BLE Seabird Resource Hub - Science of Seabirds
The biology of seabirds
Seabirds are widely distributed around the globe from pole to pole. Some spend their whole lives in the open ocean, only coming to land to breed and nest, while others occupy coastlines and habitats near the shore all year round.
Seabirds are a very diverse group and exhibit striking evolutionary adaptations. All seabirds have pronounced salt glands near the base of their bills which pumps salt out of the bloodstream more efficiently than the kidneys. They lead very “slow” lifestyles, in the sense that they grow more slowly and live longer than land birds, and raise only one or two chicks per year.
Some seabirds, such as petrels, have enhanced sense of smell capabilities, something very uncommon in most other bird groups, allowing them to locate their food easier. Others, such as the Arctic Tern, can make annual trans-equatorial migrations involving tens of thousands of kilometers.
They have phenomenal swimming capabilities, where some are able to dive up to 200 meters to catch fish, that's longer than the Ulm Minster in Ulm Germany, the Mole Antonelliana in Turin Italy, or the Gateway Arch in St Louis USA.
How to study seabirds
Most observations of seabirds take place at their colonies when they nest and form the foundation of what we know about seabird biology. They provide fundamental answers about breeding, how many chicks a parent will produce and hard the parent has to work to raise those chicks.
Since seabirds take their food from the seas, understanding what seabirds do at sea is also important; otherwise we wouldn’t completely understand their biology. Seabird surveys at sea (i.e. pelagic surveys which refers to non-coastal parts of the ocean) are common practice to have an understanding of birds at sea. The most common method is by sampling parts of the water from a boat which would represent an appropriate sample of the area we would want to study. Observers note down all the seabirds seen within a predetermined ‘strip’. Records of fish densities can also be taken using hydroacoustics.
More recently, seabird tracking has been a game changing technology in understanding seabird biology. For decades, people have wondered where seabirds are going to and coming from when they disappear from land. Recent severe declines and clues that the declines are related to a lack of safe and plentiful feeding opportunities have meant that scientists have turned to technology to help solve these mysteries. Seabird tracking can reveal feeding hotspots, overlap with offshore development and areas where seabirds are at greatest risk of interacting with fisheries.
The new information from these surveys and tracking allows us to learn more about where and when seabirds concentrate at sea, and how that relates to under the sea. Oceanographic sampling and satellite images of the ocean’s surface are also other methods of studying seabirds at sea. Other factors such as the sea temperature, sea salinity, and ocean features are also important records.