Monday, June 17, 2013

Really Weird Birds: Shrikes

 There are thirty-one species of shrikes throughout the world. 

Shrikes are medium-sized (~20 inches in length) passerine birds of the family Laniidae, the name being derived from the Latin word for butcher.  Some shrikes are also known as "butcher birds" because of their unusual feeding habits.  Their beaks are hooked, like birds of prey, indicating their predatory nature.  Most shrike species are found throughout Eurasia and Africa.  There are just two species found in North America: the Loggerhead and Northern Shrikes.
Loggerhead Shrike
Shrikes are birds of open country, especially grasslands and overgrown fields with scattered shrubs and trees.  They consume insects, other invertebrates, amphibians, small to medium-sized reptiles, and small mammals and birds.  The design of their beak allows them to quickly kill their prey with a bite to the back of the neck.  They use their beaks to transport small prey, and their feet to carry something larger up to their own body mass.  But what they then do with their prey is unique.  They impale their captured meal on a thorn, a sharp twig, or even barbed wire.  They can then proceed to rip and tear it apart into bite size pieces!  If the prey is too large to eat in one sitting, the shrike will leave it on its spike and return later to finish. 
Northern Shrike with impaled mouse
Shrikes are predators, but they lack strong feet and talons for holding prey down while eating it.  Therefore they have instead evolved this unique adaptation for feeding as well as for courtship displays.  In some species of shrikes, the larger the item the male impales, the more desirable he is to the female.  Also a study done in Poland on the Great Grey (in Europe this is the common name for the Northern Shrike species) Shrike showed that males impaled their prey faster and with less attempts per impaling than females.  The location of impaled prey also differed.  Males impaled prey in more visible places, especially during the courtship and mating season, whereas females found concealed locations.
Vlad, a Loggerhead Shrike who resided at WBS until he passed away in 2011 from old age
Males will also perform a courtship dance and song in order to attract a mate.  They will bow, shiver their wings, and zigzag up and down a branch.  Some shrikes will even impress the ladies by impaling shiny or colorful objects on a thorn.  Shrikes are typically monogamous and together build a cup shaped nest off the ground.  The female incubates the eggs while the male brings her food.

Unfortunately, a trait shared among shrikes around the World is that many species have suffered population declines.  The Loggerhead Shrike population has been decreasing across much of North America and has all but disappeared from many areas, to the extent that captive breeding programs have been started in an attempt to save some populations of this bird.

Biologists believe that habitat loss and pesticides are the chief reasons for their decline.  In Missouri, the Loggerhead Shrike is listed as a Species of Conservation due to its rapidly declining populations.

Submitted by Sara Oliver, World Bird Sanctuary Naturalist


Doug said...

Nov 6,2014. I have just spent 20 minutes watching a Shrike eating a Sparrow in the bush outside my bedroom window.I had never seen such a thing so I had to google it to find out what bird it was.

Photog said...

Congratulations, Doug. You've just had the opportunity to watch something very few people have had the opportunity to see!