Wednesday, 31 March 2021

Charter Wood and its surroundings: year two of intensive monitoring

Another year of monitoring at Charter Wood is over. This 35-acre wood on the western outskirts of Norwich was planted in 1994 and is managed by the Norwich Fringe Project. The wood is flanked by horse pasture and a 50-acre arable field that has been left fallow over the last year. Ecological consultants were out surveying the area recently, and it turns out the arable field is earmarked for yet more houses. Disaster for the breeding Skylark and wintering population of Woodcock, not to mention the increased disturbance in the woodland itself. When it’s your patch the losses are felt more keenly, yet it’s easy to forget the spot our house (built in 2003) stands upon was once home to breeding Turtle Dove and Nightingale, both now gone from the local landscape. 

Putting that aside, it’s safe to say when I wrote the blog a year ago, I would not have imagined the year that was to follow. Thankfully a lion’s share of the monitoring we do is from our garden which backs onto the woodland, so even through lockdown we were lucky enough to continue our ringing activities here. The arable field, however, has become very weedy and has made our lamping work much more difficult there resulting in a poor season (we also couldn’t visit through much of lockdown). Ringing effort comes predominantly from a single 18-metre mist net starting at our back fence leading into the woodland. With additional nets sometimes used in the garden, and around Charter Wood/the horse pasture for targeted catching (e.g. for Meadow Pipits). Supplementary feeding was supplied year-round but was greatly reduced during summer. We also did some dazzling in the arable field. 

Map of the Charter Wood area

Charter Wood and the garden by the numbers. 

Between March 31st 2020 and March 31st 2021, we ringed a total of 1323 birds across 33 species within the Charter Wood area and encountered 1559 unique individuals. The number ringed is a bit down on last year, but as last year was the first year of ringing here that’s not too surprising. Unsurprisingly with feeder-based ringing, Tits dominated the catch once again with Blue and Great Tits making up 47% of the total birds ringed. However, our finch numbers also seem healthy, particularly Greenfinch (193 unique inds.), Chaffinch (173 unique inds.), and Goldfinches (103 unique inds.). 

There are a bunch more detailed graphs at the end of the blog of what we have found for those of us that enjoy a graph or two. 

Table: Birds ringed in Charter wood, Species in bold were new for the site. Treat percentage changes with care, effort isn't standardised.

SpeciesNewRetrapsTotalUnique inds.
Unique inds.
Blue Tit448455903540up 15%472
Great Tit145273418202down 33%302
Greenfinch17534209193up 16%167
Chaffinch15452206173up 16%149
Blackbird623910177down 25%102
Goldfinch9713110103up 18%87
Dunnock37427947down 18%57
Robin38407847down 13%54
Long-tailed Tit22295129down 31%42
Blackcap2312423up 92%12
Brambling2102121up 525%4
House Sparrow1901919n/a0
Meadow Pipit1301313n/a0
Chiffchaff85139down 36%14
Wren73108down 20%10
Skylark9099down 40%15
Great Spotted
5495down 38%8
Goldcrest8088no change8
Bullfinch5276no change6
Woodpigeon4044down 73%15
Collared Dove3033down 82%26
Jay3033down 80%15
Song Thrush3033up 50%2
Marsh Tit2022n/a0
Lesser Redpoll2022n/a0
Coal Tit2022down 82%11
Treecreeper2022no change2
Woodcock1011down 89%9
Sparrowhawk1011down 50%2
Redwing1001no change1
Lapwing0000down 100%1
Starling0000down 100%1
Reed Bunting0000down 100%2
Stock Dove0000down 100%2
Magpie0000down 100%2
0000down 100%1
Total132399223151559down 3% 1601


  • 6 new species ringed for the site this year.

  • Use of some trap types such as potters and maze traps was reduced this year, and combined with a mast year for acorns in the area saw our catch of species such as Jay reduce substantially.

  • The wintering flock of Greenfinch held strong for another year, and probably saw a small increase in numbers (~250–300 in the wood). No sign of Trichomoniasis is also hugely encouraging. 

  • A surprising drop in Great Tit numbers, with unique indivduals down 33% (100 less inds.). I'm yet to come up with a decent explanation for this.

  • Chaffinch numbers were strong and we saw a bigger passage of birds than previous years. A Norwegian ringed bird being one of the highlights of the year. 

