Publications
Colour rings
	NIOZ programme
	RIN programme

 

Colour rings on both legs with 1-letter or inscription other on tarsus, no metal ring

 

Report to: kees.camphuysen@nioz.nl or kees.camphuysen@wxs.nl

B		H		Z		A
YBGH				OZZA

 

       

            GYZ2  (LBBG)                                                             GPZ2  (YLG)

            (© Antonio Gutierrez)                                            (© Bennie Middendorp)

 

The RIN – Herring Gull ringing programme 1986-1988

In the mid-1980s, Arie L. Spaans, at the time working at the Rijksinstituut voor Natuurbeheer (RIN) in Arnhem, announced that in 12 Dutch Herring Gull colonies, fledglings would be colour ringed with large, conspicuous rings on both legs. The ringing was scheduled for 1986-1990 and some 1250 gulls would be marked per annum (100 per annum in each of the participating colonies). Aim of this project was to study dispersal, annual survival, and recruitment of Herring Gulls in the Netherlands during a period of rapid population growth.

The rings used were large and conspicuous and colours deployed included blue (B), green (G), orange (O), white (W), yellow (Y), and black (Z) [note that the capital letters indicate the annotation used when these rings are archived or reported, esp. the use of B for Blue and Z (= Dutch zwart) for Black is perhaps confusing].

The inscription is a single letter, a figure or one, two or three parallel bars.

Letters used	A	B	C	D	E	G	H	J	K
	L	N	P	S	T	X	Y	Z
Figures used	1	2	4	6	7	9
Bars used	-	=	≡

 

The inscription is repeated 3 times so that a ring can be read from all angles of observation; the bars run around the ring (horizontally). For notation, the protocol suggests to mention the left ring first, followed by the right ring, and to use B for blue and Z for black. Furthermore, it was suggested to write — for single bar, F for double bar and 3 for triple bar inscriptions.

Examples:

            ZFW—             Left Black double bar, right White single bar

            B4GG               Left Blue 4, right Green G

            YYW3              Left Yellow Y, right White triple bar

 

The chicks were not ringed with a metal ring (although some have been recaptured and were ringed in later years). As a result, loss of one of the rings does pose serious problems and many ‘single ringers’ are now in fact unidentified individuals, even when found dead.

With the retirement of Arie Spaans, some years ago, the database was transferred to NIOZ for further maintenance and updating and the analysis of data is a current activity by Kees Camphuysen, as part of the NIOZ gulls studies. The old database was modernized, transferred into Paradox 8.0, and is combined with the database developed for the NIOZ studies and gull colour ring programme. New sightings are welcomed and processed at NIOZ, and life-histories are provided with return mail, whenever possible (contact kees.camphuysen@nioz.nl)

 

Ringing effort  The systematic ringing effort of RIN was infact reduced to a period of three years (1986-1988), but instead of the initial 12 colonies scheduled to participate, gulls were captured and ringed in up to 14 colonies (Table 1). IJmuiden and Saeftinghe colonies joined in later years, whereas Wassenaar was under predation pressure of Red Foxes to such an extent that in 1988 it was impossible to find sufficient chicks to ring. In all, 4028 Herring Gull chicks were marked. Earlier (13 in Wassenaar in 1985) and later (47 in Europoort in 1991-92 and one at Texel in 1994), small numbers of Herring Gulls were ringed, resulting in a total of 4089 Herring Gulls in the database.

 

Table 1. Herring Gulls colour-ringed between 1986 and 1988 in 14 selected colonies, the number of reports, and the fraction of ringed birds ever reported  per colony.

Colony	1986	1987	1988	Reports	% reported
Rottumeroog	103	103	105	3098	85.2
Rottumerplaat	105	105	100	2306	66.1
Schiermonnikoog	118	108	105	2884	74.6
Ameland	102	105	104	2303	69.1
Terschelling	103	110	115	3970	88.7
Vlieland	105	105	106	5048	91.1
Texel	103	104	105	7409	95.5
Callantsoog	105	104	104	12378	85.6
Schoorl	102	99	103	14264	91.8
IJmuiden	—	—	105	7567	99.0
Wassenaar	105	104	40	3964	59.8
Europoort	104	105	105	8186	87.9
Schouwen	105	105	104	9549	92.0
Saeftinghe	—	105	105	4173	79.5
	1260	1362	1406	87099	82.9

 

Apart from Herring Gulls, whether or not accidentally, 97 Lesser Black-backed Gulls were colour-ringed. In later years, more Lesser Black-backed Gulls were ringed with similar ring-combinations (provided by RIN to some colony workers), such as in IJmuiden (199 by Fred Cottaar and Kees Verbeek, 1992-98), at Europoort (205 by Norman van Swelm, 1990-92) and at Terschelling (13 by D. Bukacinski, 1994), as a result of which the database does contain material for 459 Lesser Black-backed Gulls. Fred Cottaar (14x IJmuiden) and Norman van Swelm (10x Europoort) ringed between 1990 and 1998 also 24 Yellow-legged Gulls Larus michahellis or hybrids between Yellow-legged Gulls and Lesser Black-backed Gulls L. michahellis x fuscus, for which the ringing data are also available in the RIN/NIOZ database.

