Due to their isolation, no land carnivore made it to the islands by their own means, but together with Galapagos hawks, two owl species are found here…
It seems obvious that visitors ask themselves, why are there so few predators in the islands if there’s so much to eat? One reason is for sure isolation since the islands are about 1,000 Km from the near-est point in western South America. Another reason is perhaps the selective pressures when estab-lishing a new species. One thing is true, though: three land bird species qualify as true “birds of prey”. One is the Galapagos hawk, a buzzard-like bird, and surprisingly there are two species of owls: the short-eared owl and the barn owl.
With so few rodents, how can an owl survive in the Galapagos Islands?
There are some rodent species in the Galapagos, and while some are introduced species, others are endemic, and some have become extinct. However, owls are not really rodent-specific eaters. They do hunt for other species, and in the case of the short-eared owl, it seems that is feeding behavior has changed a bit. In Galapagos they show nocturnal feeding habits, but it is easy to see them feed-ing in crepuscular times (right after sunrise and right before sunset). One show not to be missed is the walk at Prince Philip’s Steps on Genovesa Island, where in the brown-orange lava flows, owls camouflage as they search for storm petrels. MORE ABOUT OWLS
The other owl species is the barn owl and is more commonly found on inhabited islands and associat-ed with farm homes, abandoned structures, etc. With so few humans living in the Galapagos it is easy to see why so few barn owls are spotted, and certainly their population only reaches a few hun-dred individuals. It is still remarkable and unusual to see them, and probably the best opportunities are when visiting the highlands of Santa Cruz.
But how do owls see in such dark conditions?
One of the greatest adaptations in nature is birds’ nocturnal vision. Of all owls’ features, perhaps the most striking is its eyes. Large and forward facing, they may account for one to five percent of the owl’s body weight, depending on species. The forward facing aspect of the eyes that give an owl its “wise” appearance, also give it a wide range of “binocular” vision (seeing an object with both eyes at the same time). This means the owl can see objects in 3 dimensions (height, width, and depth), and can judge distances in a similar way to humans. The field of view for an owl is about 110 degrees, with about 70 degrees being binocular vision. By comparison, humans have a field of view that covers 180 degrees, with 140 degrees being binocular.
Internally, an owl’s eye has an abundance of light-sensitive, rod-shaped cells appropriately called “rod” cells. Although these cells are very sensitive to light and movement, they do not react well to color. Cells that do react to color are called “cone” cells (shaped like a cone), and an owl’s eye pos-sesses few of these, so most Owls see in limited color. Since owls have extraordinary night vision, it is often thought that they are blind in strong light. This is not true, because their pupils adjust fast, allowing the right amount of light to strike the retina.
Give it a try and find your short-eared owl in the Galapagos on board Yacht La Pinta. It is hard to guarantee an owl encounter on every island, but if your voyage includes the islands of Genovesa or Santa Cruz, then your chances are in the hands of nature.
Francisco Dousdebés – Galapagos Expert, Quito, May 10th, 2016 – Genovesa Island 0°31’N / 89°95’W
Barn Owl Image by igoterra.com :: Owl vision graphics by owlpages.com