A few weeks ago I went to visit the Morley Nelson Snake River Birds of Prey National Conservation Area where I conducted my Boise State University thesis research on wintering raptors. While there was unfortunately little chance of encountering a Rough-legged Hawk in late June, I still wanted to see how the area had changed since I last visited in late February. While a few stragglers remained, a majority of the ground squirrels that had been so common back in February were now either in aestivation for the hot summer months, or had already been turned into dinner by the plethora of raptors that inhabit the area.
Swainson's Hawk. Photo by Neil Paprocki.
During the hottest summer months of July and August, few raptors actually reside within the Bird of Prey Area as most migrate elsewhere in search of more abundant food resources. One of the exceptions to this is the Swainson’s Hawk, which is a relatively late breeder, and stays in the area until August and September before leaving for their fall migration. These long-distance migrants will travel all the way down to the Argentinian Pampas in the southern hemisphere for the winter.
Long-billed Curlews. Photo by Neil Paprocki.
One aspect of this past winter and spring that has me worried about the Bird of Prey Area was the extreme lack of precipitation. The annual grasses were already dry and brown when I visited in late June, providing an excellent fuel source for wildfires. While fire management has improved dramatically in the area following the devastating wildfires of the 1980s, they do still occur on a regular basis. This year could be a particularly bad fire year given the lack of precipitation this winter and spring. As I write this post, the skies above Boise are already tinged a dull brown from other wildfires ignited by recent storms throughout the area. Unfortunately, it may be just a matter of time before one flares up in the Birds of Prey Area. Hopefully, whatever wildfires do occur are contained to areas that have already burned so we do not lose more of our precious native sagebrush habitat that wildlife depends on.
Adult Ferruginous Hawk. Photo by Neil Paprocki.
Rock Wren. Photo by Neil Paprocki.
With wildfires currently in Idaho, Oregon, and Nevada, many thousands of acres of native land are being burned at a rate far faster than natural levels. This is due to the prevalence of invasive grasses and forbs such as cheatgrass, medusa-head rye, and russian thistle (more commonly referred to as tumble-weed). These invasives shorten the fire-return interval (the time period between wildfires at the same location) to less than 10 years when fire in the Sagebrush Ecosystem naturally occurred only once every 40-100 years. This shorter fire-return interval means slow-growing, native shrubs such as Sagebrush do not have time to re-establish before another fire blows through, thus creating a feedback loop perpetuating the spread of invasives. While there is little we can do to prevent wildfires ignited by natural causes (i.e. lack of precipitation and lightning), we can be more aware of our surroundings so that less human-induced wildfires are ignited.
Some things we can all do to prevent human-induced wildfires: 1) do not throw your cigarette butts out the window in the middle of summer (or any other time of year for that matter!); 2) be careful not to drive over tall, dry vegetation where sparks from the undercarriage of your vehicle can start wildfires; 3) do not have campfires in areas where vegetation is really dry or winds are likely to disperse embers; 4) if campfires must be built, keep them small and remember to put it out completely using water and a shovel to bury the hot coals; and 5) just generally be aware of your surroundings so you know where wildfires are most likely to ignite. We are losing enough native habitat as it is from natural causes that we don’t need to compound the effect through our own lack of knowledge or understanding. We want to preserve this native habitat so that we can continue to conserve the beauty and bounty of nature.
Prairie Falcon. Photo by Neil Paprocki.
Am I becoming obsessed with Rough-Legged Hawks? Perhaps, but for good reasons I swear! There is relatively little known about the year-round ecology and life history traits of this high arctic breeder. This is all the more surprising when you consider how common this raptor can be on it’s wintering grounds in the continental United States. Most of what is known about Rough-Legged Hawks has been inferred from small scale studies on their wintering grounds (my Master’s thesis research included), with few studies documenting their breeding and migration ecology. I hope to be able to study these beautiful raptors in greater detail soon, but for now I thought I’d take some time to familiarize some of you with field techniques I use to age and sex the species.
- Photo 1. Adult Male Rough-Legged Hawk. Photo by Yozora Tadehara.
