House Hunters: Shrike Edition
Posted onMarch 21, 2023by|, ,
Shrikes are among the first migrants to return to Ontario breeding grounds, showing up as early as late March, and when they arrive, the search for territory begins. Unfortunately, just like our human housing market, the shrike territory market is also HOT!
When searching for prime real estate, shrikes must take into consideration a slew of important habitat characteristics in order to successfully attract a mate, build a nest and brood successful offspring. Therefore, having access to high-quality real estate is crucial to survival. As shrike “shop” around they must consider the following before closing the deal.
First and foremost, shrikes are grassland birds, which means they prefer to reside in mostly open areas with scattered low trees and shrubs. In Ontario, most shrikes breed in either the Carden Alvars or the Napanee Limestone Plain. Many of the alvars around the Great Lakes basin have been degraded by agriculture and other human uses, which has contributed to the fast decline in shrike abundance. These unique and rare biological ecosystems are based on a limestone bedrock with thin topsoil, which result in more sparse vegetation. Shrikes are visual hunters, so sparse vegetation aids shrike in their search for and capture of prey.
The beautiful Carden Alvar. Photo: Ontario Parks
Shrike need a place to call home, and for them a high-quality nest tree is about as ‘home-y’ as it gets. Nest predation is an ever-present threat for shrike though, so finding a tree that provides both visual and physical protection from home invaders is ideal. Their favourite spots to set up roost are hawthorns, red cedars or, less frequently, white cedars. All of these shrubs/trees provide a great deal of concealment for their nests, and the fact that hawthorns also offer many spots to impale prey on their thorns makes them the most popular nesting trees for shrikes.
From left to right, hawthorn shrub, red cedar and white cedar. All are prime shrike nesting species!
There are many reasons why having numerous lookout perches are important for shrikes to consider when moving in to their breeding territory. Shrikes will first use lookout perches to establish their property lines (or breeding territory boundaries), and then to defend those property lines from unwanted visitors. Scanning their territory from these perches, if a predator is detected shrike will make alarm calls and chase them out of their territory. How cool!? They are their own security system! A useful lookout will be a high, exposed perches such as hydro poles, deciduous trees or snags (dead trees), where it’s easy for the shrike to spot any predators, whether airborne or on the ground, that are encroaching on their territory. They don’t need many of these, but it is important for a shrike to have one or two lookout perches so they can defend their territory from various angles.
Spotted! An angry shrike, on a snag, defending its territory from a red-bellied woodpecker. Photo: P. Rathner
In addition to lookout perches, shrike must assess real estate for hunting perches. How do hunting perches differ from lookout perches, one may wonder? Well the answer is in the name. In contrast to the tall lookout perches shrike use to keep an eye on their territory, hunting perches are characterized as low perches up to 5 metres high, and are generally spaced 10-20 metres apart. Shrikes are able to spot prey from up to 30 metres away, which is why this spread of perches is advantageous for them. Shrikes most often look for fence posts, small trees or shrubs, rocks or utility wires as hunting perches. How innovative! With access to high-quality hunting perches, shrikes are able to use their unique predatory hunting strategy to locate and capture prey items. We definitely don’t want a ‘ hangry’ shrike!
Yes, shrikes use man-made structures, such as this utility wire, for hunting perches as well. Photo: S. Silko
Of course, once a shrike captures food, they must kill it Hey, we didn’t nickname them “The Butcher Bird” for no reason! Shrikes use a unique method of food manipulation where they impale large prey items in order to hold them still while they rip off bite-sized pieces, because they don’t have strong feet/talons. Options are important when choosing new real estate and for shrike having a variety of impaling site is key! Shrikes have been known to impale their prey items on dense, multi-stemmed or thorny shrubs or they can get pretty innovative and use barbed wire fence to impale their food. If the prey item is large enough shrike leave their impaled prey on their impaling sites for later. Shrikes enjoy a well-stocked pantry! The impaled food items also serve as mating displays to try and lock down their lady shrikes by presenting them with an easy food source. How thoughtful! So, in the quest for the best real estate, impaling sites are especially important for securing a mate and food handling.
A shrike perched on barbed wire fence, a perfect spot for future prey impaling. Photo by L. Kirtley
Making use of a sharp twig to impale this insect. Photo: P. Rathner
Shrike have a lot to consider when they arrive on their breeding grounds. Finding the right real estate is central to their breeding success, and the success of their future offspring!
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