  • During the Chaffinch passage we also saw a fantastic passage of Brambling, with a very surprising 21 ringed. Well up on the 4 last year. We also got our first Redpoll and Siskin ringed, both being surprisingly infrequent passage visitors to the woodland.
Male Brambling
  • The heavy snow in February brought Fieldfare to the garden, and with one ringed it was probably the surprise capture of the year. 
  • Charter Wood doesn’t attract large numbers of warblers in general, and this is reflected in the relatively modest numbers of Chiffchaffs and Blackcaps that we ring annually. This year saw a better passage of Blackcaps, but Chiffchaff numbers were slightly down. 

  • We had 7 controls (ringed by someone else) of birds in the last year. The best two being a Norwegian Chaffinch and a Dutch Blackbird.  The rest (2 Blue Tits, 2 Greenfinches,  and a Bullfinch came from within Norfolk).
Dutch Blackbird (top) and Norwegian Chaffinch (bottom)
  • We had another 3 birds reported as killed by local cats, this is more than likely an undercount of the true number.

Charter Wood nest box scheme 

Our nest box scheme got off to a good start in 2020, with lockdown restriction lifting just in time to allow us to ring the chicks. Chicks ringed were included in counts of new in the above table, but overall, we ringed 268 Blue and Great Tits from 33 nests.
Here’s an overview of the project results: 

We recently made repairs for the Great Spotted Woodpecker and Grey Squirrel damage to boxes (17 boxes were damaged through the winter), and we put hole guards on those boxes to help reduce future damage. Our first checks for the 2021 season are imminent, so fingers crossed for another good season. 

Graphs of Charter Wood ringing 

Captures by month 

There are two clear peaks in captures through the year, one just after the breeding period (lots of new young birds moving about), and one in mid-Winter (birds congregating into wintering flocks and using feeders more).

Captures by month corrected 

Correcting for the amount of trapping effort each month isn’t very easy when you operate varying trapping methods (some of which are passive such as maze traps). A very rough way of correcting for effort is to simply calculate number of birds caught per trapping day (where a trapping day is considered a day where at least one individual was trapped). 

Species richness by month 

Diversity is reasonably steady through the year 

Retrap plot

Most birds don't get re-encountered, even with the large number of retraps we get at feeder sessions.

Thursday, 31 December 2020

UEARG ringing report 2020

There are a lot of reasons to be pretty dour about 2020 and the months to come, but this isn’t the place for that. Despite periods in which ringing was restricted to our gardens, curtailed by group size limits, and Covid related decreases in group funding; 2020 was a fantastic year of ringing for us and was one of the groups most productive years on record.

2020 saw us collect 8180 records of 6365 unique individuals consisting of 5540 birds ringed, 2199 retraps/controls, and 441 sightings (metal or colour ring reads in the field). It was also the most diverse year with a total of 79 species recorded, 73 of which were ringed, 3 were only recorded as retraps/controls and 3 came only from sightings. 3 species were firsts for our group: Little Grebe, Water Pipit, and Whinchat, and several others were the first the group have caught for many years such as Tawny Owl, Coot, Herring Gull, and Little Owl amongst others. Whilst it may have been a diverse year in terms of number of species, as much of our ringing is based at woodland feeders (particularly in the winter), Blue Tits romp home and take the top spot once again with ease. 

Monthly captures, shaded region was full lockdown period with ringing restricted to gardens

Blue Tit113494302077
Lesser Redpoll54920551
Reed Warbler438190457
Great Tit3765070883
Sedge Warbler330150345
Reed Bunting15960165
Long-tailed Tit1321420274
Mute Swan9550329474
Bearded Tit5920079
Coal Tit30820112
Meadow Pipit280028
Pied Wagtail (yarrellii)470047
Cetti's Warbler200020
House Sparrow190019
Black-headed Gull1515066
Sand Martin140014
Great Spotted Woodpecker114015
Willow Warbler91010
Song Thrush9009
Collared Dove8008
Yellow Wagtail6006
Jack Snipe5207
Green Woodpecker5005
Greylag Goose501015
Garden Warbler4004
Lesser Whitethroat4004
Water Pipit4004
Marsh Tit38011
Canada Goose31711
Little Owl2002
Stock Dove2002
White Wagtail (alba)1102
Common Redpoll1001
Grey Wagtail1001
Herring Gull1045
Little Grebe1001
Tawny Owl1001
Grasshopper Warbler0101
Barnacle Goose001515
Lesser Black-backed Gull0011

Captures of most species were up from last year as a result of increased effort and improved understanding of how to work the sites from those of us who joined the group relatively recently, but also reflect trends seen nationally such as the eruption of Lesser Redpoll this year that saw us catch 551 (for reference only 204 were caught across the entirety of Norfolk in 2019). 

