Winter raptor sightings in central South Dakota over the last 5 years. The Fort Pierre National Grasslands themselves used to be “the” hotspot for winter raptors, including great chances for rarities like Gyrfalcons and Snowy Owls. In recent years, raptor numbers are incredibly low compared to areas just south of the Grasslands, in and around Presho and Kennebec. Click on the map above (or any other image) for a larger view.
I still vividly remember the first time I had ever visited the Fort Pierre National Grasslands. It was 2000, and I had been bitten by the birding bug. Hard. Much of my free time was spent birding and taking photos, and as a new birder, there certainly were plenty of “new” birds to discover, just around my home town of Brandon. One of my friends at work was an avid, lifetime birder, and he not only helped with identification of the birds in my (quite poor!) early photos, but he also helped to stoke the birding fires. That was very evident when reports came in of a Gyrfalcon on the Fort Pierre National Grasslands. In the years since, the Grasslands have become known as a wonderful location for finding these very rare winter visitors, but at the time, it was something rather novel. Given that my lifetime birder friend had never seen a Gyrfalcon, I knew this was something special for a birder and I was excited to try to find it. Thus began 16 winters of making periodic birding treks to the Grasslands.
It couldn’t have been easier on that first visit. The famed “Pheasant Farm Gyrfalcon” was hanging around a farmstead that raised pheasants for hunting operations in the region. I talked with Doug B. in Pierre, a great birding contact who also helped a lot in my early birding years, and he provided directions (we’re WELL before cell phones and google maps here!). He had said that he was likely to be around that location early on a Saturday morning, so I made plans to get up ridiculously early and drive to the Fort Pierre National Grasslands and arrive at that spot just after dawn.
The ubiquitous Rough-Legged Hawk, once seemingly found on every other fence post and telephone pole on the Fort Pierre National Grasslands. However, for the last 5 years, they’ve been curiously absent.
That cold December day came, I set the alarm, packed up my equipment at 4:30, and started the 3+ hour drive. My timing was good, and I arrived on County Line Road right around 8:00 AM. As I reached an old abandoned schoolhouse that marked the location close to the pheasant farm, I saw a pair of cars. I got out, saw Doug B., and asked if they’d seen the Gyrfalcon. He smiled, and pointed to the top of a nearby telephone pole, and there it was! My first Gyrfalcon, about as easy a “capture” as a birder can ever hope for with such a rarity!
From that day forward, I was hooked on the Grasslands. Given that it’s about 3 1/2 hours from home, it’s not a love of convenience! But I quickly learned to appreciate the isolation and beauty of the area. Most days on the Grasslands, you run into very few people, and there are times after a nice wet period where the beauty of the grasslands and flowers can be really spectacular. But of course, it’s the birding that was the main attractant for me, and my GOODNESS what incredible birding there was. Winter in the middle of South Dakota may not sound like a time for vibrant bird life, but the Fort Pierre National Grasslands was building a reputation as a magnet for raptors. This not only included one of the best chances in all of the lower 48 states to see a Gyrfalcon, but also a diverse list of other raptors that spent their winter months on the Grasslands. Rough-legged Hawks were found in extremely high numbers, such that many times it was quite rare to drive more than half a mile on County Line Road and NOT see a Rough-legged Hawk hanging out on a telephone pole or fence post. It’s the first place I saw a massive, incredibly powerful Golden Eagle. It’s the place where I first saw a Ferruginous Hawk, a bird with such a brilliantly white underside that from a distance I thought I was about to see my first Snowy Owl. It wasn’t that year, but later the Fort Pierre National Grasslands WERE the place I saw my first Snowy Owl, including one incredible year where Snowy Owls were practically as abundant as the ever-present Rough-legged Hawks. It’s the first place I saw a Prairie Falcon, a bird that for a long time was a photographic nemesis for me given their predilection for flushing and flying away whenever I got within 1/4 of a mile of one. It’s the first place I saw a Short-eared Owl, a summer-time encounter where two adults were tending 4 younger birds. That encounter concluded with an adult circling me for several minutes as I stood outside my car, resulting in one of my most memorable photo opportunities (and a new Canon DSLR camera body, thanks to the photo winning a nationwide Canon photo contest!).
Winter sightings of just Rough-legged Hawks. Note the incredibly dense populations near I-90, and the sharp drop off towards the Grasslands in the north.