Rough-legged Hawks are unique among hawks (also called Buteos), in that they can be aged AND sexed fairly reliably using plumage characteristics in their feather patterns. Most hawks can only be aged (juvenile vs. adult), using plumage characteristics. Let us start with the bird pictured in Photo 1. First, we see this individual has the trait common among all Rough-legged Hawks in it’s dark “wrist”, or carpal, patches (A). All Rough-legged Hawks have these, although they can vary quite a bit between individuals. The second trait we see that is also common among all Rough-legs is the subterminal, or sometimes terminal, tail band (C). This individual is an adult male, which are unique by sometimes have multiple tail bands, as we see this individual has a faint second tail band above it’s well-defined subterminal band. Lastly, we can see perhaps the trait that most often distinguishes adult males from females, which is the lack of a dark “belly” band across the lower abdomen (B). There is considerable variation among adult male plumages (which are not all covered here!), so lets look at two more individuals:
- Photo 2. Adult Male Rough-Legged Hawk. Photo by Yozora Tadehara.
- Photo 3. Adult Male Rough-Legged Hawk. Photo by Beth Orning-Tschampl.
We can see that the adult male in Photo 2 is fairly similar to the adult male in Photo 1. A few key differences to note: The first being that the male in Photo 2 has a considerably darker belly than the male in Photo 1. In fact, Photo 2 almost makes it appear as if this individual has a belly band (an adult female and juvenile trait), however the picture is backlit, so keep in mind that light can play tricks on you. The second difference between Photo 1 and 2, is that the adult male in Photo 2 has a much more well defined second tail band (A). Adult males can sometimes have anywhere from 1 to 5 (or more) tail bands.
The last adult male I want to share with you is pictured in Photo 3 and is vastly different from the previous two individuals. This adult male has heavily “mottled” feathers (or feathers with markings on them) on its underwings, as well as chest and belly. These feathers are so heavily marked that the characteristic carpal patches of Rough-legs almost fade into these markings, but still remain slightly darker than the rest of the underside of the bird. We can also see another trait common among all Rough-legs (except some dark morphs), which is the presence of a white-rump patch at the base of the top-side of the tail (A). This can lead some to easily confuse Rough-legs with Northern Harriers, which also have a conspicuous white-rump patch. Lets quick re-cap the two best defining characteristics of most adult males: 1) lack of a well-defined, dark belly band, and 2) more than 1 tail band (sometimes). Now lets move on to adult females:
- Photo 4. Adult Female Rough-Legged Hawk. Photo by Robert Miller.
Right away we see a difference in Photo 4 from all the previous birds. This bird has a clearly defined, dark belly band (A), coupled with a single well defined subterminal tail band (B). These two traits help identify adult female Rough-legs. Photo 5 is another adult female, where we can again see the dark belly band, along with the single subterminal tail band (C).
- Photo 5. Adult Female Rough-Legged Hawk. Photo by Robert Miller.
Adult females are most often confused with juvenile Rough-legs, which cannot usually be sexed unless you have them in the hand. This confusion results from the dark belly band common to both adult females and juveniles. A juvenile Rough-leg:
- Photo 6. Juvenile Rough-Legged Hawk, sex unknown. Photo by Robert Miller.
The biggest difference between juveniles and adult females is the lack of a well defined tail band in juveniles (A). We can see in Photo 6 that this bird has a broad, dusky tail band that gradually fades into the rest of the cream colored tail. Another key characteristic of most juveniles is a general lack of mottling, or markings, on their underwing feathers (B). To see this more readily, lets compare Photos 4 and 6 side-by-side:
- Photo 7. A juvenile (left) and adult female (right) Rough-Legged Hawk. Photos by Robert Miller.
Now lets look at another juvenile that is considerably lighter, and has almost no tail band at all (very light):
Photo 8. Juvenile Rough-Legged Hawk. Photo by Neil Paprocki.
So now you are an expert in aging and sexing Rough-Legged Hawks right? Well maybe. As with most things in life, nothing here is absolute. Some key considerations and difficulties can arise: 1) These are all pictures of birds in flight, and perched birds are often times much harder to age and sex, although the belly band of juveniles and adult females is still conspicuous, 2) There is evidence in the scientific literature (Clark & Bloom 2005) that some adult males can exhibit adult female characteristics (namely a dark belly band, among others) after their first feather molt, so they are still retaining those juvenile belly band feathers while exhibiting other adult traits, and 3) Adult females can often have varying degrees of belly bands, with some showing lighter bellies indicative of adult males, while some can also show more than one tail band!
