This is a summary of the activities of Alice, one of my C-permit holding trainees. She is currently working on a PhD at Oxford University and, because of travel, Covid-19 restrictions (between lockdowns), was able to find Hogacre Common Eco Park and get permission to ring there.
The site is adjacent to the sports grounds of a number of Oxford colleges. It is early days yet at the site. It can take a year or so to get the optimum net positions, unless you are lucky.
This is Alice’s summary of her activities on the site in November and December 2020:
Between the 10th November and 15th December 2020, six bird ringing sessions were run at Hogacre Common. Just over 100 birds were processed from ten different species (Table 1, Fig.1). Since these were the first bird ringing surveys at Hogacre, most individuals caught were ‘new’ birds that had not previously been ringed (85%); while 15% of birds were retrapped in a subsequent session. Over 25 species were observed on site during the surveys, with two Lesser Redpoll being a particularly pleasing sighting in mid-November.
Table 1 Number of new and retrapped individuals of each species caught between the 10th November and 15th December 2020.Fig. 1 Number of new and retrapped individuals of each species caught from 10th November – 15th December 2020.
The following list is of bird species seen/heard at Hogacre Common from November – December 2020. It does not include birds flying over that were not using the site: Mallard; Moorhen; Pheasant; Woodpigeon; Collared Dove; Buzzard; Red Kite; Sparrowhawk; Kestrel; Green Woodpecker; Great Spotted Woodpecker; Dunnock; Wren; Blackbird; Song Thrush; Redwing; Fieldfare; Robin; Goldcrest; Chiffchaff; Blue Tit; Great Tit; Long-tailed Tit; Nuthatch; Magpie; Carrion Crow; Goldfinch; Chaffinch; Lesser Redpoll.
Last summer I began regular ringing sessions at the reedbed at Langford Lakes WWT Reserve to monitor the birds using the habitat during the breeding season. Over the last few months I have been curious as to the birds using the reedbed during the winter.
Reedbeds are used as a winter roost by a variety of species, including Reed Bunting, Pied Wagtail and Starling. A session on 9th December last year yielded 19, 1 and 5 of these species, respectively. I was keen to get out again to the site and figured an afternoon session was as good a way to kick of 2021 as any.
I arrived on site just after 1pm and set up the nets playing lures for Pied Wagtail and Reed Bunting. The first round produced 5 birds including a stunning Kingfisher that wowed several passing families (from an appropriate distance of course). After that, each round produced a couple of birds.
All afternoon I could hear Water Rails squealing in the reedbed and elsewhere on site and I thought to myself ‘that would be a nice bird to see up close’. A little while later this showed up in the net:
The first Water Rail I have processed and the first ringed at the site as well as the first ringed by anyone within the ringing group at the ringing group sites since 2009. (Editor’s note: but I did ring my first one on Skokholm in 2019.)
The total catch was as follows: Water Rail 1, Kingfisher (1), Blue Tit 2, Great Tit 1, Cetti’s Warbler (1), Chiffchaff 2, Wren 2, Starling 1, Blackbird 1, Redwing 1, Dunnock 1 and Reed Bunting 1. 15 new birds from 11 species and 2 re-traps form 2 species giving a total of 17 birds from 13 species.
Aside from the Water Rail the two Chiffchaff were nice to catch. This migrant is wintering in the U.K in increasing numbers. And of course, Kingfishers are always a joy to see up close.
Overall a session defined by its quality rather than the quantity. What a fantastic start to the year.
A pretty excellent December: our biggest catch in that month since the group split at the end of 2012.
Clearly we were much more active this December than in previous years: just 10 sessions last year. This is almost certainly a by-product of Covid-19 restrictions. Regardless, it is a pretty decent catch. Looking at those species that we have more than doubled since last year (because we have done more than double the number of sessions), it is great to find an increase in Long-tailed Tit numbers. Alongside that we have definite increases in numbers of Nuthatch, Great Tit, Dunnock and Starling.
Compared with last year, the species added to the list for December were: good numbers of Reed Bunting, plus Jay, overwintering Blackcap, overwintering Chiffchaff, Goldcrest, Pied Wagtail, Stonechat, Lesser Redpoll and Treecreeper. Missing from last year’s list is Grey Wagtail and Meadow Pipit.
