Seagulls actively forage and socialize during daylight hours. Their constant presence in coastal and urban environments often sparks curiosity about their activities once darkness falls. While their daytime behaviors are well-known, their nocturnal habits, including where they go and how they rest, are less frequently considered. This shift highlights their adaptability, moving from bustling daytime routines to more secluded nighttime behaviors.
Nighttime Roosting Locations
As night approaches, seagulls seek specific roosting locations, prioritizing safety and proximity to food sources. Many gather in large communal roosts, often on open water bodies like oceans, lakes, and reservoirs. Sleeping on water provides a natural barrier against most land predators. Beaches and sandbars are also common choices, offering open views of approaching threats.
Secluded islands and coastal cliffs provide elevated, isolated spots for nighttime rest. In urban areas, seagulls adapt by using rooftops, buildings, piers, and jetties, which offer height and protection from ground predators. These structures provide a vantage point even while resting. Their selection of diverse sites demonstrates versatility in finding secure places to conserve energy until dawn.
Activity and Sleep Patterns
Once at their roosting sites, seagulls exhibit reduced activity compared to their busy daytime routines. While primarily diurnal, they engage in sleep with unique physiological adaptations. Like many bird species, seagulls utilize unihemispheric slow-wave sleep (USWS), where one half of their brain rests while the other remains partially alert. This allows them to keep one eye open, maintaining vigilance for potential dangers even while sleeping.
This ability to rest one brain hemisphere helps them remain aware of surroundings, enabling quick reactions to threats. They can switch between unihemispheric and bihemispheric (both brain halves resting) sleep depending on perceived safety. During nighttime rest, minimal movements, such as shifting positions or occasional vocalizations, might occur, but overall activity is low. Their sleep duration ranges from five to eight hours, often broken into shorter bouts throughout the night.
Perception and Protection in Darkness
Seagulls navigate and protect themselves in low light using sensory capabilities and collective behaviors. Although predominantly active during the day, their vision adapts for dim light. Their eyes contain specialized oil droplets in cone cells, which enhance their ability to see colors and improve vision in hazy conditions, including twilight. However, they lack the specialized night vision of truly nocturnal birds like owls, which have a high density of rod cells and a reflective layer in their eyes.
To compensate for limited night vision, seagulls rely on other senses, such as hearing, to detect movements or sounds indicating a threat. Their collective roosting behavior is a significant safety mechanism, as large groups offer safety in numbers. Within these groups, individuals may take turns being vigilant, with some remaining alert while others sleep. Choosing secure locations like open water, high cliffs, or urban rooftops further enhances their protection from nocturnal predators.