Hopefully this will be useful to some of you for the remainder of the winter, as Rough-Legs will sometimes stick around on their wintering grounds as late as April/May before heading back to the arctic to breed. But you can certainly use this guide for next winter! I’d welcome any and all photos or questions you have on Rough-Legged Hawks. I personally love seeing the wide-range of plumages this species can show. Please direct them to my e-mail at firstname.lastname@example.org. Below are some useful references I have used to help me identify Rough-Legs, and other raptors.
- Wheeler B.K. and W.S. Clark. 2003. A Photographic Guide to North American Raptors. Princeton University Press.
- Liguori J. and D. Sibley. 2005. Hawks from Every Angle: How to Identify Raptors in Flight. Princeton University Press.
- Bechard M.J. and T.R. Swem. 2002. Rough-legged Hawk (Buteo lagopus). The Birds of North America Online (A. Poole Ed.). Ithaca: Cornell Lab of Ornithology.
- Clark W.S. and P.H. Bloom. 2005. Basic II and Basic III Plumages of Rough-Legged Hawks. Journal of Field Ornithology 76: 83-89.
It is with some sadness that I must admit the purely fun part of my thesis research at Boise State University’s Raptor Biology program is now deceased. I ask: what could be more enjoyable than standing outside all day counting birds of prey? Unfortunately the only answer I have for that is writing, writing, and more writing! Perhaps I am being a bit dramatic, as this is the part of my research experience where I find out exactly what all that winter raptor data I collected means. I will continue updating this blog with my research findings, and other fun tidbits (such as a photographic ID to aging and sexing Rough-Legged Hawks!) as they come along.
The Snake River Canyon. Photo by Neil Paprocki.
For those who don’t already know, I will eventually be looking to see how winter raptor numbers have changed in southwest Idaho over the last 20 years, and how these changes have been affected by habitat and climate change. Until then, here are the raw count totals from November 15, 2011 – February 28, 2012 inside the Morley Nelson Snake River Birds of Prey National Conservation Area. And some photographic highlights from the last month and a half!
Figure 1. Raw raptor species totals for the 2011-12 winter in the Morley Nelson Snake River Birds of Prey National Conservation Area. Northern Shrikes are considered an "honorary raptor" in my book.
Adult Female Rough-Legged Hawk. Photo by Robert Miller.
Adult Ferruginous Hawk. Photo by Robert Miller.
Juvenile Rough-Legged Hawk and Adult Golden Eagle. Note the size difference. Photo by Yozora Tadehara.
Juvenile Rough-Legged Hawk. Photo by Neil Paprocki.
Melanistic Adult Male Northern Harrier. Photo by Rob Miller.
I wanted to quickly update everyone on the reaction we’ve been receiving from experts regarding the dark Northern Harrier Rob Miller, Liz Urban, and I saw last month in Idaho. Rob received an e-mail from Bill Clark, potentially the most experienced raptor identification expert in North America, and author of A Photographic Guide to North American Raptors. Bill says, “About your harrier. It is most certainly an adult male Nothern Harrier and most certainly melanistic.” This is excellent news! While we knew it was a dark harrier, it is always great to get confirmation from an expert in the field. Bill went on to suggest we publish our account, along with some photos of the bird in a short field note, similar to this article published by Chad Olson in 2000. We have not seen this bird again since our first siting, however I will be conducting road surveys next week along the same route where we saw this bird in January. Keeping my fingers crossed!
As many of you already know, the 2011-2012 winter has been a great one for owls. Especially Snowy Owls. I was lucky enough to make it out to Nampa, Idaho on December 31st to see the pair of Snowy Owls that took up residence in an agricultural field for the better part of two months. However, I had yet to see a Snowy Owl during any of my winter raptor surveys in the Snake River Birds of Prey National Conservation Area. That is, until today!
Adult Male Snowy Owl. Nampa, Idaho. Photo by Morgan Peters.
I was approaching one of my point count sites located near Kuna, Idaho in the middle of an agricultural field on the edge of my study area. Too busy locating two American Kestrels, a female Northern Harrier, and an adult Ferruginous Hawk on my way to the point, I almost missed what flushed directly in front of me! Right on top of a boulder pile where my point count site was located a male Ring-Necked Pheasant, along with a Snowy Owl flushed not 20 feet ahead of me out of some tall weeds! The bird immediate flew out of sight, but not before I was able to count it as I clicked my stopwatch on. It happened so fast that I was unable to snap any photos, and I was not able to located the bird again after the 20 minute point count, with limited access to the private land around me. However, I do have several photos here of the Snowy Owls from Nampa, Idaho: courtesy of Morgan Peters!
