The Larus ridibundus, commonly known as black-headed gull, is a small to medium-sized gull widely distributed across Europe, Asia, and coastal regions of North Africa. Despite its name, the adult's head is not truly black but dark chocolate-brown during breeding season. It is a familiar sight in inland lakes, rivers, farmlands, and even urban areas.
Scientific Classification
Morphology and Distinctive Features
Size: Length 34–37 cm, wingspan 94–105 cm, weight around 200–400 g.
Plumage:
Breeding season: Distinctive chocolate-brown head, white body, grey wings with black-tipped primaries.
Non-breeding season: Head turns mostly white with a dark ear spot.
Bill and legs: Reddish in adults.
Eyes: Pale with a red orbital ring.
Call: A sharp, laughing “kree-ar” or “rreeeh,” which gave rise to the name ridibundus (Latin for “laughing”).
Distribution and Habitat
The black-headed gull breeds across most of Europe, Central Asia, and parts of North Africa, and migrates southwards in winter to coasts and inland water bodies.
Preferred habitats:
Lakes, marshes, riverbanks, estuaries.
Agricultural fields and garbage dumps.
Urban parks, harbors, and sewage works.
It is highly adaptable and has become increasingly common in urban environments.
Behavior and Life Cycle
Diet:
Omnivorous and opportunistic. Feeds on insects, worms, small fish, invertebrates, scraps, grains, and even human food waste.
Often follows ploughs in fields and flocks with other gulls near water or dumpsites.
Breeding:
Colonial nester, often in large, noisy groups.
Builds nests on the ground using vegetation, often on islands or marshy areas.
Lays 2–3 eggs; both parents share incubation (about 23–26 days).
Chicks are semi-precocial and fledge around 5–6 weeks after hatching.
Migration:
Northern populations are migratory, wintering in southern Europe, North Africa, the Middle East, and India.
In milder regions, it can be sedentary or partially migratory.
Ecological Adaptations
Generalist feeder: Adapts its diet to available resources, which contributes to its success in a wide range of habitats.
Social behavior: Highly gregarious, especially during breeding and migration, which offers protection and increases foraging efficiency.
Flight: Agile flier, capable of catching insects mid-air and performing tight maneuvers over water.
Conservation
IUCN Status: Least Concern (LC) – Populations are stable or increasing in many regions.
Threats:
Disturbance of breeding colonies by humans or predators.
Habitat loss due to wetland drainage or development.
Pollution and ingestion of plastics.
Protection measures: In many countries, breeding colonies are protected by law, especially within wetlands of international importance (e.g., Ramsar sites).
Curiosities
Despite its name, the black-headed gull never has a truly black head—it's actually a rich chocolate brown.
It is often seen in mixed-species flocks, sometimes stealing food from other birds (kleptoparasitism).
It is one of the most widespread and abundant gulls in Europe, often acting as a biological indicator of environmental changes.
Known to display complex social behaviors, including aerial courtship displays and communal chick crèches.
Role in the Ecosystem
Scavenger: Helps control waste and carrion in both natural and urban environments.
Pest control: Eats large quantities of insects and larvae, benefiting agriculture.
Prey species: Eggs and chicks are preyed on by foxes, corvids, and larger birds of prey.
Bioindicator: Its presence and behavior can reflect the health of aquatic and agricultural ecosystems.
References__________________________________________________________________________
Arnal A, Vittecoq M, Pearce-Duvet J, Gauthier-Clerc M, Boulinier T, Jourdain E. Laridae: A neglected reservoir that could play a major role in avian influenza virus epidemiological dynamics. Crit Rev Microbiol. 2015;41(4):508-19. doi: 10.3109/1040841X.2013.870967.
