Roost Ring Creators

[Fred Kaluza~MI]

Has anyone physically gone to the apparent center of a roost ring and seen birds other than Martins? Since RADAR was invented, these "mysterious" rings have been seen and have turned out to correllate to groups of rising birds around sun-up. In Michigan at least, several rings appear each morning but we just can't believe they are Martins. Has anyone, anywhere gone to look for a "Martin" roost and found they were really Starlings or Common Grackles or even Red Winged Blackbirds or any far more common group of birds? The contention is that SOME rings in SOME places are Martins but not ALL are. I suppose the intent of this latest PMCA project is to determine just that but somewhere over the last 60 years, hasn't the answer to this question been determined before?

[CUL Lou~Mich]

Fred. This is just my opinion. I doubt that anyone has went out and verified these things. First off, I've been on the puter for around seven years. I've only heard of these rings the past two. Prior to that, no one knew about them. I'd think in order for someone to have known about them, they'd have had to be working for the weather service, watching on the weather service machinery. Otherwise how would they get to see the returns? If they were working for the weather service, I doubt they would have had time to be out looking for the rings, or birds in those numbers. Besides, the weather service folks would have been more interested in weather related stuff that they had been watching for hours, coming from afar. Granted, I could be wrong, and I'll be the first to admit this. However, given the newness of seeing these rings, coupled with the newness of anyone being able to put pictures of them onto the computer, plus the newness of computers, I sincerely doubt it. I just think the "Roost Rings" and the knowledge of them is simply too new. CUL Lou

[Fred Kaluza~MI]

Well, at least some people were aware of what these things are in the academic community as far back as 1958.

http://adsabs.harvard.edu/cgi-bin/nph-b ... ML&format=

Here's another...

http://www.uwsp.edu/cnr/faculty/russell ... 0Radar.htm

I think maybe Mark Dietrich is right. around here they are more likely to be Starlings than Martins. Uggh!

[Al Denton]

Fred, I have gone out twice to check rings and found nothing. Talk about a wild goose chase I have also been to an actual roost that was never spotted on radar(roughly 5,000 martins) I even had the weather man here checking his stuff and found nothing on his screens though the roost was real. I also would not doubt that some rings are starlings or others. I've seen large roosts of starlings to remain in one stop for only a day or two. That could explain a lot. I'm not sure what these rings are telling us. Al

[CUL Lou~Mich]

Fred. Okay, I stand corrected. However, it'd be pretty interesting to know if any of the "Academic community" went out to check and see if they were Purple Martins, Starlings, or whatever, or if they could even find the origination of the rings. I believe the second example was dated 1998. Again, there is no mention of actually verifying what they were by visually seeing the birds. CUL Lou

[Fred Kaluza~MI]

Lou, I'm not being a jerk, but the very first line of the abstract states..."An account is given of the radar ring angel phenomenon; observations are described which prove that these rings are produced by the dispersal of starlings (Sturnus vulgaris) from their roost at sunrise."

They then go on to quote a whole bunch of measured dispersal flight speeds and the measured time between "waves" of launching birds. It appears to have been a very well thought out study. If there is any way to discern what species dominate within each ring, it's going to be in the analyzation of the dispersal altitudes and airspeeds etc. If we can get enough detail to generate a true "signature" for each species we will really be on to something. Hey, we can tell one ship from another "even of the same class" by matching their acoustic SONAR fingerprints and they do the same with determining aircraft types by counting the number of fan blades inside a jet engine's turbines by the RADAR reflections.