Adult Male Snowy Owl. Nampa, Idaho. Photo by Morgan Peters.
I thought I would also include some photos of other owls I have seen during the winter months the past two years. These are all Short-Eared Owls, with a few straggling Burrowing Owls. I have seen 7 Short-Eared Owls so far this winter, and saw my first Burrowing Owl on January 31st!
Short-Eared Owl. Photo by Beth Orning-Tschampl.
Short-Eared Owl coming in for a landing. Photo by Neil Paprocki.
Burrowing Owl. Photo by Jeremy Tout.
Three times every winter I drive road transects looking for raptors with other biologists for my Master’s Thesis work at Boise State University. Monday January 9, 2012 was one of these days. I was out with fellow raptor biology graduate student Rob Miller, and fellow biologist Liz Urban, who just recently defended her Master’s thesis work on Urban Cooper’s Hawks in Tuscon, Arizona. While driving along a bumpy dirt road thickly covered in old russian thistle within the Morley Nelson Snake River Birds of Prey Area, we flushed up a raptor little more than 10 feet from the road. The bird quickly flew away and landed down in some sagebrush less than 50 meters from the road. We all looked at each other and said: What the heck was that?
Rob and I climbed out of the truck, Rob lugging his camera-with-token-huge-lens attached (wish I had one!), and proceeded on foot through the sage hoping to flush the bird again to get a closer look. Sure enough the raptor flushed and we got a pretty good look as Rob snapped away grabbing a few good pictures in the 5 seconds we had before the bird flew out of sight again.
The bird was unlike anything Rob, Liz, or I had ever seen. First, it was definitely a Northern Harrier. These raptors fly low to the ground searching for rodents and birds using mostly sound to detect their prey. All of the male Northern Harriers I have ever seen have a conspicuous white rump patch, are slate gray on top, and bright white below with black wing tips. See the photo below of a juvenile harrier.
Juvenile Norther Harrier. Note the white-rump patch. Photo by Beth Orning-Tschampl
However, this bird was totally dark. Both on top and from below on the under-wing coverts, the bird was solid dark gary. Also, the characteristic white-rump seen on almost all Northern Harriers was noticeably absent on this individual! However, the bird is definitely an adult male as we see the black wing tips and yellow eyes present in adult Northern Harriers. We all thought, what the heck is going on? Are there different color morphs of Northern Harriers? None of us had heard of this being the case.
Dark Male Northern Harrier? Photo by Rob Miller.
Upon returning to the lab for the day. I asked my lab mate Eric if he had ever heard of dark Northern Harriers. He said yes, but that he thought they did not exist. Upon seeing Rob’s picture however, he was convinced this was at least a melanistic bird: meaning it has some genetic mutation for creating darker feathers, much like an albino would be. Researching further, I discovered an article from Birding in 2009 by noted raptor expert Jerry Liguori: Read the article here. In the article, Jerry has a distant photograph of a dark Northern Harrier and says “There are now three known records for North America of dark harriers, and this is the only one photographed.” Could we have possibly seen the fourth and only second dark Northern Harrier to be photographed in North America?!?! I think potentially so, and we have an e-mail out to raptor identification expert Bill Clark seeking his opinion on the matter. We will keep you all posted…
From what I have been hearing around the country, Boise Idaho is not the only place receiving record low totals of snow fall this winter. Maybe it is just going to be one of those years…. Although I do keep a sliver of hope out there for snow eventually. Aided by the nice weather, surveys have been progressing well since my last blog entry. As you may notice from the raw numbers below, there have been considerable jumps in the count totals for a few species, especially Rough-Legged Hawks and Golden Eagles.
Rough-Legged Hawks are here in full force, and it is rare NOT to see one during a survey this time of year. Stayed tuned to next months blog post where I will dive into these reclusive raptors in more detail, and also provide a short lesson on how to age and sex this species by their plumage/feather patterns. Golden Eagles have taken a considerable jump as well, and this may be due to where I have been surveying within my study area. Golden Eagles seem to hang out closer to the Snake River Canyon and further away from human developed/agricultural areas than most other raptors. These birds breed on cliff ledges in the canyon starting in February and March, and they may be staying closer to home in an attempt to secure the best breeding location over the coming months.