Abstract. Avian influenza viruses (AIVs) are of great concern worldwide due to their economic impact and the threat they represent to human health. As wild birds are the natural reservoirs of AIVs, understanding AIV dynamics in different avian taxa is essential for deciphering the epidemiological links between wildlife, poultry and humans. To date, only the Anatidae (ducks, geese and swans) have been widely studied. Here, we aim to shed light on the current state of knowledge on AIVs in Laridae (gulls, terns and kittiwakes) versus that in Anatidae by setting forth four fundamental questions: how, when, where and to which host species are AIVs transmitted? First, we describe ecological differences between Laridae and Anatidae and discuss how they may explain observed contrasts in preferential transmission routes and the evolution of specific AIV subtypes. Second, we highlight the dissimilarities in the temporal patterns of AIV shedding between Laridae and Anatidae and address the role that immunity likely plays in shaping these patterns. Third, we underscore that Laridae may be key in promoting intercontinental exchanges of AIVs. Finally, we emphasize the crucial epidemiological position that Laridae occupy between wildlife, domestic birds and humans.
Yang C, Wang QX, Huang Y, Xiao H. Analysis of the complete mitochondrial genome sequence of Larus brunnicephalus (Aves, Laridae). Yi Chuan. 2012 Nov;34(11):1434-46. Chinese. doi: 10.3724/sp.j.1005.2012.01434.
Abstract. The complete sequence of mitochondrial genome of Larus brunnicephalus was determined using long PCR and conserved primers walking approaches. The results showed that the entire mitochondrial genome of L. brunnicephalus is 16,769 bp in length, which has been deposited in GenBank with the accession number JX155863. The mitochondrial genomic organization and gene order of L. brunnicephalus were consistent with that of Gallus gallus, which contains 13 protein coding genes (PCGs), 22 tRNA, 2 rRNA, and a control region. Except for COI gene using GTG and ND3 gene with ATT as the initiation codon, all other 11 PCGs of the mtDNA in L. brunnicephalus started with the typical ATG codon. AGG, TAG, TAA, or AGA were used in 11 PCGs as usual termination codons, except for COIII and ND4 genes with incomplete termination codon (T). The secondary structures of 22 tRNAs were predicted and it is found that the tRNASer (AGN) lacks DHU arm and tRNAPhe contains the fourth types of permutation in the TψC arm. It is predicted that the secondary structures of 12S rRNA and 16S rRNA include 4 structural domains with 47 helics and 6 domains with 60 helics, respectively. F-box, E-box, D-box, C-box, B-box, Bird similarity-box, and CSB-boxes (1-3), which were found in the control regions of other bird species were also present in L. brunnicephalus. The sequence in the starting regions of H-strand replication (OH) and the bidirectional light and heavy-strand transcription promoters (LSP/HSP) in the control region were also predicted. Result of phylogeny analysis supports that L. brunnicephalus should be categorized into the Masked gulls species.
Ushine N, Kurata O, Tanaka Y, Sato T, Kurahashi Y, Hayama SI. The effects of migration on the immunity of Black-Headed Gulls (Chroicocephalus ridibundus: Laridae). J Vet Med Sci. 2020 Nov 12;82(11):1619-1626. doi: 10.1292/jvms.20-0339.
Abstract. In order to elucidate the relationship between migration period and immunity related to susceptibility, we conducted research on Black-headed gulls (Chroicocephalus ridibundus). We captured 260 gulls and collected their peripheral blood. Their leukocyte (WBC) count, percentages of heterophils (Het) and lymphocytes (Lym), heterophil and lymphocyte ratio (H/L ratio), and CD4 and CD8α expression levels (CD4 and CD8α, respectively) were quantitatively analyzed over three migration periods (Autumn migration, Wintering, Spring migration). In Adult gulls, WBC counts and CD4 levels significantly increased. Moreover, the Het and H/L ratio decreased from the Autumn migration to Wintering. Conversely, only WBC counts and CD4 levels measurements significantly decreased from Wintering to Spring migration (P<0.05). The tested parameters of the Tokyo-bay population show a greater significant difference than the measurements of immunity of the Mikawa-bay population. This study suggests that the migratory period has a negative effect on an aspect of the immune system. Including the period-difference in the immune systems in the local population, it is necessary to investigate the relationship between the ecology of migratory birds and their immunity.
Schwartz T, Besnard A, Pin C, Scher O, Blanchon T, Béchet A, Sadoul N. Efficacy of created and restored nesting sites for the conservation of colonial Laridae in the South of France. Conserv Biol. 2023 Apr;37(2):e14005. doi: 10.1111/cobi.14005.
