The Laridae family, commonly known as gulls, is a diverse group of birds belonging to the order Charadriiformes, comprising over 50 species distributed across the world, particularly in coastal regions. Gulls are highly adaptable birds, found in a wide range of environments from oceanic shores to inland habitats. Known for their opportunistic feeding behavior, gulls have become one of the most recognizable and widespread bird families, often associated with coastal areas and urban environments.

Scientific Classification

• King: Animalia

• Phylum: Chordata

• Class: Aves

• Order: Charadriiformes

• Family: Laridae

Morphological Characteristics

Gulls are medium to large-sized birds characterized by their robust bodies, long wings, and relatively long legs. They have a strong, straight beak that is slightly hooked at the tip, adapted for scavenging and eating a wide range of food, including fish, insects, and human food waste. The plumage of gulls is typically a mix of white, gray, and black, with some species displaying more striking color patterns. Their long wings enable them to glide effortlessly over the water, while their webbed feet make them agile swimmers.

The bill shape can vary across species, with some having a more pointed bill suited for picking insects, while others have broader bills adapted for scavenging fish. Gulls are also known for their large, expressive eyes, which allow them to locate food from a distance.

Behavior and Feeding Habits

Gulls are primarily opportunistic feeders, taking advantage of a variety of food sources depending on availability. They are known to scavenge human food waste, particularly in urban areas, and can be seen around docks, beaches, and garbage dumps. They also catch fish, small marine invertebrates, and occasionally insects and other animals. Gulls may forage by diving into the water, flying over the surface in search of prey, or scavenging from other animals or human activities.

Their adaptability is reflected in their diverse feeding habits, and some gull species are known to engage in kleptoparasitism, stealing food from other birds or even from humans. They are also known to be territorial during breeding seasons, especially around nesting sites.

Habitat and Distribution

Gulls are widely distributed and are typically associated with coastal habitats, including beaches, cliffs, and estuaries, but they can also be found in inland areas, particularly around lakes, rivers, and garbage dumps. They are migratory birds, with some species traveling long distances to breed or find food, while others remain in coastal regions year-round. Many gull species have adapted to urban environments, where they scavenge in city parks, waste disposal sites, and near human settlements.

Reproduction

Gulls are known for their colonial nesting behavior, often forming large colonies on coastal cliffs, islands, or in urban environments. Their nests are typically built on the ground or in shallow depressions and are made from a variety of materials, including grass, twigs, and feathers. Female gulls usually lay 2-3 eggs, and both parents take turns incubating the eggs. After hatching, both parents are involved in feeding and protecting the chicks until they are old enough to fend for themselves.

The parental care exhibited by gulls is remarkable, with both the male and female actively involved in chick rearing. In some species, adult gulls will provide food by regurgitating it for their young, ensuring that they are nourished during their early stages of development.

Conservation

While many gull species are abundant and widespread, some have seen population declines due to habitat loss, pollution, and human encroachment. Coastal development and the degradation of breeding habitats can affect gull populations, particularly in areas where urbanization has led to the destruction of natural nesting sites. However, some species have adapted well to human presence and have flourished in urban environments.

Gulls are also affected by pollution, particularly marine pollution, as they can ingest plastic waste or become entangled in discarded fishing gear. Conservation efforts are focused on protecting coastal habitats and reducing pollution to ensure the health of gull populations.

Conclusion

The Laridae family represents a highly adaptable group of birds that have successfully established themselves in diverse environments around the world. Gulls are vital components of coastal and urban ecosystems, playing roles as scavengers, predators, and even as indicators of environmental health. Their opportunistic feeding habits and striking appearance make them one of the most familiar bird families. Despite some challenges related to habitat loss and pollution, many gull species continue to thrive, demonstrating their resilience and adaptability in a rapidly changing world.

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.