Subsequent Encounters

I was interested in item 9a on the agenda of the Ringing Committee meeting of April 25 - "BTO Expectations Regarding Generation and Submission of Ringing Data," particularly the requirement to submit retrap data, so I had a look at how we compare to what is expected by the BTO.

The BTO's analysis indicated that the average ratio of retraps to new birds for the vast majority of ringers falls within a similar range, averaging 22%. I guess this would very much depend on where and what species you are ringing. Their analysis focused on 10 common species of Blackbird, Wren, Dunnock, Robin, Long-tailed tit, Blue Tit, Great Tit, Coal Tit, Chaffinch and Goldfinch, for 2018, 2019, 2023 and 2024.

To get an idea of how we compare, I analysed SNRG data submissions for 2025 for these 10 species and the results were - 2866 new birds ringed and 1264 subsequent encounters, = ratio of 44.1%.

The following chart shows how these are broken down per species. 

So, if my methods and calculations are correct, SNRGs new to retrap ratio of 44.1% for these 10 "common garden" birds for 2025 was double the average!

This seems surprising and prompted a bit more investigation. The total of 4,130 birds were ringed across 19 sites, 8 of which are garden sites or sites where supplementary seed is provided. It's no surprise that feeding sites and gardens attract more birds, could our use of these sites account for our high ratio?

Another thought, and one we discuss often, is, could the loss of and deterioration of our "natural" sites, resulting in a focus on feeding sites, affect this ratio? So I did similar searches for several earlier years, and it appears we have been a high retrap ratio Group since the mid 1990s, averaging 37.0% over the targeted years. See chart below for more detail. Communications from the BTO mandating the submission of retrap data, in 2001 and 2005 accounts for some of the increase. 

Mick P 

 

 

Stonechat

I got prepared to take advantage of the small weather window this morning and set a spring trap at Erewash Meadows targeting stonechat. I have seen them regularly in a particular area and where I could watch the trap, this proved to be successful with a young female being caught. Many thanks to Mel, of the Cromford Canal and Codnor Res. group for the photo.

Mick P

 

Broomfield - Saturday 17 January

This weekend we carried out our ninth visit. It was another additional visit and not part of the winter CES. The forecast was for rain but we went anyway and had no rain at all, but it was considerably milder than last weekend. This was probably the reason the catch was not as good. We caught 35 birds throughout the morning. Of these, 18 were retraps. Interestingly we did not catch any Robins after catching 11 in the cold conditions last weekend. We did catch a Great Spotted Woodpecker which is only the second individual we have had at the site. A Tawny Owl was heard calling again when we arrived on site and a Red Kite was spotted twice during the morning flying over.

Kev

Great Spotted Woodpecker (KJH)

 

Broomfield Winter CES Visit 6 - Saturday 10 January

This weekend we carried out our sixth visit for this season’s winter CES, or eighth visit including non-CES visits. A very cold start with snow cover and clear skies.The college was still closed and we had a little difficulty gaining access to the site because the barriers were unusually down, probably a precaution because of the very icy roads and car park. The feeder nets were very quiet all morning but a Redwing call playing at the sports field nets pulled on a surprising 39 Redwing. Unusually they caught all morning despite the nets being lit up by the full sun from dawn and even more obvious against the white snow. The weights of the Redwing ranged from 52.7g to 80.6g. A surprising number of Robins were also caught, 11, no doubt attracted to the bait in the cold conditions. We caught 71 birds in total throughout the morning, of these 19 were retraps. Other observations from the morning included Nuthatch and Tawny Owl calling, Raven and Buzzard.

Kev

 

Box maintenance in the Vale

A beautiful day with hard ground making access easier. I spent it clearing out boxes in the Vale of Belvoir, excavating vast old Jackdaw nests from boxes and getting covered in dust and pellets. Met a few old friends along the way and made a couple of new ones. Also put up a new Kestrel box.

Pete 

 

Orchard ringing - Monday 5 January

On Monday, Kev H and I attempted to catch Fieldfare at an orchard in Linby. There were possibly up to 100 present with many feeding on the windblown apples as we arrived.Rather disappointingly we only caught 1 Fieldfare, along with 1 Redwing, 2 Blackbirds, 2 Starlings, 2 Blue Tits and a Robin.

Mick P