Larus cachinnans in Poland

(last update: August 01, 2021)

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cachinnans in Poland

National distribution

Zastów Karczmiski
Kępa Nadbrzeska
Jeziórko
Jankowice
Mietków Reservoir & Chwałów
Kozielno & Topola Reservoir
Mokrzec
Wytyckie Lake
Dankowice / Foskowiec Pond
Czorsztyn Reservoir
Kuźnica Warężyńska / Pogoria
Dwory

small colonies or single sites

Caspian Gull cachinnans: Włocławek

Breeding species:

• Larus cachinnans
• Larus argentatus

Habitat: 

Breakwater on Vistula river and also roof-top of hall. Some pictues HERE.

Annual numbers:

[from: Breeding large gulls in Poland: distribution, numbers, trends and hybridisation. BY: Neubauer, etall. IN: Vogelwelt 2006-127: 11-22].

At Wloclawek Reservoir, the population structure (based on 177 trapped birds in 2002-04) shows strong dominance of Herring Gull (126 individuals, 71%), followed by Caspian Gull (27 individuals, 15%) and hybrids (19 individuals, 11%), a single Yellow-legged Gull female and four unidentified birds (Fig. 3). Most of 19 birds classified as hybrids (16 individuals) showed characters intermediate between Herring Gull and Caspian Gull (Photo 3-4), and we suppose they were F1 hybrids. Six of them were ringed as chicks in Wloclawek colony during 1992-99 (1992: 1, 1993: 1, 1994: 2, 1999: 2), except for one bird that originated from the middle Vistula (ringed 1995 as a chick near Tyrzyn Dworski, 51°39’N, 21°38’E). Another two putative hybrids showed a mixture of characters of all three species (newly ringed 2003-04 as adults in Wloclawek) and one was clearly intermediate between Caspian Gull and Yellow-legged Gull (ringed as a chick in Wloclawek in 1995, Photos 5-6). Assuming that these birds are F1 hybrids (which seems probable as intermediacy is most likely to be detected in the F1 generation), this would indicate that hybridisation occurred in the colony at least since 1992. At Wloclawek Reservoir mixed pairs comprised about half of the breeding pairs sampled (samples averaged c. 33% of all pairs) during 2002-04. Moreover, about half of all mixed pairs in each season were comprised of two pure species - Herring Gull x Caspian Gull. Other mixed pairs included hybrids paired with pure birds or two paired hybrids. With four species categories distinguished (argentatus, cachinnans, michahellis and hybrids), mating in Wloclawek was not significantly different from that expected if taxa do pair at random (G-test: G2 = 7.11, df = 6, exact P = 0.43). Interestingly, however, in the 15 pairs of pure Herring Gull mated with other species or hybrids, 11 cases involved a male Caspian Gull or hybrid paired with a Herring Gull female while in only four cases a Herring Gull male was paired with a female of either Caspian Gull, Yellow-legged Gull or hybrid.

Notes on breeding pairs:

In breeding season 2020, xx hybrid pairs and xx pure pairs of Larus michahellis, etc etc.

Ringing team for this location:

• ringer Łukasz Bednarz
• Person Y

Ring readings from this location:

Bulk of the birds were recorded in country XX and country YY, illustrating a westwards migration after breeding.

Remarkable recoveries:

• bird Pxxx, ringed in year XX, and observed in country WW (23.000 km west).
• bird Pxxx, etc, etc
• bird Pxxx, ringed as pullus in Mietków (year 20xx), is now a breeding adult in colony ZZ (eastern Germany / the Netherlands).