The group joined three colour ringing projects this year to improve on the scientific outputs of our work, whilst the existing Jay colour ringing project has had limited success (perhaps unsurprisingly, but if you don’t try you’ll never succeed). The most prolific of these projects has been the Norwich Swan Project, which has seen us colour ring 124 Mute Swans across Norwich and generate over 500 sightings since we started in July. We also started colour ringing Black-headed Gulls and whilst we only catch modest numbers (15 adults caught by hand and a handful of chicks that were metal ringed on non-UEARG rings), we hope to build upon this in the coming years. Finally, we joined the national Water Pipit colour ringing project after catching two individuals at Cantley in late Autumn, and have subsequently colour ringed a further two individuals. Please keep an eye out for any colour ringed birds and report sightings, however menial you think they may be.

Water Pipit

Data will continue to come in over the next months for birds we have controlled in 2020 or have been recovered elsewhere, but in total we caught 16 controls this year (excluding Mute Swan controls from a local ringer outside our group that is also active in Norwich and local RSPCA rescue birds) and have had 14 recoveries so far (excluding colour ring sightings). We’ve also had 63 >1km movements between our own sites but these were mainly movements of colour ringed Mute Swans. Beyond those Swan movements, we also record several movements between Charter Wood and UEA Campus (~3km). Here’s a map of 2020 controls and recoveries we have data for so far, excluding Mute Swans:

This year we ringed at 34 sites across Norfolk (and a little bit of Suffolk), but the vast majority (77%) of records come from just 5 main sites (Charter Wood, UEA Campus, Horsford Wood, Cantley Beet Factory, and Waxham). Charter Wood, UEA Campus and Horsford Wood are all woodland feeder sites primarily worked in the winter months, Cantley Beet Factory is an extensive reedbed in the factory settling pools primarily worked from late summer to early winter, and Waxham is coastal scrub and woodland on the east coast worked through spring and autumn passage.


551 Lesser Redpolls is a great total for us, all of which were caught at Waxham on the east coast during passage. 343 caught in one day (October 17th) gave us our busiest single ringing day we can remember (393 birds in total).
Only one Common Redpoll was caught amongst that lot was less than expected, but still nice to get. Unfortunately, poor weather curtailed our efforts at Waxham during Autumn passage and we probably lost the final two weeks of passage ringing as a result.

Common Redpoll

Perhaps most impressive was that despite Red-flanked Bluetail, Red-breasted Flycatcher, 2 Pallas’ Warblers, and multiple Yellow-browed Warblers all turning up within ~1km of our Waxham site (which is scrub and woodland right on the east coast), and 12 visits during that autumn passage period, not a single scarcity was ringed. Fingers crossed for 2021!

Just the one foreign control from Waxham this year, but it was a cracker. This first-year Kestrel from the Netherlands may well be our bird of the year but we are still waiting for details on where and when it was ringed. This is the 64th Dutch Kestrel to be controlled in the UK, but not all of these will be trapped birds such as ours (i.e. some could be dead birds or ring reads in the field).
First-year male Kestrel from the Netherlands
Our other foreign control this year was a Black-headed Gull caught by hand in Wensum Park. This bird was ringed in Denmark but we are still waiting for further details.
Black-headed Gull from Denmark

Here’s some pictures of our personal highlights of 2020:

Little Grebe, dazzled on Bowthorpe Marsh
The groups first Whinchat
Little Owl, one of the breeding indivduals on UEA campus
Jack Snipe
Common Redstart
Tawny Owl
Yellow Wagtail
Male and female Stonechats
Green Woodpecker
Bearded Tit
Lesser Whitethroat
Grey Wagtail
Stock Dove

Finally, a massive thank you to everyone who helped out with UEARG ringing activities this year not least the many land owners and managers who grant us access and permissions. Group sizes were restricted this year but our ringing was a cumulative effort across 15 ringers. Our ringing would also not be possible without the continued support of UEA and Dr Iain Barr.

