On the weekend of June 15th 2019, we were joined by Drs Ian Henderson and Greg Conway of the BTO to fit satellite tags to some of our young Goshawks both east and west of the Severn. We were delighted to get permission to do this; this is the first satellite tagging project in the county and will provide a glimpse into the secret life of the Goshawk. This is a licensed activity and highly regulated; to get to this stage we have had to apply to an independent panel who hear all the evidence and decide whether we can go ahead.
Photo: Ben Locke
It’s important that the birds are of the right age, weight and size otherwise a tag will not be fitted; the birds’ welfare is absolutely paramount and no chances will be taken.
Photo: Ben Locke
The process is to fit a ribbon harness which fits around the chest of the bird. The tag itself is either 18 grams for a male or 21 grams for a female and this sits on the back of the bird, it also contains a solar panel to charge the on-board battery and a “mobile phone”.
The device transmits the location of the bird, temperature, height, acceleration, direction of travel, battery level, temperature and a few other parameters.
Photo: Ben Locke
Once the tags were fitted there is a tense wait; no information is transmitted as the tags need to charge and register but also the birds are often under cover. But it wasn’t long before we started to receive data…
Males were the first to explore but females are now moving around and the greatest distance moved so far (early September) is a female at around 18km from her nest site.
Some of the birds have gone into farmland and have often used hedgerows to roost or rest, even old hedgerows that have mainly been scrubbed out.
A couple of birds hopped briefly into Wales but only for day trips and moved back quickly.
Some birds have stayed in a tight area – not near their maternal home but they seem to have found an area where there must be food and cover.
One bird is of particular interest, a female who has visited nest sites of other Goshawks. We know it happens in breeding birds because if a pair go missing they are often quickly replaced by a new pair, who seem to be able to find old nests and use them the following year, but it is amazing to see that even at this age they seem to know what makes an ideal nesting area for Goshawks.
Some have come very close to conurbations but not flown directly over them, choosing to move along the edge and crossing a less built-up area.
We have lost two birds at a very early stage, one of the tags has been retrieved and the bird will be sent off for a Post Mortem but there are no signs that the tag played a part in its death. Hopefully we can use the recovered tag next year, the other we are yet to look for. It’s a hard life for a Goshawk and it’s thought up to 60% of birds fail to reach maturity so this is to be expected. We know from our site visits and ringing this year that the weather was not conducive to a good breeding season – birds that went down on eggs early often failed as we had a warm spell but then a very wet, cold and windy spell which would have made hunting hard. The good news is that if the birds that went down later survived the early weeks they had plenty of food available.
As you will see some paths have crossed over each other but as far as I can tell looking at the data the birds were not in the same place at the same time. Not being very scientific a little piece of me would like them to meet although I suspect the consequences of meeting other Goshawks at this stage could be serious for a young bird.
Photo: Semi-fledged Goshawk by Piers Suckling
It’s fantastic to look at these birds’ tracks on Google Maps etc but the real information is in the data and we hope to better understand this as the project goes on.
We are still to retrieve most of our nest cams but hopefully we will during the next couple of weeks and we are crossing fingers that that yields a photo of our first colour ringed bird.
A note about food sources: nest cams that have been retrieved over the last couple of years show squirrel is an important food source which will please foresters. It will be interesting to see if this changes for Goshawks based in the west of the county with the introduction of Pine Martens, I personally doubt it but time will tell.