With the forecast being for a bit of snow overnight but an icy start to the morning, I was hopeful that it might be possible for us to run a session at Somerford Common. In the event, the temperature was just on freezing but there was no wind, so no wind chill factor. I decided we could set the nets: just the 4 at the feeding station and the Redwing nets on the main path. The feeding station was topped up on Thursday, ready for today.
On my way to site, as I was approaching the entrance to the car park at Somerford Common on Stopper’s Hill, I saw my first bird of the new year: a Woodcock. That was a good start!.
I was joined by Lucy for the morning. The birds started arriving whilst we were still setting the nets, even though it was only just daylight. It was busy between 8:00 and 10:30 but died off quickly after that. There was a light snow shower between 8:30 and 9:30 but that just warmed the place up, and didn’t even settle on the nets.
Having missed out on Redwing at Ravensroost and Red Lodge, it was good to find that there are still some about. We caught eight and a couple of Blackbirds, in the appropriate net ride with a lure playing.
The list was: Nuthatch (1); Blue Tit 6(8); Great Tit (8); Coal Tit 2; Marsh Tit 1(4); Robin 1(3) Redwing 8; Blackbird 1(1); Chaffinch 2(1). Totals: 21 birds ringed from 7 species and 26 birds retrapped from 7 species, making 47 birds from 9 species.
It is always nice to start the year with a Marsh Tit or two, to start with five, including a new bird was a real bonus.
We cleared away at 11:30 and were off site by midday – the benefits of not setting up lots of nets.
I started my ringing career in January 2009. Having been a keen birder up to then, and Ravensroost Wood being one of my key local patches since I moved into the area in 1997, I was keen that we should get to ring in the site. I set about persuading the Wiltshire Wildlife Trust to allow us access. I provided the rationale, and swapped loads of data with the Trust, from my 11 years of birding there, and they gave me the information gathered from regular breeding season surveys that had been carried out, and the agreement was reached. My trainer provided a project plan and a risk assessment, and we gained access after Natural England approval (it is a SSSI) and first ringed there in July 2009.
To be fair, it wasn’t my trainer’s favourite site, and it was agreed that, when I got my C-permit and could take it on, it would become my site to manage and work. I got my C-permit in June 2012 and took over the site, with a new project plan, in September 2012. Soon after starting work there I bumped into a staff member from the Forestry Commission and I enquired about getting access to their Braydon Forest sites. They were really helpful and welcoming and I got access to Somerford Common, Webb’s Wood and Red Lodge Plantation soon after. Since then the vast bulk of my ringing has taken place in this area.
Unsurprisingly, the commonest species in my catch is the Blue Tit, Cyanistes caeruleus. People who don’t understand ringing often ask “Why bother with such a common species?”. Some ringers choose not to ring them (at 27p per ring cost one can understand the reluctance for those who do not get external funding for their rings, although I largely fall into that category, my view is that if I have “inconvenienced” them by catching them, the least I can do is ensure that we get some data back from them). The argument itself is fallacious: once upon the time the BTO would not allow House Sparrows, Passer domesticus, to be ringed, because they were so common. That worked out well, didn’t it? Besides, it seems the whole rationale for the Edward Grey Institute at Oxford University is studying Blue Tits, and if it is good enough for them, who am I to argue?
The key thing about Blue Tits: you are going to get a good sample size upon which to make judgements on trends. So, with the vagaries of the weather disrupting my ringing activities more often than I would like at the moment, I have been having a look at my Blue Tit records since I took over the ringing in the Braydon Forest, with complete years from 2013 onwards. The numbers caught have been as follows:
Fig 1: Number of birds ringed by year by age group
This year’s numbers have possibly been skewed a bit by lockdown, but only really in March / April, and I have managed to get sessions in every wood in just about every month of 2020.
One of the perennial questions ringers have differing opinions on is about sexing Blue Tits on wing length. They are a sexually monomorphic species, so the only reliable way of telling the sexes apart is in the breeding season, when the females develop a pronounced brood patch and the males cloaca becomes engorged and is known in the trade as a cloacal protuberance. I have analysed my data for males and females sexed by their breeding condition and mapped the numbers against wing-length to see whether it is possible to reliably sex them on that biometric outside of the breeding season:
Fig. 2: Number of identifiably male and female Blue Tits ringed by wing-length
As you can see, a Blue Tit with a wing-length of 62 mm is almost certainly female, and an individual with a wing of 66mm and longer is almost certainly male. In fact, amongst my catches I have had 1 male with a wing of 62 mm and one female with a wing of 66 mm. Some ringers look at a combination of wing-length and brightness of plumage but I prefer to err on the side of caution.
