Sergey Dereliev

The species occupies various types of open coastal and inland water-fringed habitats, breeding on bare or sparsely vegetated beaches and dunes, islands, banks, flats, salt-marshes, saltpans etc (Molina et al. 2020). Globally distributed across the middle latitudes of all continents. Apart from a small population by the North Sea, most European populations are located in the Mediterranean/ Black Sea region and SW Russia. European strongholds are in Spain & Ukraine (Keller et al. 2020).

Eurasian-African/Asian migrant. European populations winter largely in Africa.

Its population trend in Europe is increasing. Evaluated as “Least Concern” (BirdLife International 2021).

Season of assessment

B

Population trendStable
Population size
(min-max, best estimate)		26700-37400,30900
Red List categoryLC
Franks, S., Fiedler, W., Arizaga, J., Jiguet, F., Nikolov, B., van der Jeugd, Ambrosini, R, Aizpurua, O., Bairlein, F., Clark, J., Fattorini, N, Hammond, M., Higgins, D, Levering, H., Skellorn, W., Spina, F, Thorup, K. Walker, J., Woodward, I. and Baillie, S.R. (1) (2022) Online Atlas of the movements of European bird populations. https://migrationatlas.org EURING/CMS (1) Principal investigator
Map

Overall Connectivity for Gull-billed Tern

Birds from the population around North Sea are encountered mostly along the coastline of W Europe & W Mediterranean, but some are taking S (C & SC Europe) or even SE routes (Poland). Some long-distance recoveries have been obtained in the past (mostly 1920-30s) from the currently reduced Danish population – W Africa (Mauritania, Guinea) and even the Caribbean region (Barbados, possibly a bird blown away from its normal route to W Africa) (Bønløkke et al. 2006).

SW European breeders are encountered in NW Africa during migration and in W Africa (from Senegal to Sierra Leone) and W Sahel (Mali) while wintering. At least some of the birds from the Black & Aegean Sea breeding populations are taking SW & W routes, juveniles from Ukraine and Greece are encountered in Italy (Spina, Volponi, 2008); others are recorded W to Spain and S to W Africa (Ilichev, Zubakin, 1988).

Recoveries by Condition for Gull-billed Tern

Unlike many other species, ringing started early in the 20th century, in late 1920s. Since then, the numbers of encounters fluctuated, the largest “wave” started after 2000. Most encounters are obtained during the breeding season, peaking in Jun-Aug (78% in total). The bulk of encounters come from SW, N & W Europe holding 34, 24 & 15% respectively. The encounters based on dead birds decreased over time: from 90% pre-1960 to 39% after 1991; those based on alive birds considerably increased from 7% before 1960 to 60% after 1991. The latter is mostly due to ringing recoveries, and especially to colour ring resightings; nowadays about 4% of the resightings come from metal ring readings in the field. Shooting as а factor has been reduced from 42% pre-1960 to ca. 1% after 1991.

Annual Movements for Gull-billed Tern

Juveniles from the small breeding population around the North Sea (Germany, Denmark) disperse mainly SW, with encounters as early as Aug in W Europe and the W Mediterranean. Autumn migration is more prominent in Sep. Encounters from W Africa exist from Nov-Feb. Most spring records (Apr-May) are from Italy. The abnormal vagrancy to Barbados has been recorded in late Sep.

Similarly, post-breeding dispersal in the Iberian Peninsula breeders starts in Aug (encounters locally or in NW Africa); wintering records exist from in W Africa (Dec-Feb) & NW Africa (Feb), and return movements in Mar (Algeria).

Birds breeding in the N Black Sea region are encountered in Aug in Romania and some of them reach Spain in early Sep (Ilichev, Zubakin, 1988). Spring migration takes place mainly in Apr.

Connectivity by Month by Region for Gull-billed Tern

Dispersal movements after the breeding season start in late summer, migratory movements being more evident in early autumn. By early or mid-autumn most North Sea region breeders have already dispersed in W Europe and W Mediterranean. Encounters from the wintering grounds in W Africa of both W & SW European breeding populations exist between late autumn and late winter. Danish birds – during their first three years, roam away from their natal colonies, mostly in S Europe (Bønløkke et al. 2006).

N Black Sea region breeders are encountered wintering in W Africa (Senegal, Mali), as well as Caucasian Black Sea Coast (Ilichev, Zubakin, 1988). In general, the species is rarely encountered in winter in S Europe. Return migration is mostly in mid-spring.

Long-distance recoveries connecting SE Europe with African wintering grounds are scarce.

Boris Nikolov

References

Statistics Map
N records N individuals N recoveries
Mapped data*
Total available data
*Mapped data include only distant (>= 50 km) recoveries
References Map
1988 . The Birds of USSR. Vol. 3 – Laridae. Nauka, MoscowEditor(s): Ilichev, V. D., Zubakin, V. A.
2020 . European Breeding Bird Atlas 2: Distribution, Abundance and Change. European Bird Census Council & Lynx Edicions, BarcelonaEditor(s): Keller, V., S. Herrando, P. Voříšek, et al.
BirdLife International 2021 . Species factsheet: Gelochelidon nilotica. Downloaded from http://www.birdlife.org on 20/09/2021.
Bønløkke, J., Madsen, J. J., Thorup, K., Pedersen, K. T., Bjerrum, M., Rahbek, C.2006 . Dansk Traefugleatlas. Rhodos, Humblebæk
Molina, K. C., J. F. Parnell, R. M. Erwin, J. del Hoyo, N. Collar, G. M. Kirwan, and E. F. J. Garcia 2020 . Gull-billed Tern (Gelochelidon nilotica), version 1.0. Link to Article (DOI: https://doi.org/10.2173/bow.gubter1.01)
Spina, F., Volponi, S. 2008 . Atlante della Migrazione degli Uccelli in Italia. 2. Passeriformi. Ministero dell’Ambiente e della Tutela del Territorio e del Mare, Instituto Superiore per la Protezione e la Ricerca Ambientale (ISPRA), Tipografia SCR-Roma

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