This period, the juveniles from the various seabird species of Madeira are leaving their burrow to start their adventures in the open ocean. The fledglings are motivated to go out of their burrow because their parents have left them and they have to provide for themselves now, without any help or guidance form the parents, otherwise they will starve. Driven by this motivation and instinct, the fledgling goes out of the burrow for the first time. Finding the sea quickly is very important for the fledglings, as being out of their burrow on land makes them more vulnerable for predators. The next step is to find a point from where the bird can take off for the first flight. They sometimes have to walk/wobble to find a good spot or they will use their beak and legs to climb to a higher point. Now, they can finally try out their wings and get some food.
In a perfect world, the seabirds would be able to find their way to the ocean with relative ease. Nowadays, it's a different story, as seabirds can easily get distracted by the high levels of artificial lights coming from cities and streetlights etc. They might fly in the wrong direction, towards a city instead of the coast for example, and get crashed with infrastructures or they might get grounded on a road and get hit by a car. The disorientation might also cause death from exhaustion as the bird gets lost from the initial route and keeps circling around the same source of light. So artificial light is a major problem for the seabirds here on Madeira and all over the world. But why exactly do seabirds react to artificial light at night (ALAN)? The following reasons might give some explanation:
One of the reasons why seabirds are attracted by artificial light is because they associate the light with a source of food. Many seabirds eat seafood with bioluminescent properties. An experienced bird might be better at telling apart their bioluminescent prey from an artificial light source, but young fledglings are inexperienced and there is no-one to teach them so they are more likely to get confused.
The second explanation is also related to food. Before going out of the burrow, all the chick has ever seen was basically nothing, as they grew up in a dark hole (but this also depends on the depth and other characteristics of the burrow, as some are darker than others). But there was likely some light coming into the burrow form the entrance and this was also were their parents can in to give the chick food. Thus, it could be that chicks associate light with getting food, as the food was always coming from the lighter burrow entrance. Or they just really miss their parents.
Lastly, artificial lights block out ambient lights coming form the moon and stars, which the birds naturally use for navigation. Studies have found that on dark nights, more birds get fledged than on nights with a full(er) moon. This is because on full moon night, the intensity of artificial lights is less relative to the light coming from the moon so the pulling effect of the moon is stronger compared to other nights where the light is predominantly coming form artificial light sources.