Broadwing Musings

Subj: [Va-bird] Raptor populations and migratory paths Date: Wednesday, September 19, 2007 10:02:14 AM From: brenda@birdsofvirginia.com To: va-bird@listserve.com, shenvalbirds@yahoogroups.com

It is a documented fact that in our part of the Piedmont here in Virginia, the majority of Broad-winged Hawks and other raptor species will follow along and over north to south ridges during fall migration. For a number of years Bill Minor, John Irvine, Jr., Paul Saunier and others conducted a linear study in the Piedmont that included Rockfish Gap and in each and every year the majority of the birds were concentrated along and over the north to south ridges at and to the north and south of Rockfish Gap and not spread out over the valleys to the east and west. Here in our section of the Piedmont, it is MY belief that when winds are light to moderate and out of the east, the majority of Broad-wings up the pipeline following along the ridges heading toward Rockfish Gap will steer more along a narrow strip of ridges that run southward toward Charlottesville, ESE of Rockfish Gap, and they will either make a wide swing and veer SW to pick up the Blue Ridge directly south of Rockfish Gap or continue southward to Lynchburg area. The data collected by Gene Sattler at Candler Mountain located along the southeast edge of Lynchburg, approximately 45 miles SSE of Rockfish Gap and 32 miles East of Harvey's Knob, would appear to support this theory. On days when winds are light and out of the east, numbers drop significantly at Rockfish Gap UNLESS we are fortunate to catch them streaming and/or kettling far off to the east out over the Piedmont. Oftentimes a spotting scope is required to get a sufficient visual for counting purposes. Data collected at participating hawk watch sites is an important component of migration study especially now with the increasing threat of wind turbine development on top of the ridges along the eastern flyway. It it critical that migration patterns along our mountain ridges continue to be monitored, not only for raptors but bats and other avian species. As to population indicators for certain species such as Broad-winged Hawk wherein the bulk of the population migrates into South America, I would recommend individuals check totals collected at Corpus Christi, Texas and Veracruz, Mexico which provides a better picture of year-to-year population trends. Collected data by participating hawk watches is readily available by going to www.hawkcount.org. One additional note: Yesterday morning at Rockfish Gap, shortly after dawn, there was a "massive" liftoff of Broad-winged Hawk along the western slopes near Waynesboro and to the east along the base. These birds were very close to the ridge and could very well have been some of the birds that flew over Harvey's Knob to our south. The wind was light to moderate out of the NW to N. I later received reports that the wind shifted to variable and east with significant drop in migrating raptors over Rockfish Gap later in the day. Based on reports by Condon and others, it appears the Broad-wing steered along that narrow eastern ridge to head southward over Charlottesville area. Another report has come in that there may have been another late afternoon push of birds over Rockfish Gap. Shift in the winds? Totals to follow.


Subj: RE: [Va-bird] Raptor populations and migratory paths Date: Wednesday, September 19, 2007 7:32:16 PM From: MARLENECONDON@aol.com To: va-bird@listserve.com cc: shenvalbirds@yahoogroups.com

Two comments in regard to this statement posted earlier today: "It is a documented fact that in our part of the Piedmont here in Virginia, the majority of Broad-winged Hawks and other raptor species will follow along and over north to south ridges during fall migration. For a number of years Bill Minor, John Irvine, Jr., Paul Saunier and others conducted a linear study in the Piedmont that included Rockfish Gap and in each and every year the majority of the birds were concentrated along and over the north to south ridges at and to the north and south of Rockfish Gap and not spread out over the valleys to the east and west." (1) Conducting a one-day linear study each year for a few years in a row does not scientifically prove that Broadwings are concentrated along the mountains. It only proves that they were flying along the mountains on that particular day (if, indeed, they were). A linear study would need to be conducted on MANY days in September and for more than a few years, especially on a big day at the mountains, in order to make a definitive statement regarding where Broadwings migrate through this area. I personally know that on many of the high-count days at Afton, there were also big numbers of Broadwings spread out on both sides of the Blue Ridge. I am not familiar with any study that has truly proved that "the majority of Broad-winged Hawks and other raptor species will follow along and over north to south ridges during fall migration." Unless people are down in the valleys to count when hawks are known to be going over Rockfish Gap, you just can't make such a statement. This isn't to say that more hawks aren't counted on mountain tops--it makes sense that they would be because that's where people are looking for them! And, of course, the elevation assists people in spotting them because you may be closer to the birds and with more eyes scanning the skies together, the higher the likelihood of spotting birds that could otherwise be missed. (2) From the September 16 report of this year in which over 6000 Broadwings were counted : "At times, large kettles would flicker in and out in the distance and only with spotting scopes could counters get a clear visual on swirling masses, with hundreds kettling and then streaming out. One impressive flight was over 1,000 that formed several large kettles." Sure sounds like a fair percentage of Broadwings were over the Piedmont rather than above or along the ridges!
Sincerely, Marlene


