There has been much publicity about the programme to re-introduce Cranes to south-west England. Eggs taken from wild Cranes’ nests in Germany have been brought to the Wildfowl and Wetlands Trust’s centre at Slimbridge, Gloucestershire, where the young Cranes have been hatched and raised, before being released in suitable Crane habitat on RSPB reserves in the Somerset Levels. Earlier this week there were reports of four of these Cranes, all colour-ringed and two of them fitted with satellite transmitters, which had returned to Slimbridge under their own steam.
On Wednesday 16 May, while listening out at about 22h00 for nocturnal species at the Gloucestershire Wildlife Trust’s reserve at Ashleworth Ham, I was astonished to hear what I thought was the call of a Crane. I didn’t really believe my ears, until I received a message the next day from Lawrence Skipp, saying that he had found four Cranes, all colour-ringed, doing the Cranes’ dancing display on the Hasfield side of the SSSI. I passsed this message on to the RSPB, who sent me the image shown above, which is what the satellite transmits to them. The fields at Hasfield Ham are clearly recognisable (on a Google Earth image, obviously taken in a dry period, and the blue circle around the yellow and red image confirms that this is a night shot. So this is what the information from the satellite-marked bird looks like, when it reaches the researcher’s computer.
Interestingly, all four birds were back at Slimbridge on Thursday evening, 17 May, but one of them was at Ashleworth again on Friday 18 May at midday, and one was still present at Ashleworth at 0530 on the morning of Saturday 19 May. No computer pictures from these birds as yet!
Clearly the habitatat at Ashleworth and Hasfield on a dropping flood suits Cranes (see picture below of Hasfield Ham, taken on 19 May). This whole area floods when the Severn is high (the course of the Severn is about two fields below the bottom of the satellite picture above). A few days before the Cranes arrived, the whole area would have been under shallow water, about a foot deep with a little emergent vegetation; once the Severn drops, the water recedes rapidly. The RSPB comments that the site looks very like the area where the Cranes have been released in the Somerset Levels. As a matter of fact, when the RSPB was first looking at suitable sites for Crane release, an invertebrate specialist visited this area, to make samples of potential crane food, and to judge whether this might have been a suitable site for crane release; but in the end the Somerset Levels were chosen in preference.