Wednesday, 11 November 2020

Norwich Swan Project - 6 months in

UEARG has been ringing swans in Norwich for many years, but not typically in big numbers. Last winter we ringed 20, which I thought was pretty good, but the metal rings we put on typically don't get a lot of returns and unless the bird is very close can be tricky to read without recapturing the bird. With colour rings, amassing additional encounters is easier, the public can get involved, and most importantly it's less hassle for the bird. I therefore approached Mike Reed to join his national colour ringing project on Mute Swans, in the hope of setting up a mini project within his larger project. With the Norwich Swan Project (as I have named it), our aim is to get a better idea of how swans use Norwich waterways and get a better assessment of how well the population is doing.

One national lockdown later I set about getting swans across Norwich colour ringed, hoping I could match the 20 I did the previous winter. Six months have now passed and it's fair to say my expectations have been well and truly surpassed. To date we have colour ringed 123 swans across Norwich, amassed over 400 sightings, across 17 sites, and we are only scratching the surface of assessing the life histories of a species that can live into their late 20's. 

The first of many! When reporting make note of the ring colour (orange), the writing colour (black), and the code (4DUA)

Here's a map of all those encounters, each point is a location that a swan has been ringed or sighted with darker points indicating more encounters. The lines show movements between locations, with darker lines showing more movements. 

The majority of our catching takes place in the east of the city at Whitlingham Country Park, Carrow Road Bridge, and Thorpe River Green. Three sites I've affectionally dubbed the Swan triangle. As a result, the points and site links here are stronger but it does reflect the much higher density of swans in this area (hence why we do so much catching here). Anyone passing these sites this year will be familiar with groups of 30+ swans eager for some food. The Carrow Road Bridge area in particular has recently become a hotspot for swans in Norwich due to people feeding from their balconies that overlook the river.

Only 12 of our 123 swans colour ringed this year were hatch year birds, and the majority of these turned up late in the season likely dispersing from their natal sites. We think this may point towards low breeding productivity of swans within Norwich itself, and is an area we want to explore further next year. If you know of any nesting locations we'd be keen to know about them, especially next spring when swans start to pair up and nest build.

We also need more sightings! If you are in Norwich and you see a colour ringed swan, please stop and give it a read if you can and submit your sightings to mike.reed2017 [at] or contact me directly through our Twitter, Instagram, or Facebook pages. It doesn't have to be a long distance movement to be interesting to us, all data is good data!

Wednesday, 23 September 2020

I Cant-ley believe the season is over already

As we rapidly approach October our premier reed bed site suddenly feels very quiet, just as our coastal migrant site starts to liven up. With that, our period of more intensive ringing at Cantley reed bed is over for another year. It’s been an interesting season, but a small team of us managed 12 sessions between July and September getting a flavour of the amazing passage of Acrocephalus warblers that pass through the site on their way to Africa, mostly for the first time (~96% of Acros ringed were first-year birds). 

Misty mornings and late nights with swallows are regular features of reed bed ringing

High water levels and plenty of sunshine produced a very good reed growth year and probably helped bump bird numbers up where the high water levels provide extra predator protection. That being said, Swallow roost numbers were down partially as a result of up to 6 Hobbies present in the area which moved the Swallows to alternative roost sites later in the season.

In total 1,402 birds were processed, of which 1,349 were new and 3 were controls. Acros made up 766 (57%) of the new birds, a total we were very pleased with and with 328 ringed it was a very good year for Sedge Warblers for the site. Bearded Tits and Cetti’s Warblers also seemed to have a good breeding season, and are always a pleasure to share the reed bed with. 

Species totals 2020:

SpeciesNewRetrapsUnique inds.Total
Reed Warbler43819440457
Sedge Warbler32815329343
Bearded Tit48135261
Reed Bunting5315454
Blue Tit1811819
Cetti's Warbler1501515
Sand Martin1401414
Yellow Wagtail6066
Garden Warbler1011
Great Tit1011

A first-year male Whinchat caught on the 31st August was probably our bird of the season, being the first for UEARG.

With 52 different individual Bearded Tits caught this year (48 new), they are clearly doing well on site and can often be heard pinging away in the reed bed.

This juvenile male Kingfisher was another highlight of the season and a species you can never get bored of seeing up close.

Yellow Wagtails were probably present in smaller numbers than previous years this season, reflected in just 6 being ringed. A far cry from the 104 ringed in 2014! 