There you go, granted these are native Starlings in their native environs but I also read from a link Mark Dietrich sent me that Starlings were seen to exhibit similar roosting behavior soon after their arrival in the U.S. I'm convinced that Martins are not the only bird species making these rings. As to what they are in any given location, I think they would be generally proportional to the overall abundance of the available species locally. ie...in Michigan, they probly ain't Martins! Al, it's interesting that the Martin roost you witnessed was not visible on the local NEXRAD system. I'm sure your weatherperson knew this but at the low angle of these beams (typically .5 degrees above the horizon at the emitter), it's quite possible your roost was "below the RADAR horizon" and by the time the birds were high enough to "see", 5000 may have not been enough to get a good reflection. That may be another factor in hilly terrain, Martins eat bugs, bugs like water and water tends to collect in low places. Low places equal "under the RADAR". Just an observation...Fred

[CUL Lou~Mich]

Fred. I know you weren't trying to be a jerk or anything like that. I was just stating my position, and thoughts on the whole thing. I'm sure here in Michigan it would probably be Starlings, or some other bird, since I don't believe the whole of Michigan could muster up 100,000 PMs like some folks report at roosts down South. Shucks if it weren't for having seen Mary's colony, I'd have thought we would be doing good to muster up 500. ha ha. Knowing about her colony, and a few others, I do have some hope, but it sure isn't running rampant. CUL Lou

[Daryl Lindstrom - MN]

Good discussion.... It's a good thing to question new information instead of just accepting it as fact.

I'm highly skeptical that these "rings" are actually starlings or grackles....these birds simply don't fly as high as purple martins. For the radar to pick up on a large flock of birds they need to be at a substantial altitude. Martins fly much higher than most birds that flock together in large groups. Martins also glide in circles and continue to fly for long periods of time. Other flocking birds, like starlings, don't stay in the sky for extended periods like purple martins, they land in large trees or on the ground. I have a hard time picturing starlings, redwing blackbirds, or any other birds flying in a large circle for an extended period of time at a high altitude like purple martins.

[Laverne]

I agree Daryl. This is an interesting discussion. A few weeks ago, we were wondering if migrating shore birds might create the same annulus ring as Purple Martins. However, someone else had visually detected PMs in the area of the suspected roost. So, it was left at that. I don't know if anyone ever made the effort to "be there" at the time of the evening roost formation.

I'm highly skeptical that these "rings" are actually starlings or grackles....these birds simply don't fly as high as purple martins. For the radar to pick up on a large flock of birds they need to be at a substantial altitude. Martins fly much higher than most birds that flock together in large groups. Martins also glide in circles and continue to fly for long periods of time. Other flocking birds, like starlings, don't stay in the sky for extended periods like purple martins, they land in large trees or on the ground. I have a hard time picturing starlings, redwing blackbirds, or any other birds flying in a large circle for an extended period of time at a high altitude like purple martins.

I have witnessed Grackle roosts here in SE Texas. They can be very large and the Grackles exhibit the same basic "crowding in the trees" behavior as Purple Martins. I have, also, witnessed the huge flocks of Grackles flying over in the early morning light. It has been my belief that a Grackle roost could appear the same as a Purple Martin roost on radar. But, I don't know enough about radar to have considered the "under the radar" habits of both Grackles and Starlings. They do fly much lower than Purple Martins. I think you may have hit on an important behavior of these different species that could prove "most" radar annulus rings to truly be Purple Martin roosts. That is exciting.

The one problem for me when attempting to locate "present" roost sites from radar annulus rings has been the time frame. They only occur upon dispersal in the mornings and I can't sit at the computer and watch for them in my area at that time. I know that the PMCA used recordings from 2004 to create their Project MartinRoost. Is there any way to record these current radar loop sequences and then go back and look over them when it is convenient? This would eliminate the chance of "old data" spoiling our efforts to zero in on any specific suspected roost.

