Impaling prey is a behavior only found in two bird species, the Northern Shrike and Loggerhead Shrike. Scientists believe this type of hunting behavior has evolved from other species of birds that wedge their prey before consuming. These shrike species are the only songbirds (passerines) that hunt other birds. They also hunt small mammals and insects. They do not have strong talons or massive beaks like raptors such as falcons and hawks do. However, they have a distinctive sharp point at the tip of its beak to tear into its prey. Once their prey is captured, they will impale their catch on a thorn, barb wire, or even branches in small bushes. When shrikes’ vertebrate prey is impaled on a sharp object they are then usually decapitated and, in most cases, the brain consumed before other body parts. Field observations confirm that the ability to impale prey develops in the young of these species in the first 4–5 weeks after fledging. They have evolved this behavior to reduce handling time of their prey and reduce any risk of injury. They are also known to hunt toxic grasshoppers. They will impale the grasshopper and leave it in a cache (storage spot) while the deterrent chemicals decompose and the grasshopper can then be later consumed. Caching is used by shrikes to demarcate territories, store food for inclement weather or periods of stress in the breeding cycle,and divide labor between the breeding pair. During the period of prenuptial display, male shrikes were observed to impale inedible objects such as rags, snail and eggshells, or even bread crusts, ostensibly to boost the visual effect of the cache. The larger the cache the higher the reproductive success of male Shrikes.
Posted By Carlos Varela (week 3)
I think this may just be the coolest thing I have ever heard. I definitely would not think that this small little song bird would brutally murder other small animals; pretty impressive. Also the fact that they use tools in their environment since they lack raptor like characteristics shows that they are able to think at a pretty complex level. Did the article by any chance mention if using thorns and barb wire is a learned or innate technique? I am really surprised such a species would not have developed more external structures to catch this type of prey. The fact that they eat toxic grasshoppers is also very interesting because it is a great example of the ‘arm race’ between predator and prey organisms. Did the article talk about how this behavior may have evolved? Lastly do you know/or did the article state any additional behaviors used by these birds to mark their territory or attract a mate, or is hunting and storing the most important mode of communication?
ReplyDeleteGreat Post!!
Posted by Jackie Connolly
Great Post! How do these birds learn to impale their prey? Do parents teach their offspring to do this, or is it an innate behavior? Also, how do the birds know that the grasshoppers are toxic and that impaling them and waiting to eat them will rid them of the toxins?
ReplyDeletePosted by "Sarah Benjamin"
Wow,,this is something that i have never heard of before. could it be that the grasshoppers shown some type of coloration to show its level of toxics? Otherwise like what Sarah mentioned how can they tell if the grasshoppers are lethal to consume? Why do you think that these birds had evolved such behavior? If it beneficial to them? I just cant believe that the little tiny birds can be so brutal when it come to its prey. It's very interesting how they consume the brain before the body part, the brain is obviously softer part of the body so is that why they eat it first? and why do they let the body partially decay before consuming? to soften the flesh?
ReplyDeleteposted by "Tiffany Phan"
ReplyDeleteThis comment has been removed by the author.
ReplyDeleteWow. Do they have any idea why they eat the brain first? What species of birds wedge their prey before they eat them? I'm a little confused as to what wedging means. I can't believe they eat other birds. How do they manage to catch them?
ReplyDelete-Emily Crete
I know there are a bunch of comments here but I just can't help it. This is the coolest adaptation I have heard in a long time. I can't help but parallel this to our ancestors hunting with spears. It really is a fast, effective way to hunt prey. Has there been research into this species evolutionary history? When did this impaling behavior first begin to appear? If this is one of the only species that do impale I'm thinking that a common ancestor was not too long ago.
ReplyDeleteJust awesome.
-Jillian O'Keefe
To clear up confusion, impaling is defined as the skewering of prey on a sharp projection; “wedging” is the placing of the item in the fork of a substrate. The cache the males build is a way to attract females. The males also use colorful impaled inedible objects to visually attract females. The article states the larger the cache and the more decomposing prey stored in the cache the more reproductive success. In addition, polygynous breeding occurred in them more often. Sorry, but I could not find enough information about their evolution to answer some of the questions.
ReplyDelete-Carlos
this at first caught me a little off guard, i didn't think such a small bird could be this violent when killing its prey. The way the bird uses the sharp point at the tip of the beak to minimizes the amount of time fighting is truly amazing.
ReplyDelete-Stephen Chiricosta