A good year for Cetti’s Warblers that as you’d expect are often heard belting out their song around the site. 15 individuals ringed being a good total here.

A bumper year for Sedge Warblers passing through, 329 different individuals encountered including this monster that came in at 21.2g (the average on site this season being 11.7g)

Reed Warblers dominated the catch in almost all sessions this season

A special thank you to British Sugar that give us access to the site, and to Kirsty, Jack, Max, Alex, and Adham for their hard work helping on site this year.

Tuesday, 31 March 2020

Charter Wood and its surroundings: One year of intensive monitoring

In March 2019 two UEARG members (myself & Kirsty) moved into our new home, which fortunately for us backs onto Charter Wood. This 35-acre wood on the western outskirts of Norwich was planted in 1994, and is managed by the Norwich Fringe Project. The wood is flanked by horse pasture and a 50-acre arable field with corn grown last year and the field was left as a stubble through winter. The group have previously not ringed here, so we weren't sure what to expect. I’m lucky enough to be able to work at home with my computer-based PhD (even before Covid-19!) which has afforded me the opportunity to monitor the woodland pretty intensively over the past year. It's not a particularly busy ringing site, and this enables me to balance ringing with work (with some additional evening catch-up where needed).

Ringing effort was mainly in the garden and a single 18-metre mist net just the other side of our back fence leading into the woodland. Supplementary feeding was supplied year-round but was greatly reduced during summer. We also dabbled in a bit of dazzling in the stubble field in late-winter.

View from the ringing room overlooking Charter Wood.

 Charter Wood and the garden by the numbers.

Despite the woods relatively young age we’ve been pretty surprised by not just the numbers, but the diversity of species ringed in the past year. For me this is a nice signpost that these relatively immature planted woodlands, especially when managed as Charter Wood is, can be a great ecological success. Here is a brief overview of totals, but at the end of this blog I’ll throw in a bunch of more detailed graphs of what we have found for those of us that enjoy a graph or two.
Between March 31st 2019 and March 31st 2020, we ringed a total of 1,568 birds across 27 species within Charter Wood and the garden. Unsurprisingly with feeder-based ringing, Tits dominated the catch with Blue and Great Tits making up 49% of the total birds ringed. However, we also had good returns of finch species, particularly Greenfinch with 167 ringedInevitably with feeder ringing, you also accumulate a lot of reencountered birds and with these subsequent encounters included it brought our total encounters for the year up to 3,509 and supplies us with great ongoing data on survival in the population. Despite this large number of reencounters, the majority of our birds are still yet to be subsequently encountered.

Table: Birds ringed in Charter wood 31/03/2019-30/03/2020.
Blue Tit
Great Tit
Long-tailed Tit
Collared Dove
Coal Tit
Great Spotted Woodpecker
Reed Bunting
Song Thrush
Green Woodpecker



  • I estimated a loose winter flock of ~250 Greenfinch were present in the wood this year, an excellent number for this species that was so badly hit by trichomonas. This is potentially an underestimate, as catching two-thirds of the flock would be a pretty good rate.      

  • Chaffinch numbers would be higher, but the local population is suffering from papillomavirus and as such those birds are released unringed.
  • A couple of Brambling were great additions during early winter and two more individuals were ringed during spring passage. I assumed the Autumn birds were just passage, but a retrap of the female 17 days later indicated she was perhaps just being inconspicuous.
  • 26 Collared Doves ringed won’t excite many ringers, but by 2018 numbers this is 50% of the county total.

  • 15 Jays ringed on the other hand did feel special for a single site in a short-ish period, so we started a colour ringing project on them in January 2020. We’ve only fitted 2 colour rings so far, but we are expecting/hoping captures will increase later in the season.

  • No feeding station would be complete without a Sparrowhawk or two eking out a living. We’ve had at least two individuals this year, with both a male and female finding their way into a mist net. Sadly, the male was found dead after entering a man-made structure locally just 22 days later.

  • Controls and recoveries have been pretty quiet for this site sadly. What movements we have had have only been local movements of Tits. We are still waiting to hear back about a Blue Tit ringed back in 2014 though, so hopefully that will be more exciting.
  • 9 ringed birds have subsequently been found deceased, in all cases unrelated to the ringing event. 5 of these were a result of predation from domestic cats, a Sparrowhawk died after entering a man-made structure, and 3 birds succumbed to natural causes.

