxes might be feeding on bird remains before they are detected by birders. 

Cress Marsh is regularly monitored by Emily Drinkell of North East Lincolnshire Council’s ecology department who says she has only twice found avian corpses on the site, in both cases under low cabling near to the pumping station. 

One was a raven, the other, alas for her, was a favourite species - a peregrine. 

In both cases, cause of death was a broken neck.