With Blue Tit broods being typically 8 to 10 eggs, with perhaps 6 to 8 nestlings surviving to fledging age, one would expect the numbers of juveniles ringed each year to be significantly higher than the number of adults and, as figure 3 shows, that is usually the case. From looking at figures 1 and 3, it is clear to see that 2016 was a terrible year for Blue Tits in the Braydon Forest. Not only were the numbers down significantly across the board, but the breeding success was remarkably poor.
Fig 3. Numbers of juvenile and adult Blue Tits ringed by year
It was a particularly wet spring in 2016, and the summer wasn’t much better. Other species also suffered in the Forest, particularly Long-tailed Tits, Aegithalos caudatus. Whilst Blue Tit numbers have recovered somewhat, Lotti’s are taking a longer time to build up again. However, 2020 looks to be the second worst for juveniles and the best year for new adults.
Whilst the bald numbers in figure 3 are themselves of interest, what really stands out is when you show adults vs juveniles as a proportion of the total, as shown below in figure 4:
Fig 4. Ratio of juvenile to adult Blue Tits ringed by year
As mentioned above, this shows that 2020 has been a depressed year for juvenile production as a proportion of the whole, but not as bad as 2016 was. What is surprising is that this was not how it felt whilst ringing juvenile birds in the summer, so I had a look at how this split might have occurred by analysing the proportion of birds ringed in the breeding season (May to August inclusive), as shown in figure 5, and those ringed in the early winter (October to December inclusive), as shown in figure 6.
Fig. 5: Ratio of juvenile to adult Blue Tits ringed in the breeding season
This shows that, proportionately, 2020 in the breeding season was very much in line with all years, except the remarkably different years of 2016 and 2017.
Fig. 6 Proportion of juvenile to adult Blue Tits tinged in early winter
Figure 6 does show the ratio to be depressed compared to all years except 2016, but not significantly so. So why the overall variation in numbers? I thought that it might have something to do with adult survival over the winter of 2019 / 2020 being better than in previous years. So I have graphed up the numbers of birds ringed over each complete winter, using the months November to December in the preceding year and then January to March in the following year.
Figure 7 shows the numbers of juveniles and adults ringed in that period:
Fig. 7: Numbers of juveniles and adults ringed over a full winter
As you can see, these numbers are second only to the winter or 2013 / 14. The proportion of juveniles to adults is also somewhat interesting:
Fig. 8: Proportion of juveniles to adults ringed over a full winter
Essentially, it is consistent with all previous years except 2012 / 13, which was the first year of study, and the winter following the awful breeding season in 2016. I suppose that what I am saying is: I have no idea what has caused the change in the balance this year. Blue Tits might be common, but they are interesting.
The last few sessions have been at my usual woodland sites, with feeding stations in place. This has meant that they have been based very heavily on large catches of Blue and Great Tits.
As it was forecast to be a bit windy this morning I knew I would be woodland based. To be honest, I wasn’t really looking forward to another big catch of Blue and Great Tits: you can have too much of a good thing. So I took the decision to head for the north western area of Somerford Common. This part of the site is on the edge of the large commercial conifer plantation. Being an ad hoc visit, there are no feeders set up.
The underfoot conditions were appropriate for a re-enactment of the third battle of Ypres, also known as Passchendaele, so I was a little apprehensive about being too busy, as I was working solo. Because of that, I set up just 2 rides: 2x 18m and 3x 18m, and put on lures for Redwing (L1, L2 and L3). Just like at Red Lodge on Thursday, we didn’t catch a single one.
In fact, it was a really slow start: I didn’t catch any birds between 7:30 and 9:00, and was thinking that I should have stayed in bed. Instead I changed the lures: L1 to Coal Tit and the others to Lesser Redpoll. I didn’t catch any Lesser Redpoll but the Coal Tits did respond.
At 10:15 I changed L1 and L3 to Goldcrest, and they started to arrive in reasonable numbers. In the end it was a decent catch of Blue Tit 2; Coal Tit 13; Wren 3; Robin 1; Blackbird 1; Goldcrest 11. Total: 31 birds ringed / processed from 6 species.
So not the biggest or most varied of catches, but a good relaxed session and an excellent opportunity to practice ageing Coal Tits (it’s all in the greater coverts!).
I packed up at 11:30 and was off site by 12:15. I have a feeling that this will be my last session before Christmas.
