This is an egg of the Slender-billed Gull (Chroicocephalus genei), a medium-sized gull belonging to the family Laridae (gulls).

Slender-billed Gull eggs are typically oval to sub-pyriform (slightly pear-shaped), measuring approximately 5.3–5.9 cm in length and 3.6–4.0 cm in breadth. The ground colour ranges from pale buff or greenish to light brown, marked with darker brown, grey or black blotches and spots, providing camouflage in open nesting habitats.

Location:
Slender-billed Gulls breed in coastal and inland saline environments across the Mediterranean, Black Sea and Caspian regions, extending into parts of southern Europe, North Africa and western to central Asia. They nest in colonies on sandy shores, saltmarshes, lagoons and saltpans. Outside the breeding season, many populations disperse along coasts and estuaries.

Average Size:
Length: ~5.3–5.9 cm.

Breadth: ~3.6–4.0 cm.

Family:
Laridae (gulls)

Species:
Chroicocephalus genei

Ecological Role:
Slender-billed Gulls feed mainly on small fish, crustaceans and other marine invertebrates, typically foraging in shallow saline waters. They play a role in regulating invertebrate populations and contribute nutrients to coastal and wetland ecosystems through their colonies.

Movement and Behaviour:
This species is partially migratory, with many populations dispersing or moving southwards after breeding. It is strongly associated with lagoons and coastal wetlands, often feeding by picking prey from the surface or in shallow water using sweeping or probing movements.

Reproduction & Eggs:
Nests are shallow scrapes on sand, mud or low vegetation, often in dense colonies. A typical clutch consists of 2–3 eggs. Both parents share incubation, which lasts approximately 23–26 days. Chicks hatch down-covered and mobile (precocial), remaining close to the nest site but dependent on parental care. They typically fledge after approximately 3–4 weeks.

Conservation Status:
Globally assessed as Least Concern by the International Union for Conservation of Nature (IUCN), although local populations may be affected by habitat loss, disturbance and changes in wetland environments.

Collection Date:
Collected on the 14th of May 1882.