Subj: Re: Fwd: [Va-bird] 2000+ Broad-wingeds at Warrenton, Fauquier 19 September Date: Saturday, September 29, 2007 7:38:47 PM From: doubtindave@comcast.net To: MikeLPurdy@aol.com --------------

Dave Holt 's reply: The author of this letter could not have been more correct. Broad-winged hawks indeed migrate on a broad front throughout all regions of the eastern United States. A very broad front at most sites but there are a few where the migratory flight is concentrated. The area around Detroit, Hawk Ridge, and Montclair N.J. are sites that come to mind. Sites where natural barriers such as large expanses of water cause the hawks to converge over small areas of terrain over which they prefer to migrate. And other sites along the Atlantic Coast such as Cape May and Kiptopeke. Would that there was a concentrated watch on the outer banks of North Carolina. Alas! Now all of us hawkwatchers who are bound to our sites inland along mountain ridges and maybe in the Piedmont regions are not making any contribution whatsoever to the monitoring of hawk populations. If anything comes from our hobby it is maybe the study of the behavior of hawks in migration. The only scientifically legitimate place for monitoring the population of migrating hawks is in the Isthmus of Panama. Back in the 1970s Dr. Neal Smith spent ten years trying to count them there and found it impossible to do so. Over the thirty years or so that I have been hawkwatching and scanning the data from other sites I have concluded that massive (in the thousands) counts of hawks can be seen from anywhere during the migration season. I have also been satisfied that my hawkwatching efforts have nothing to do with monitoring the populations of hawks and has no contribution to the preservation of hawks. Thousands of people in that enterprise came to the conclusion that the Osprey and Bald Eagle no longer needed protection long before my puny efforts on the hawkwatch came to the same conclusion. But, I still enjoy hawkwatching as it provides me with a question to answer: Why was the hawk I saw in my view in the first place? I am examining, at best, a patch of sky that has a two mile radius. That is an extremely small sampling area when one considers that the hawk one has seen could be anywhere in a billion mile radius. When I have dutifully attended a mountaintop site in the hope of finding thousands of hawks only to be advised by another watcher who was to attend the site that day that he counted 3000 hawks from his home while loading the car to attend the site, I began to wonder why attend the mountaintop site indeed. It is all about that question of : Why was that hawk in my view in the first place? One must place oneself in a place where one can see the most hawks and in our region it is on a ridge top or some hill in the Piedmont that affords one with a near 360 degree view. And it must be a place where we can easily attend as many days as possible during the migration season. Then we must collect and store three aspects of data: weather, hawks, and topography. One of these aspects appears to be a constant and that would be the topography but that can change also. A new clear cut in the nearby forest would have an effect on the thermal density within the purview of the site. So the data collected must be strict and comprehensive. Weather, hawks, and topography strictly recorded will answer the question of "Why was that hawk in my view in the first place?" Anything else is simply scorekeeping among sporting birders . Dave Holt >


Subj: Re: Fwd: [Va-bird] Raptor populations and migratory paths Date: Saturday, September 29, 2007 8:00:42 PM From: doubtindave@comcast.net To: MikeLPurdy@aol.com --------------

Dave Holt replies: I was privy to the linear studies that John Irvine conducted in the vicinity of Rockfish Gap and I saw no control evidence of searching the Valley or Piedmont areas alongside of the Rockfish Gap site during those linear studies. There are plenty of documented sitings from valley and piedmont of massive movements of Broadwings over many of the years that the Rockfish Gap and Harvey's Knob sites were manned. I highlighted the June Crutchfield / Alice Davis finding of 3500 hawks from a point off the east side of the ridge at Rockfish Gap well within the Piedmont when the Rockfish Gap site was clouded in which it often is. Myriam Moore once reported that counting 3000+ Broadwings prevented her from leaving home to attend the watch when no hawks were seen on the mountaintop site at Harvey's Knob. I personally have seen massive Broadwing flights over the city of Roanoke while there were massive flights over Harvey's Knob. And in the past ten years or so there have been several massive flights over Candlers Mountain near Lynchburg that have surpassed the flights over Harvey's Knob. The only time that the Broadwinged flights stick to the ridges is when the prevailing winds are in a ridge crossing direction, either NW or SE . Otherwise the hawks are soaring on thermals and their only direction is southward and the ridges be damned. Dave Holt 9/29/07


