A Global First – Eurasian Eagle-owl Predation of a Porcupine in Israel
By Ezra Hadad, Green Patrol ranger, Israel Nature and Parks Authority
Eurasian eagle-owls are known to be fearless and to attack very large animals and even humans who get too close to their nesting site. The female, which is much larger than the male, vigilantly protects her newborns and fledglings, like all females. Male Eurasian eagle-owls are passive observers, at most emitting cries when danger is near. These raptors are known for hunting large animals like foxes, badgers, martens, cats and other mammals as well as large birds, including eagles, buzzards, falcons, hawks and all the other nocturnal raptors near their hunting site.
A recently published report documents the first evidence of Eurasian eagle-owl predation of a porcupine. In one of my visits in the summer of 2008 to an eagle-owl nesting site, under observation for research on eagle-owls in the Judean Lowlands, I found a large quantity of Indian-crested porcupine quills in a heap on a porcupine trail near an eagle-owl nest with two fledglings. I realized right away that something had happened there because it looked like the scene of a battle with an adult porcupine. But it didn’t occur to me that an owl had been involved.
Later, I photographed the female owl perched in a nearby tree in the evening. When I opened the photos on my computer the mystery of the quills was solved and I realized what had been responsible for the pile of quills near the owl’s nest. Two quills of an adult porcupine were impaled in her talons.
A porcupine and a marten family lived near the nesting site and their nighttime path passed nearby. That night, when a porcupine passed the nest, the female eagle-owl swooped down on it.
In the photo, red arrows mark the quills protruding from the eagle-owl’s talons.
Later observation of the nest revealed remains of predation of two young porcupines, and in another nest remains were found of another young porcupine including in the owl’s pellets. It’s absolutely crazy – an adult Indian-crested porcupine can weigh as much as 30 kg, four times the weight of a female eagle-owl. For these raptors, attacking a porcupine is more dangerous than attacking an adult fox, and this is the first documented case anywhere in the world of porcupine predation by an owl.
The Eurasian Eagle-Owl – The Story of the Research
Research and observation of eagle-owls began from a longtime dream-come-true. It all started more than 40 years ago, on the day I first encountered this particularly impressive nocturnal raptor on one of my patrols in the Judean Mountains. It was a thrilling up-close and personal encounter that left a powerful and lasting impression on me.
In the summer of 2005, as part of my work for the Israel Nature and Parks Authority Green Patrol, I conducted an extensive survey of raptor nests throughout Judea. During the survey I realized that there was a relatively large population of eagle-owls in the area and in that same year a great deal of data was gathered about their nesting sites. In 2006, I decided to launch a large-scale research project on the species. The research included visiting their nesting sites, observation and documentation of the growth rate of the nestlings until they fledged, the collection thousands of pellets and various food items at the eagle-owl nesting sites, from which 9,461 prey animals were identified. During this period, each year 10 nests were checked. The research revealed more than 50 eagle-owl nesting territories in the district of Judea, in an extensive study that continued until 2009, and in special projects that continued until 2015. One of these projects was a first-of-its-kind study in Israel in cooperation between the INPA and the Wild Animal Hospital involving nestlings that were found under various circumstances and brought to the hospital. The project – to place nestlings in adoptive eagle-owl nests – was very successful. The research is now in the writing phase, revealing numerous important findings about the importance of protecting nature and the habitats of this species.
There were surprises in terms of the distribution of eagle-owl prey, a field called zoogeography; the findings will be published in scientific journals in the near future. I was able to photograph thousands of pictures of this super-predator that is the largest nocturnal raptor in the world, the most valiant and successful of nocturnal raptors, mysterious, strong and quick, with large, powerful talons and a strong beak and that preys on animals ranging in size from a beetle to a fox. They hunt and consume any animal that doesn’t outsize them, and can attack animals that are larger than they are. They have almost no natural enemies. The eyes of this nocturnal raptor are large and orange, the color of fire, which give it a more vivid appearance and leaves a very powerful impression, one might say even frightening and chilling. Those eyes, sharp-sighted even in complete darkness, are a real masterpiece of evolution.
As noted, the study in the Judean Mountains revealed, that the eagle-owl preys on animals ranging in size from a beetle to a fox. They are extremely skilled at hunting in all kinds of habitats. They are very active hunters even in stormy weather; heat and cold don’t faze them. The female, which is larger and stronger than the male, usually hunts the large prey. It kills by stabbing the prey it with its long, sharp talons, and it knows how to break the bones of large animals like foxes or hares. Eagle-owls, usually the females, will attack large animals, even humans, if they get too close to their nest and their young.
Their hunting method involves perching on a high point on rocks, trees or poles, and surveying the open fields. Food is very varied, mainly mammals, and they also grab the young from the nests of other birds. The eagle-owl brings its prey back to its territory, especially the larger animals, and places the carcass on a picnic table to remove the feathers and dismantle it. Like all nocturnal raptors, eagle-owls swallow their prey whole. They can’t digest parts of bones, skulls, mainly of mammals and small birds, fur, teeth and insect exoskeletons. They excrete all this in the form of pellets. Eagle-owl pellets are very big and hard; it’s easy to differentiate them from those of other birds. They are an average of 7–10 cm long and can sometimes reach a length of 15 cm.
Of the 9,461 food items the research project discovered in the eagle-owl pellets, 72.2% were mammalian, 24.4% were avian, 0.9% were reptiles and 2.4% were insects. There were also some surprises – fox, a badger, cats, weasels, a marten, and, in first case ever documented anywhere in the world – young Indian-crested porcupines. The quantity of bat and toad predation was very impressive, one of the highest in the world. Among birds, it was found that the eagle-owl is particularly fond of nocturnal raptors, but remains of large diurnal raptors were also found, including short-toed eagle, and long-legged buzzard. Among the reptiles was an impressive quantity of javelin sand boas.
The owl reaches sexual maturity at the age of about one year, and marks his territory. Couples form in the fall, in October, and they court from December to February. They usually build their next on rocky cliffs, steep slopes, quarries, and other such places. The male begins to supply food a few weeks before the female lays her eggs and begins to brood. The female usually flies toward the male to receive the food, mostly near the nest. Mating also usually takes place near the nest on protruding rocks. Only the female sits on the eggs; a few days before the first egg hatches she can be seen brooding for two days straight. The female lays the eggs at the end of February in a small niche she has dug. She lays between two and four eggs, usually two to three and in rare cases she lays five. She begins to brood after laying her first egg, and three to four days pass between the laying of each egg. The gestation period is from 34 to 36 days. The eggs are white and resemble chicken eggs but bigger. When the baby birds hatch they weigh about 50 grams and their feathers are white and fluffy.
The main cause of death among owls is electrocution, which occurs when they penetrate transformers transmission towers when hunting prey such as pigeons. Electrocution impacts the owl population, causing them to leave their territories. Owls are one of the species most effected by electrocution, to the point of concern about the population. In some places, barbed wire installed around open spaces are a danger to owls. Owls have also been found run over on roads in their hunting territory. Many owls are harmed by humans due to superstition, hatred and ignorance. Additional harm comes from curious but irresponsible nature lovers and photographers.