There have been days on the Grasslands where a full, complete day of birding could simply consist of driving back-and-forth on County Line Road and occasionally taking one of the small gravel roads that connect to it. One could potentially stay within a relatively small driving area of 10 to 20 square miles, and find dozens, upon dozens, upon dozens of raptors. Since that first day in 2000, I’ve had some of my most memorable photo experiences on the Fort Pierre National Grasslands in winter, including finally getting a close shot of a Prairie Falcon, having a curious first-year Gyrfalcon circle me in curiosity in much the same way that Short-eared Owl did years before, capturing a photo of the massive wingspan of a Golden Eagle as it takes flight, and finally capturing my first decent photos of a Snowy Owl. During all my winter trips to the Fort Pierre National Grasslands, I learned to appreciate not only the Grasslands themselves, but the area south of the Grasslands. I’d necessarily drive the I-90 corridor past Reliance, Kennebec, and Presho to get to the Grasslands themselves, and couldn’t help notice all the raptors in the area. Soon, my “Grasslands” birding trips became “central South Dakota” birding trips, with days where I’d usually spend mornings in the Presho area and afternoons on the Fort Pierre National Grasslands. Birding life was good, and many a cold, dismal, South Dakota winter was saved by the vibrant display of life that was always available on the Grasslands.
And then…something happened. It started about 5 years ago, when I planned one of my “usual” winter trips to the area. The first half of the trip was the same as always…plenty of raptors of all kinds in the Presho area, and plenty of photo opportunities. However, as I headed north towards the Grasslands themselves, the birds disappeared. Given my past history of finding winter raptors on the Grasslands, I kept expecting the birds to show up around the next corner, but…they never did. There was an occasional raptor here or there, primarily Golden Eagles or Ferruginous Hawks, but the incredible density of Rough-legged Hawks, the species that once made up a good 80% of all the raptors found on the Grasslands, was simply absent. Almost TOTALLY absent.
A Greater Prairie Chicken on the Fort Pierre National Grasslands. Whatever the cause of the raptor decline on the Grasslands, it doesn’t appear to be because there’s been a noticeable decline of gamebirds.
That first winter after the raptors disappeared, I just speculated that something happened to the prey base that attracted the raptors. When driving the Grasslands, you always saw plenty of Ring-necked Pheasants, Greater Prairie Chickens, and Sharp-tailed Grouse. There were several times where I’d sat in awe as a Gyrfalcon dive-bombed pheasants in search of a meal, and clearly the gamebirds in the area were one thing that attracted raptors. There didn’t seem to be any obvious crash in the populations of these three gamebird species. The famed Pheasant Farm near County Line Road had stopped raising pheasants, but that’s such a local phenomenon that it couldn’t explain the drop in raptors across all the grasslands. Indeed, this winter I visited the Grasslands a couple of days after Christmas, when a massive storm had coated the region in snow and crusty ice. I ran across truly massive groups of Sharp-tailed Grouse and Greater Prairie Chickens, milling about in the open and looking for foraging spots in the ice-locked vegetation. Yet despite all the gamebirds that were out, raptors were again curiously absent. I didn’t spot a single Rough-legged Hawk on the Grasslands themselves, despite easily finding over 30 earlier in the day down by Presho.
If not a decline in gamebirds, what else? One factor that may play some role is the loss of some truly massive prairie dog towns in the region. On County Line Road itself, there have always been a few locations for prairie dogs. Not all raptors target prairie dogs, but Ferruginous Hawks certainly key in on prairie dogs, and prairie dog towns. Over the last several years, many of the prairie dog towns in the area have disappeared. Those outside of the administrative boundaries of the Fort Pierre National Grasslands themselves are fair game for poisoning, to clear the land of these “pests” (don’t get me started). The largest prairie dog town I knew of in the area was on the east end of County Line Road, just outside of the Fort Pierre National Grasslands itself. It stretched for almost a mile on the north side of the road, with more scattered spots on the south side of the road. A few years ago, that entire area was clearly poisoned, and the massive colony is gone.
However, the decline in prairie dogs also fails to fully explain the decline in raptors. There are NO prairie dog towns down by Presho and Kennebec, yet raptors of every kind are still found there in incredible numbers. Perhaps it’s a decline in the small rodent population in the area? For a raptor such as a Rough-legged Hawk, mice and voles make up a huge part of the diet. Could there have been some cyclic decline in small rodent numbers on the grasslands? That was my initial thought, but it’s been 5 years since the noticeable and sharp decline in raptor numbers. You wouldn’t think some repetitive cycle of boom-and-bust rodent populations would be in “bust” mode for so long. Perhaps it’s related to the Prairie Dog poisoning? Could that have also had an impact on small rodents in the area?
A Black-tailed Prairie Dog. There’s little doubt number of these guys HAVE declined around the fringes of the Grasslands, given active poisoning programs.