Heard often in Charter Wood but rarely ringed, just six Bullfinch over the year.

Heard even more than Bullfinches, but seldom caught. This adult female is one of at least five Green Woodpeckers in Charter Wood. You can see the sticky saliva in her bill that helps them catch ants and other invertebrates.

Charter Wood doesn't attract many Goldcrests, only 8 were ringed across the year.

One of the two Treecreepers ringed.

Plenty of Woodpigeons in Charter Wood, only a tiny proportion were ringed.

The very first bird ringed; a Great Tit sporting a completely white outer tail feather.


Bordering the northern edge of Charter Wood is a 50-acre arable field that was left as stubble this winter. Skylarks breed here on the neighbouring horse pasture so I suspected we may also have a wintering population that we could try and monitor. Being inside a city doesn’t really lend itself to dazzling (catching birds by torch and hand net), our light pollution to put it simply is pretty horrendous and for dazzling you want it dark. The saving grace was a thermal imager, lent to us by group leader Iain Barr. With the imager we can find birds more efficiently and ensure a better approach for catching; combining this with choosing the best conditions to reduce light pollution really helped our success rate. We didn’t have access to the imager for most of the winter but in February and March we had a chance to put some time into monitoring the birds using the stubble field during winter. It was also a great opportunity for me to teach a few group members that have not experienced much of the technique and I usually had a group with me in tow. To our surprise we stumbled across a particularly good population of Woodcock (in Norwich terms) with counts as high as 15 our best. We were delighted to ring 9 Woodcock, especially considering only 9 were ringed in the entirety of Norfolk in 2018! Counts of Skylark roosting in the field peaked at ~10-15 on a single night, with at least three singing males during the day that I can currently hear singing high above the house as I type. We managed to ring 15 Skylark, a species rarely caught by conventional methods which is reflected in the fact that only 2 adults were ringed in the whole of Norfolk in 2018.  We also recorded several pairs of Red-Legged Partridge, as well as sparse encounters with Lapwing, Stock Dove, Little Owl, Redwing, and Fieldfare. This was only with a handful of visits though, so we are excited to get back out monitoring next winter.

Ringing totals:
Stock Dove

I had peak counts of 8 Stock Dove on the farm during the day mixed in with the more common Woodpigeons, but we didn't come across many roosting at night.

No day time records of Lapwing on the farm, so to record an individual present at night was a treat.

One of the many Woodcock using the farm to feed at night, and the view through the thermal imager as I approached it.

Charter Wood nest box scheme

As part of ongoing monitoring of the wood we embarked on establishing a nest box scheme in early 2020. With a grant from UEARG to supply the wood we built 56 hole-fronted nest boxes and 5 open-fronted nest boxes that have gone up throughout the wood. We have also put up raptor boxes with one of each KestrelTawny Owl, and Little Owl box going up. With this and a large chunk of nest finding, we can now hopefully start monitoring the breeding success of some of the wood’s inhabitants. Unfortunately, a well-meaning member of the public has recently also put up roughly 20 boxes through the woodland (without permission) and these boxes are sealed shut so will not be able to be monitored.

One of the many passerine nest boxes.

Tawny Owl Nest Box. Both Male and Female calls have been heard in Charter Wood through early spring.

Graphs of Charter Wood ringing

Captures by month
Total monthly captures unsurprisingly peaked in late autumn/winter months, with the busiest month being October. Supplementary feeding was provided to a far greater extent in winter and winter is generally the time when bird numbers at the feeders peak.

Captures by month corrected
Correcting for the amount of trapping effort each month isn’t very easy when you operate varying trapping methods (some of which are passive such as maze traps). A very rough way of correcting for effort is to simply calculate number of birds caught per trapping day (where a trapping day is considered a day where at least one individual was trapped). Here we see peak captures occurring in November rather than October.

Species richness by month
The number of species caught each month was fairly stable but this month was our best with 21 different species ringed.

Top 6 species by month
Here is the monthly captures for the most frequently caught species, corrected by number of trapping days in that month.

Capture number histogram
Most birds (57%) have only ever been encountered once, but a small proportion can be described as ‘trap happy’ and end up making up a surprising proportion of our large number of retraps (just 26 individuals make up almost 20% retraps). These are mostly Great Tits, Dunnocks, and Robins that become accustomed to potter traps and perhaps considered the free meal a worthwhile trade for the data I wanted from them.