Subj: Re: Fwd: [Va-bird] hawks going by to the East Date: Saturday, September 29, 2007 8:46:11 PM From: doubtindave@comcast.net To: MikeLPurdy@aol.com -------------- Original message

Marlene Condon has hit the nail on the head. She asks what value our counts can be to researchers? Absolutely none. No professional researcher would touch our data as it isn't in the least gathered in a professional manner. The counts themselves are fairly accurate I believe but the conditions under which the counts are gathered leave much to be desired. Wind speed and direction are extremely important but most observers only pay attention at the turn of the hour. Visibility is important but there is no standard by which everyone can agree. Cloud cover is useless without knowing the cloud types. We are simply playing games with other sites by keeping score. We get burned and we wonder why but we make no effort to find out why we get burned. We fail to answer the most pertinent question: Why was that hawk in my view in the first place? After all, I am only examining a two mile patch of sky. Am I really interested in why I am seeing the hawk or am I just interested in scorekeeping versus some other site? Dave Holt


Subj: Hawk migration musings Date: Saturday, September 29, 2007 9:23:46 PM From: doubtindave@comcast.net To: MikeLPurdy@aol.com

I am not interested in arguing with birders at large. But I am interested in letting those who are interested know where I stand. The data has to be maintained locally at each site. HMANA does not analyze the data. It never has and it never will as the analysis of the data is not its mission. Its mission is simply to collect and store the data. The so-called HMANA Journal is merely a score keeping publication. Any analysis in the Journal is simply what the local site personnel come up with about the seasons records. The data from each site is stored in file cabinets at the Hawk Mountain Sanctuary to be released to any legitimate researcher who requests it. As you know any researcher would be pressed by time. Would he or she be willing to sacrifice time to look at the data at an obscure site on the Blue Ridge called Harvey's Knob? A site where no one can agree on the cloud cover, visibility, wind speed, or wind direction. I don't think so. We are quite capable of answering the question: Why was that hawk in my view in the first place? At least at Harvey's Knob we are capable of answering that question. We have the data to do so and the inquisitiveness to do so. Dave Holt


Subj: Re: [Va-bird] Raptor populations and migratory paths Date: Sunday, September 30, 2007 12:06:34 PM From: MARLENECONDON To: MikeLPurdy

Gosh Mike, I can't tell you how very much this correspondence means to me. I have more than once seen many thousands of Broadwings in the Piedmont as well as in the Valley. I would report them to the Rockfish Gap hawkwatch site and no one ever bothered to add them to the count. This mystified me since I thought the point was to document how many were migrating, not "prove" that they only go in large numbers over the mountain sites. Thank you so much and please thank Dave Holt as well. I deeply appreciate the time that both of you have taken to answer my musings on the list-serve. Ever so gratefully, Marlene


Subj: Re: Fwd: [Va-bird] Raptor populations and migratory paths Date: Monday, October 1, 2007 6:34:54 PM From: doubtindave@comcast.net To: MikeLPurdy@aol.com -------------- Original message ---------------------- From: MikeLPurdy@aol.com > Hey Dave, > > I got this note from Marlene after I forwarded your reply regarding one of > her posts. > > Mike > >