On Friday last I went to set up a feeding station at the Forestry Commission site at Red Lodge, planning to get out to the site this Thursday. The weather in the run up to Christmas is pretty bad, with Tuesday, 15th and Thursday, 17th currently looking like the only days likely to be dry and not too windy before Christmas Eve. Unfortunately, on arriving at the Red Lodge site I found that the standard padlock was not in use, and there was a combination padlock in place.
Rob, the Beat Forester, sent me the code and so, after my session at Lower Moor Farm on Tuesday, I went over to Red Lodge and set up the feeders: peanuts in two and a seed mix in the other two. Ironically, had I looked closer on Friday I would have seen that the contractor for whom it was set up hadn’t actually used it to lock the barrier, had just balanced the barrier on the lock post and I could have got access on Friday.
For this morning’s session I was joined by Lucy and Alice. We had a late start: 7:30, but were only setting up a few nets, which we had managed by 8:00. I warned them that, with the feeding station only being set up Tuesday lunchtime, the catch probably wouldn’t be huge. 101 birds later my bluff was called!
The first two birds out of the nets were a couple of Blackbirds. Needless to say, the bulk of the catch was made up of Blue and Great Tits, but the catch was a bit more varied than that. However, pretty well uniquely for my sites this winter, there wasn’t a single Redwing in the catch, despite 2 lures playing for most of the morning.
At 9:50 we had a small feeding flock of Long-tailed Tits caught in one net. We processed them and returned them to the catching bags so that they could be released together. I love watching them fly off, buzzing their contact calls as they disappear into the trees.
At 10:30 I changed the Redwing lure for a Goldcrest one, and we immediately caught a small number of them. They do come readily to the lure, so I never start it off before 10:30, until they have had plenty of time to get a feed in. Not that I have ever had a problem with Goldcrest’s being adversely affected by being caught and processed, but I never want to.
The list for the day was: Nuthatch 1; Blue Tit 39(14); Great Tit 13(2); Coal Tit 3(2); Marsh Tit (2); Long-tailed Tit 7(1); Wren (3); Robin 7; Blackbird 3; Goldcrest 4. Totals: 77 birds ringed from 8 species and 24 birds retrapped from 6 species, making 101 birds processed from 10 species.
The last bird out of the net was a Blackbird, immediately preceded by a Nuthatch.
Nice to top and tail the catch with some Blackbirds.
We started to pack up at just gone 11:30, just as the wind got up and were off site by midday (the benefits of not setting lots of net and having a crew to help).
With the forecast being pretty unsettled for this week, I decided to take advantage of the dry forecast for today and paid a visit to Lower Moor Farm. I was working solo – but I didn’t spend the morning on my own.
I was joined, all properly socially distanced, by some of the children from the Care Farm, with their carers for the day. One youngster was very keen on birds. He backed that up by identifying several of the species I was able to show him. He told me that it was his birthday in 5 days and that this was his early birthday present! Unfortunately, because of the precautions I couldn’t show him how to safely hold and release a bird.
His younger brother was also there, and his carer told me that he had never stayed that still for that long: which was evidenced by his sheer dynamism as they left. I know it is a cliché but children benefit so much from being out in nature.
I set up just 5 nets in 2 rides: it wasn’t going to be a big catch as I don’t set up feeding stations at Lower Moor, but it was a decent catch. The highlight had to be my first overwintering Chiffchaff of the year:
The obligatory Blue and Great Tits dominated the catch, but it was of reasonable variety. The Redwing were present, not in such good numbers as elsewhere, but there are probably better feeding areas for them on other parts of the site.
A female Bullfinch was another highlight. The biggest gripe of the photographers at Lower Moor is that they can never find a Bullfinch to photograph that doesn’t have a ring on it. This is one more they won’t want to photograph:
Today’s catch was: Blue Tit 3(3); Great Tit 4(4); Long-tailed Tit 2(1); Wren 1; Dunnock 1; Redwing 3; Blackbird 2; Chiffchaff 1; Goldcrest 3(3); Bullfinch 1. Totals: 21 birds ringed from 10 species and 11 birds recaptured from 4 species, making 32 birds processed from 10 species.
I started to pack away at 11:30. Quite astonishingly, whilst absolutely surrounded by clear blue sky, a small cloud decided to drop its bounty of rain exactly on my ringing station and I got wet putting it all away. Typical!
Ringing In The Braydon Forest & Beyond 