Prairie Falcon posing for the camera. Click for a larger view. Photo by Neil Paprocki.
My next entry will be closer to the end of the season in February, and after that I will eventually detail how these numbers have changed over the course of 20 years, and what that might mean for certain raptor species. For now, here are the raw count totals from November 15 through January 7, 2012 inside the Morley Nelson Snake River Birds of Prey National Conservation Area:
Figure 1. Raw raptor species totals through January 7, 2012 in the Morley Nelson Snake River Birds of Prey National Conservation Area. Northern Shrikes are considered an "honorary raptor" in my book.
Juvenile Rough-Legged Hawk. Photo by Neil Paprocki.
A month into the winter raptor season and still no snow! What the heck, I thought this was supposed to be another La Nina year?! Last winter Boise Idaho had a huge snow storm right before Thanksgiving, which drove a lot of the early season trends in wintering raptors counted. This season has been a bit different so far with certain species sticking around in higher numbers taking advantage of the little to no snow cover. I have already counted nearly as many American Kestrels, Red-Tailed Hawks, and Ferruginous Hawks as I did all of last winter, and we still have two and a half months to go.
While there has been no snow, it certainly has been cold enough with temperatures rarely making it out of the 30s the last few weeks, making for crisp and clear survey conditions: Perfect! Here are my raw count totals from November 15 through December 15, 2011 inside the Morley Nelson Snake River Birds of Prey National Conservation Area:
Figure 1. Raw raptor species totals through December 15, 2011 in the Morley Nelson Snake River Birds of Prey National Conservation Area. Northern Shrikes are considered an "honorary raptor" in my book.
Things are just starting to get going, and it seems after a slow start the Rough-Legged Hawks are finally here is full swing. There have also been 4-5 Snowy Owl sightings in southern Idaho already this winter, one in my study area seen by another biologist. These arctic breeding owls rarely make it down this far south, so it is likely their main source of food up north, Lemmings, is in the midst of a cyclic population decline. This means they need to migrate further south than normal to find food during the harsh winter months. I have yet to see one of these magnificent birds, but I am keeping my fingers crossed in the hopes that one of these days it may fly right in front of my face! In the mean time, here are a few great photos taken by a fellow biologist during road surveys conducted last week. Enjoy, and until next time, everyone have a great Holiday and New Year…
Golden Eagle. Photo by Yozora Tadehara.
Adult Male Rough-Legged Hawk. Photo by Yozora Tadehara.
Hello Wild Lens followers, sorry for the delay between blog posts but this past month has been a busy one for Wild Lens! “Scavenger Hunt” is mostly completed and we have already submitted the film to 10 festivals: waiting anxiously for replies… We are also continuing to work on our Idaho Bird Observatory piece and have conducted interviews with IBO Directors Greg Kaltenecker and Jay Carlisle. Video editing is in progress.
The Snake River Canyon in the Morley Nelson Snake River Birds of Prey National Conservation Area
In the mean time however, I thought I would take a minute to keep people up to date on the bird world. IBO’s fall migration season closed down on October 31st, and now one has to wonder: What do these birds do in the winter time? Well, there just happens to be an area south of Boise, Idaho that supports one of the more diverse and abundant wintering populations of raptors in the western United States: The Morley Nelson Snake River Birds of Prey National Conservation Area, or NCA.
Golden Eagle. Photo by Beth Orning-Tschampl
The NCA was set aside as a National Conservation Area due mainly to it’s unusually large breeding densities of Prairie Falcons and Golden Eagles, however the region also supports a large density of wintering raptors. It is here that I spent last winter surveying for wintering raptors in an effort to document population changes over the last 20 years for my Master’s Thesis at Boise State University. Some of the more common species that can be seen here in the winter are Golden Eagles, Prairie Falcons, Rough-Legged Hawks, Northern Harriers, Red-Tailed Hawks, and American Kestrels. Some less common species include Ferruginous Hawks, Merlins, and Short-Eared Owls.
Rough-Legged Hawk. Photo by Beth Orning-Tschampl
I have recently started conducting raptor surveys again this winter starting November 15th, and will continue to monitor these birds through the end of February 2012. My goal will be to update everyone monthly on the total number of each species I have seen, along with any interesting pictures or stories I may have to share about all that time I spend standing around in the freezing cold counting birds!