Dear Mike, Marlene was victimized by John Irvine's notions about hawk migration. I was privy to his so-called linear study and I found that it had no value whatsoever and I think that Marlene suspected the same thing. I was glad to find a comrade in Marlene. Back in the late nineties I submitted a theory about hawkwatching to Myriam Moore. That theory tried to explain why the Harvey's Knob Hawkwatch bested the Rockfish Gap Hawkwatch for the first and only time in twenty years of concurrent coverage of the Broadwing flights. Myriam sent my suggestion to John Irvine and he proceded to criticize it in his publications for the Rockfish Gap Hawkwatch. When I offered rebuttals he dug up some part time hawkwatchers to rebut my rebuttals and so on ad infinitum. I grew weary of shooting down his rebuttals and even discussing the subject with him. It was at that time that I decided to quit HMANA, the VSO, and the RVBC. Hawkwatching requires people who are receptive to new ideas and who seek new frontiers to explain the phenomena that is taking place before our very eyes while on watch. I am absolutely convinced that there is a meteorological/topographical reason for each and every hawkwatching site to observe migrating hawks and that each and every site is limited by its meteorological/topographical orientation. If you are truly interested I will submit that theory and maybe more. Do with this whatever you please. Dave Holt

Subj: Re: [Va-bird] Raptor populations and migratory paths Date: Thursday, October 4, 2007 9:33:23 PM From: doubtindave@comcast.net To: MikeLPurdy@aol.com -------------- Original message ---------------------- From: MikeLPurdy@aol.com > In a message dated 10/1/2007 9:59:32 PM Eastern Daylight Time, > doubtindave@comcast.net writes: > > the 2007 counts at HK has far exceeded the 1995 counts and I do not know what > the prevaling winds were this year. > I think most of the big Broadwing days this year were on easterly winds, if > I'm not mistaken. We were discussing that if not for the East winds Candler Mt. > would probably have gotten the larger numbers. The biggest flights of BWs on > the Tuesday with 4,000+ were pretty much directly overhead, or slightly east > of the ridge, if I remember correctly. It was pretty awesome. It seemed like > Broadwings were coming thru all day. One of the Hollins Univ. groups came up > and got to see over a thousand hawks. Their instructor was telling them how > lucky they were, that this had never happened to one of the Hollins groups, etc. > I > wish you had been up there. > > Mike > We just returned from a three day trip to the Poconos in PA for a visit to Joyce's brother. My general theory has no problem with hawks soaring on ridge crossing winds but my specific theory does have a problem with the numbers you scored this year at Harvey's Knob on easterly winds. They should have been there but where did they come from. More about this later, as I need to recover from a bug-eyed traffic fighting trip down I-81. But, thanks for the confirmation info. I need to look a bit deeper this year into the prevailing winds for the season and what they have been for the past ten years. Just to tickle your interest the prevailing winds from 1975 thru 1995 at Woodrum Field were SE at 9 mph. Wind speed and direction is very important. Dave

Personally, I would like to track the BWs this year from Canada to here in > relation to local weather conditions to perhaps get some idea of how they came > to the Blue Ridge in such numbers. > > bj > > A few years ago Kerrie Kirkpatrick of northern Virginia tracked high number sighting reports of Broadwings via official and anecdotal reports. It was a flight of 10,000 to 15,000 BWs maybe 20,000. She tracked them down to the southern Pennsylvania border (Mason Dixon line). The Snickers gap site had a fairly large flight at the proper time along the track but Rockfish Gap and Harvey's Knob got zilch. If it was a wave of hawks steadily progressing in a wave latitude to latitude it veered eastward. I don't remember the reason I concluded that but it was probably due to the fact that no huge flight showed up at any site south of the Snicker's Gap site. From what she found it did look like a wave, at least, in the southern PA area. But, it did not maintain the appearance of a wave after Snicker's. Southern Pa is where she received the most reports. I think I concluded that a change in weather when the birds should have shown up at the Rockfish and Harvey's Knob sites caused them to disperse. In all the years I have been hawkwatching while privy to information outside of our immediate area I never saw any indication that a wave of migrating Broadwings ever existed other than the above. My own compilations showed peak flights for one season at Washington Mounument (near Hagerstown MD) Rockfish Gap, Harvey's Knob,and Pilot Mt., NC simultaneously. That is on the same date during the same part of the day. I do not believe that there is a wave of migrating BWs that will show up north of southern Texas. You are quite right in assessing the variables but the independent variable will show up at each and every lookout to a different degree. And it will only determine the number of migrants seen not the true number of migrants. For a population monitor a huge number of sites aligned east to west situated as close as possible along a designated latitude all manned at the same time would be necessary. Add to that problem that each and every site along that line, would have to be evaluated over time as to its ability to display to the human eye the maximum number of migrants. It is that last statement that I would like to assign a weight to the Harvey's Knob site. That is probably the best the amateur hawkwatcher can contribute to the art of hawkwatching. DJ