[Fred Kaluza~MI]

Laverne, I agree about the collection of the sequenced images being problematic. The time frame plus the methods presently required by me are a pain. Now, I've been to my local weather office located in White Lake Township a few years back and met the station manager who gave me a nice tour of his facility. The NEXRAD system was new at the time. I was seeking atmospheric weather related data that I was convinced was affecting the quality of our Cellular Telephone System. We collect call quality metrics from bizzillions of daily call events and the measured parameters ebb and flow to the rhythms of mysterious influences. The annual emergence of foliage has an "absorbing" affect at certain radio frequencies among other things. At any rate, the station manager did have volumes of old recorded paper logs but for ready analysis I would have had to convert all the info to a spreadsheet. Basically we are not staffed to allow for me to persue my little science project. The point is that he really pushed me to a central repository, that being the N.W.S. archives. As I mentioned, I'm not sure how or if NEXRAD imagery is saved. For reasons of national security, the military has it's own systems in place and we could argue that any other existing radar networks could be used to augment or supply corroborating data as in U.F.O. detection projects or whatever. Obviously a new image is available from Doppler with each sweep of the antenna. Digital storage media gets cheaper each year and the ability process and save each sweep gets more feasible by the day. I just can't say if it's already being done or not. Obviously, the PMCA was able to acquire the images for analysys but this could have been less than a comprehensive effort, simply employing screen captures as I have done. Sounds like it's time to do more digging. I'll start by contacting my local weather office as well as a local TV weatherman I know. Additionally perhaps Pat Kramer may share his methods with us. Fred

[Pat Kramer]

The Project MartinRoost website is providing the locations of all suspected roosts found with radar in 2004 (stress "suspected"). Of course we do not know if Purple Martins are the sole species causing these radar signatures.

The PMCA is interested in learning about any attempt to locate a roost (found and unfound) as this will eventually lead to a better understanding of what causes these roost rings. Thank you to anyone who has spent a night looking for a roost in their areas! I understand how difficult it typically is. Just please keep in mind that the radar-located coordinates provided on this website are approximate locations, not precise ones. Unless the roost has been found by someone on the ground, assume that there may or may not be a roost within approximately 10-15 miles of that location.

With that said, here are some scientific papers that have largely guided Project MartinRoost.

This was taken from http://elibrary.unm.edu/sora/JFO/v069n0 ... -p0325.pdf

Although we did not confirm that Purple Martins were responsible for each of the roost sites documented in this study, severalines of evidence suggest that martins were primarily, if not solely responsible for the annular signatures we observed. In earlier work, WSR-88D radar was used to describe the spatial and temporal dynamics of martin roosts at Lake Murray, South Carolina and Lake Russell, Georgia (Russell and Gauthreaux 1998) and to confirm the presence of martins roosting at Lake Pontchartrain, Louisiana (Gauthreaux, unpubl. data). The three sites were evident during this study (Fig. 2), and all newly identified roosts exhibited identical annular patterns and temporal (e.g., daily and seasonal) dynamics. It is possible that bird species other than Purple Martin were responsible for the observed radar patterns, or that roosts consisted of mixed-species flocks with P. subis (e.g., Caccamise and Fischl 1985). Red-winged Blackbirds (Agelaius phoeniceus) and European Starlings (Sturnus vulgaris) also form annular patterns on radar during roost departures (Eastwood et al. 1962, Ligda 1958, Richardson and Haight 1970). Further, Purple Martins are known to associate in mixed-species roosting flocks with blackbirds, starlings, and Common Grackles (Quiscalus quiscula) during July and August (Caccamise and Fischl 1985). However, starlings do not depart from roosts in a constant stream, but as a series of exoduses which begin at intervals of 3 min (Eastwood et al. 1962, Feare 1995). These departures create a series of concentric rings on radar (Eastwood et al. 1962, Richardson and Haight 1970), in contrast with the single annulus formed by exoduses of Purple Martins (Russell and Gauthreaux 1998). Finally, peak roosting populations of blackbirds, starlings, and grackles occur from late summer through winter (Caccamise et al. 1983, Caccamise and Fischl 1985, Meanley 1965, Summers and Feare 1995), after most, if not all martins have departed for South America (Allen and Nice 1952, Russell 1996).

More reading:
http://elibrary.unm.edu/sora/Wilson/v11 ... -p0362.pdf
http://www.erh.noaa.gov/bgm/birds/birds.html
http://elibrary.unm.edu/sora/JFO/v054n0 ... -p0041.pdf

[Fred Kaluza~MI]

Good stuff. Thanks Pat!