I want to introduce this owl to you because since the 16th of March our pair of Northern Hawk Owls has been taking up quite a bit of my time and attention.  Before I tell you why, I would first like to describe this species. 

In the wild, you find Northern Hawk Owls in North America and North Eurasia (see map).  There are differences between the birds in the two territories in that the New World species (Surnia ulula caparoch) is darker and slightly bigger than the Hawk Owl from the Old World (S.u. ulula). 

Northern Hawk Owl in flight

The Hawk Owl has a rather square head with black edged face and yellow eyes.  The breast is barred and the back is brown.  It has a long tail and pointed wings.  It is  about the same body size and weight as a Barn Owl.  The shape explains its name, which in French we call Chouette Épervière; Chouette meaning owl and Épervière meaning Sparrow Hawk. 

Geographical differences in species

The Northern Hawk Owl lives in open coniferous forests and moorland in lowlands or mountains.  Not really sedentary, this owl moves widely within its area of distribution. 
Nests are in natural tree holes.  Usually a breeding pair has several nest sites and the female selects the most appropriate. The whole breeding cycle for the Hawk Owl is about four months, with 3-10 eggs begin laid between April and May.  Like most owls, the interval between laying each egg is about two days.

Diet during spring and summer consists mainly of voles and indeed their number and distribution varies according the abundance of this favourite prey.  However this species is an adapted hunter, eating small birds and mammals, frogs and occasionally fish.  In the winter when vole numbers decline, they will chase birds such as Willow Grouse.  It used to be thought that a large part of their diet consisted of Lemmings, however several studies have now shown that this is not the case.  They are active during daylight hours and at dawn and dusk, using various techniques to hunt, from a perch or in flight.  Their flight pattern is a straight line with fast wing beats, alternating with gliding.  They can also hover when hunting in an open area.

The Northern Hawk Owls' aviary

So, now to why our pair of owls has been of such great interest to me.  I started to work at the Hawk Conservancy Trust in January and I was glad to be given my own section on the park.  The first job each day is to feed and check the birds and aviaries.  I love to spend time around these aviaries.  Even though I do not have a favourite bird, I have been watching these particular owls so intently because they have recently produced two chicks.  Inside our aviary in the back right hand corner, you can see our owls’ large nest box. 

The excitement all started on about 16th March when incubation began; this is an approximate date as we spend as little time as possible in aviaries when birds are nesting, and do not peer into the nest box, even though we would love to know what is going on inside!  But we know something is up when the adults’ behaviour changes, for example the male starts to be more vocal and aggressive when we approach the aviary.  Also, when we give extra food and all of it is taken, we know there are more than two mouths to feed.  However we later discovered that the female had laid three eggs and incubated them for about 25 days, with the eggs hatching around 10th April.

The two juveniles

Unfortunately one of the chicks did not survive, however the remaining two made their appearances in May, the first on 14th and the second on 20th.  During the first weeks, we had to check regularly that the chicks were not getting too wet when it rained; they were unable to fly well enough at that stage to get back into the nest box unaided! 

Today, 25th May, the two juveniles spend all their time outside and their flying skills are improving daily.  They will be independent in mid to late June. 

The Northern Hawk Owls are not the only breeding pair to have chicks on my section of the park, but I don’t want to reveal all the new-borns at the Hawk Conservancy.  If you really want to know, you’ll just have to come and see for yourselves!

Credits:
Owls: a Guide to Owls of the World by Claus König, Friedhelm Weick & Jan-Hendrick Becking
Owls of the World by Rob Hume (illustrations by Trevor Boyer)