Tag: sexual dimorphism

A Very Cooperative Rough-legged Hawk

In a previous post I mentioned that I had been encouraged by the number of Rough-legged Hawks (roughies) I’ve been seeing this fall.  Well I’m delighted to report that the situation continues to improve.  On virtually every photo expedition over the last few weeks I’ve seen several of them and on two recent trips we’ve made about a dozen sightings of different individuals each time.  However getting good photos of them is a different story altogether.   After a season in the high arctic they’re very unapproachable and even when I have been able to get reasonably close they’re usually perched on an unattractive sign or post and take off away from me.  All that changed a few days ago though when we found one very cooperative bird.  This species has the most different male and female plumages (sexual dimorphism) of all our buteos and I’m quite sure this is a light phase female.     1/1000, f/6.3, ISO 640, 500 f/4, 1.4 tc We first spotted this bird on a low wooden post that resembled a piling and I was pleasantly surprised that it let us approach (in my vehicle) with no signs of nervousness.   It was early on a cold, frosty morning and while looking through the viewfinder I assumed that the material on top of the post was spider silk that had collected dew and then frozen.  But after looking at the photos at home I wasn’t so sure so the next day I walked over to the post to check it out.   Duh – should have known.  It was  frosted bison fur.  This was Antelope Island…

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Fish Eating Northern Harriers

 As I’ve mentioned before in this blog, the winter of 2008 was a particularly brutal one in northern Utah.  During January and February there was much more snow than usual and it was bitterly cold.  During most winters our Northern Harriers rely primarily on voles as a food supply but in 2008 with the voles under the deep crusty snow our harriers were desperate for food.  Birds of North America Online provides extensive information on the dietary habits of harriers.  It lists small to medium-sized mammals (primarily rodents), birds, reptiles and frogs as harrier food sources, stating further that the diet of harriers during winter in their northern range (which includes northern Utah) consists of voles “almost exclusively”.  I can find no mention of harriers eating fish, ever! Each year in early February some of our wetlands managers treat some of our ponds with rotenone (a chemical that prevents oxygen from being absorbed across fish gill membranes) in an effort to control the invasive and damaging carp that do so much damage to the emergent vegetation which is so vital for waterfowl.  So, in 2008 for a few weeks, our desperate and starving harriers began to eat fish!  In the three winters since then I have never seen harriers eating fish even though the dead carp are always plentiful after the rotenone kill.    1/1250, 1/1000, ISO 500 Many of the carp are brought to the shores or ice surface by Bald Eagles which makes them available to the harriers who generally cannot retrieve them from the water.      1/1250, f/8, ISO…

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Northern Harriers Battle over a Mallard

Occasionally we have brutally cold winters here in northern Utah.  It’s my opinion that unusually cold temperatures when combined with thick crusted snow gives harriers little access to their staple food around here – voles.  Survival then becomes tenuous for the harriers and they’re forced to move on to other food sources like small birds, dead carp and waterfowl.   When a large meal like a carp or duck is available many harriers often fight over the food item and they do so with ferocity.   During less stressful times of the year I often see these birds skirmish but then it almost seems like a playful interlude that they do simply for “fun”.   Not so when it’s very cold and food is scarce – then it’s deadly serious and incredibly interesting to observe and photograph. First, a disclaimer.  Some of the photos I’ll present here would wither under the scrutiny of critique because of cut off or clipped wings, missing eyes or heads, lack of catch lights and difficult and rapidly changing lighting conditions.  My intent here is to show the behavior with the best images I have but some of them do have obvious flaws.  The calm before the storm I didn’t see harriers make this Mallard kill but it was still fresh when I came across this bird on the duck.  At first I though I’d simply be photographing the harrier calmly enjoying its meal but I was very mistaken.   Thinking about challenging the larger bird for the meal It didn’t take long for other birds to challenge her for the Mallard.  Some were timid…

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Northern Harrier Males – “Grey Ghosts”

The degree of sexual dimorphism (the condition in which males and females of a species are morphologically different) in Northern harriers is exceptional among birds of prey.  Many raptors are sexually dimorphic in size (see my “Great Horned Owls on the Farm” post) but Northern Harrier males and females are distinctly different in both size and color.    Adult female Northern Harrier This bird is a juvenile female, identified by the mostly solid rufous chest and dark eye.  The adult female would look much the same but with a streaked breast and a lighter colored eye.   By weight, females are about 50% heavier than males.  Both sexes have the distinctive white rump patch that is so difficult to photograph without blowing the whites.       Adult male Northern Harrier Adult males are gray above, much lighter below and have black wing tips.   And their bright yellow eyes are quite distinctive.       Adult male hunting Juvenile birds of both sexes resemble the female in plumage color so relatively few adult males are seen and photographed.  For this reason mature males have long been referred to as “Grey Ghosts”.       Perched adult male Whether perched or in flight many believe the adult male harrier to be one of the most beautiful raptors.    Adult male flying past Phragmites  Eye color in the males can vary from orange-yellow to lemon yellow.  At times they’re so bright that some folks after seeing my images have thought that I had increased their saturation for effect during image processing.  I hadn’t and I don’t.    …

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Great Horned Owls on the Farm

For perhaps twenty years now there has been at least one pair of nesting Great Horned Owls on the farm where I grew up near Cut Bank, Montana.  They were never there when I was a kid but they’ve sure taken to it since.   This farm still seems like home to me and I return to it at least once every year for a visit with family and of course to check up on the owls.  It’s the perfect place for these birds as it’s isolated, there are many old barns and granaries for the owls to find sanctuary and mice, voles and the ubiquitous Richardson’s Ground Squirrels (gophers) are everywhere.  Both the owls and I love the place! Great Horned Owl in a barn cutout Most often I prefer my birds on natural perches but there’s just something about owls and old barn wood that appeals to me.  I think owls, particularly Barn Owls and Great Horned Owls, often just seem to “fit” in many rustic settings.  In the image above, I like the warm tones of the bird contrasting with the cooler tones of the black background and some of the wood.  Juvenile (no “horns” yet) in warm, early morning light The youngster above was sitting in an east facing cutout in an old granary just as the sun came up.  The effect of the warm light on both bird and wood is fairly dramatic (no saturation added).  This juvenile is wet from the dew, thus the “spikiness” on the top of the head.  They look very different from the…

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