One other major prey source in the area, particularly for Merlins and Prairie Falcons, are the sometimes huge flocks of Lapland Longspurs, Horned Larks, and Snow Buntings that are found in the area in the winter. The vast majority of Merlin sightings I’ve had in South Dakota have been on the Grasslands themselves or in the Presho area. During my last trip over Christmas, the first raptor I saw at dawn was a Merlin munching on a freshly caught Horned Lark by Kennebec, and I’ve had numerous other occasions over the years where I’ve seen Merlins feeding on Horned Larks or Lapland Longspurs. You do see roving flocks of Longspurs, Larks, and Snow Buntings on the Grasslands,certainly enough to capture the attention of a raptor that’s passing through, but the numbers of those potential prey species have seemed higher in the Presho/Kennebec area in recent years.
The maps that are shown in this post are indicative of the raptor numbers on the Fort Pierre National Grasslands vs. the I-90 corridor in recent years. These are all actual sightings made by myself over the last 5 years, and recorded in eBird. During each and every trip I’ve made in the last 5 years, I take the same general routes. I start in the Kennebec/Presho area around dawn, by mid-morning start to work my way up through the Grasslands themselves, and then start to head back down south again by mid-afternoon. It’s clearly not a precise, spatially distributed sample of the space shown on the map, but over the last 5 years, I have driven most of the roads in a rectangle bounded by Highways 1806 and 273 on the east, an area typically no more than 5-8 miles south of I-90 south of Presho, and Kennebec, westward to Highway 83 and a few miles to the west (particularly around the Sheriff Dam and Richland Wildlife Area, and northward to County-Line Road itself and a few miles north of it. Good roads are few and far between in parts of the area, particularly north-south roads that take you from Presho northward into the Grasslands. As a result, the maps here tend to show the 2 major north-south gravel road that connect the two areas, as well as other more easily traveled roads in the area.
A Gyrfalcon taken during the “Golden Years” on the Fort Pierre National Grasslands. This is a very dark-phase juvenile, and I’ve never seen one quite like this. The Grasslands may still be a good spot to try to find this mega-rarity, but it’s not an ideal spot for other winter raptors any more.
I wish I had eBird recordings for the “golden years” on the Grasslands, prior to this last 5 year period, something against which these maps could be compared. I DO have a vast number of raptor photos taken on the Grasslands themselves from 2000 to present, with most of those from 2011 and earlier. What’s clear from these maps, however, is just how sharp a delineation there is between the I-90 corridor, and raptor numbers to the north on the Fort Pierre National Grasslands themselves. On the map at the top that shows all raptor sightings I’ve recorded, note the one north-south road that extends up from the I-90 corridor, about halfway between Presho and Vivian. That’s my main path for getting north, and while there are plenty of raptor sightings south of the Grasslands, those sightings drop off sharply almost exactly at the Grassland boundary itself. On EVERY trip over the last 5 years, I will drive County line Road, an east-west road along the county boundary (visible towards the north side of these maps). Once THE hotspot for raptors, in the last 5 years, I have very few raptor sightings of any kind along this road. Rough-legged Hawk sightings on the Grasslands are incredibly small when compared to the area just to the south of the Grasslands. Red-tailed Hawks and Northern Harriers have always seemed to be much more abundant in the southern part of this area, but in recent years they are almost completely absent once you get 4 or 5 miles north of I-90. Bald Eagles are often incredibly abundant in and around the Presho area. I have had days where a dozen or more Bald Eagles are sitting in one concentrated area, and there are also at least 3 active Bald Eagle nests that I’ve found in and around the Presho and Kennebec area. I have a few Bald Eagle sightings around the Grasslands, but that’s certainly dwarfed by how many have been found in and around Presho.
There are some species that are more evenly distributed in the area. Golden Eagles are a species I’m almost certain to find on any trip to the area, and it doesn’t seem to matter whether I’m on the Grasslands, or in the Presho/Kennebec area. Prairie Falcons also seem rather randomly distributed, as they seem rather unpredictable and likely to pop up just about anywhere on this map. Ferruginous Hawks also seem rather even distributed. Is there something in common about these species that may make them more likely to be found on the grasslands? Golden Eagles and Ferruginous Hawks are much more likely to key in on mammals, including rabbits and other larger mammals. Perhaps if it is a population crash of small rodents, they’re still on the Grasslands as they don’t depend on those smaller prey as much as Rough-legged Hawks or other raptors. Prairie Falcons can feed on a variety of prey items, including small birds like Horned Larks, and even large birds like Greater Prairie Chickens. Perhaps they too would be less sensitive to a decline in small rodent numbers.
I’ll continue to make my winter treks to the central part of the state, including visits to the Grasslands. Given that the Grasslands themselves are still the location where I’ve seen most of my Gyrfalcons over the years (including the years prior to the data represented in these maps), that alone is clearly worth the time! Hopefully over the next few years the Grasslands recover from whatever “ails” it in terms of supporting winter raptor numbers.