Ring colour combinations and origin  Colours used for Herring Gulls in the main ringing programme of RIN were blue, green, red or black with white inscriptions, and orange, yellow or white with black inscriptions. Colour combinations were indicative for the colony where the rings were deployed (Table 2). The inscriptions and their frequency of occurrence at left and right Herring Gull  rings are indicated in Table 3.

It is unfortunate that the colours of yellow, orange and white rings were hard to identify in later years: white turned into yellowish, orange turned into yellowish, yellow turned into whitish, and because all these colours have black inscriptions, quite a few ring-readings were wrong. Also, it seemed that especially the lightly coloured rings were more easily lost than darker rings. Now, after more than 20 years since the rings have been deployed, utmost care is needed to correctly identify the colour of the rings seen.

Table 2. Colour combinations for Herring Gulls ringed between 1986 and 1988 (n= 4028) and letters used to indicate colours when sightings are reported and stored into the database: B = blue, G = green, O = orange, R = red, W = white, Y = yellow, Z = black [zwart]

Colony	L	R	1986	1987	1988
Ameland	O	G	102	105	104
Callantsoog	W	Z	105	104	104
Europoort	Y	Y	51	53	53
Europoort	Z	Z	53	52	52
IJmuiden	W	G			105
Rottumeroog	O	W	103	103	105
Rottumerplaat	O	Y	105	105	100
Saeftinghe	B	R		105	105
Schiermonnikoog	O	Z	105	105	105
Schiermonnikoog	R	Y		3
Schiermonnikoog	Y	B	13
Schoorl	W	G	102	99	103
Schouwen	G	G	52	52	51
Schouwen	W	W	53	53	53
Terschelling	W	R		5	10
Terschelling	Y	W	104	105	105
Texel	Y	G	103	104	105
Vlieland	Y	Z	105	105	105
Wassenaar	Z	G	105	104	40

 

Table 3. Inscriptions used, notation, and frequency at left and right legs of Herring Gulls ringed between 1986 and 1988 in The Netherlands.

Left	Notation	Frequency	Right	Notation	Frequency
	.	13		.	3
			–	—	193
=	F	21	=	F	196
≡	3	21	≡	3	198
1	1	206	1	1	199
2	2	210	2	2	135
4	4	21	4	4	200
7	7	21	7	7	197
9	9	21	9	9	195
A	A	299	A	A	166
B	B	297	B	B	173
D	D	278	D	D	175
G	G	279	G	G	178
H	H	277	H	H	183
J	J	289	J	J	185
L	L	289	L	L	190
N	N	287	N	N	196
P	P	281	P	P	200
S	S	253	S	S	202
T	T	230	T	T	202
X	X	228	X	X	201
Y	Y	207	Y	Y	202
			Z	Z	59

 

Ageing gulls and ring wear Gulls tend to grow older than their rings, that is, a maximum age of over 30 year (a realistic age for the very old Herring and Lesser Black-backed Gulls) has thus far not been proven to be possible for colour rings deployed in the 1980s. Nevertheless, there are still intact combinations in the field that have been followed for 22 years so far, indicating that at least in some birds the rings do last very long.

            Unfortunately, since the early days of colour-ringing, it became clear that colours faded and rings were lost, leading to difficulties for readers and database managers alike. Few cases of ‘single-ringers’ can still be followed, simply because local knowledge could provide the necessary data to “prove” the identity of some of these birds. Outside their traditional surroundings, however, these birds are nearly just as anonymous as any unringed bird seen. Given the exceptional site faithfulness of large gulls, however, both while breeding and as migrants and wintering birds, some patterns derived from “single-ringers” can still be linked to the whereabouts of some individual prior to its ring loss. We do recommend that ring-readers report such birds, therefore, even if we will be unable to provide a full life-history. It also learns us quite a bit about the scale of ring loss and perhaps even about the colours of rings most prone to wear and loss.

An extraordinary example of resistence of colour rings: WGWY was ringed 2 July 1987 by Cor Berrevoets at Schouwen and seen again 6 January 2008 at Maasvlakte. After 20.5 years, the colour rings were both still intact and still white! White rings in particular were prone to wear and tear and many were lost after only a few years. (© Tom van Wanum)

Another extraordinary example of resistence of colour rings: ZDGA was ringed in summer 1986 at Wassenaar  and seen repeatedly in July and August 2009 at the fish market in Leiden after 23  years; the colour rings were both still intact and still colourful! (© Maarten van Kleinwee)