THOUGHTS ABOUT ROOSTS & FALL MIGRATION==TX

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John Barrow
Posts: 944
Joined: Tue Nov 11, 2003 4:12 pm
Location: Corpus Christi / Sandia , Texas

Reading through recent posts there seems to be some confusion about the dynamics and timing of migratory roosts and migration timing of purple martins nesting in TX.

During the nesting season adult martins, particularly ASY males will establish a local roost in the area, often over-nighting at the location along with martins from nearby locations and returning to the home colony in the early dawn hours to resume feeding their brood. These "local" roosts will typically be located within a 10-30 mile radius, allowing timely returns to home colonies. At the same time, and as fledglings establish independence, home colonies can be observed parking new fledglings in nearby trees, training them about roost behavior. Toward the end of nesting these local roosts will grow in size, but typically not to a size emitting a strong visual radar signal. By the end of July these local roosts will consist primarily of hatch year and a small percentage of SY martins.

As the local roosts dissipate, secondary, and much larger roosts will form along the migratory path. Unlike local roosts that typically are located by local landlords out searching for them, by reports from local birders or from complaints from neighbors living near a roost. Secondary roosts begin as a conglomerate of local roosts, bolstered by birds intercepted while migrating through the area. They are also dominated by HY and younger martins, and, being much more populous, can generally be located by radar signal.

A number of these roosts are reported on PMCA's MartinRoost page and attract hundreds of human visitors. Others are listed based on a their radar signal; however, have not been seen or located--likely being on private and inaccessible property. Typically these secondary roosts will begin forming in Texas in mid July, and unless northern migrants are intercepted traveling South, these roosts will begin to dissipate around the middle of August. In the event northern birds are attracted to the roosts in large numbers, the roost might remain partially active through September, and rarely in to October.

In preparing this report I looked through notes I had submitted to PMCA's MartinRoost page from some of the roost chasing I did in Corpus Christi from 1999-2006, excluding trips I made to the Edinburg/McAllen/Harlingen, TX roost locations.

In addition, I reviewed (complete) migratory maps produced from geolocator returns for 13 ASY martins I tracked in 2013-14.

Here are some interesting observations from those maps: All of the 13 immediately left the USA flying nonstop in to Mexico and stopping for an extended period at or near the Yucatan Peninsula, except for 3--two stopping at the McAllen roost for 1 and 2 days respectively, and the third going to a roost SW of San Antonio for 4 days before leaving the country. Roughly half of the 'tagged' martins left the USA before the end of July, and all had departed the country prior to the middle of August. This fast exodus from USA has been duplicated by other geolocator/GPS returns from throughout the continent.
~~TEAMED WITH A MARTIN GODDESS~~

Member/Mentor-PMCA. I do regular nestchecks and participate in PROJECT MARTINWATCH!! Coordinated 3 geolocator studies-2009, 2010 & 2013. State and Fed licensed bander (retired Jan., 2020)
Hanover Bill
Posts: 615
Joined: Thu May 14, 2009 3:10 pm
Location: Pennsylvania/Hanover Township
Martin Colony History: 2009 & 10 - 0
2011 & 12 - Visitors
2013 - 2 pr. fledged 9
2014 - 3 pr. fledged 13
2015 - 7 pr. fledged 27
2016 - 15 pr. fledged 72

Great post John, very informative. I always wondered what they do between leaving the colony, and showing up at the large pre-migratory roost. The mini roost makes perfect sense.

Up where I am located in South Western Pa. the general consensus is that our Martins actually travel North to the large pre-migratory roost on Presque Isle, in Erie, a distance of about 100 miles, and begin the migration from there. It always seemed strange to me that they would travel North before heading South. Do you have any thoughts on that?

Hanover Bill.
2009 & 10 - 0
2011 & 12 - Visitors
2013 - 2 pr. fledged 9
2014 - 3 pr. fledged 13
2015 - 7 pr. fledged 27
2016 - 15 pr. fledged 72
Mike Mack
Posts: 42
Joined: Mon Jan 27, 2020 11:56 pm
Location: Centex

Hi John, good hearing from you and thanks for the good info on the roost migrations. Most all my martins are I guess gathered with the big roost in Round Rock about 30 miles away. Had been getting 50 to 100 visitors around midday but that slowed down just a few days ago. Now the visits are much earlier around 9 but don't last as long but for the second morning in a row pretty much had martins on every house and plenty in the air. Don't know how many are mine but a lot are very familiar with the houses.
Sky
Posts: 5
Joined: Thu Jul 16, 2020 1:55 pm
Location: Central Texas

Just wanted to say thank you SO much for taking the time to share this information! Especially welcome to newcomers like myself who have much to learn.
John Barrow
Posts: 944
Joined: Tue Nov 11, 2003 4:12 pm
Location: Corpus Christi / Sandia , Texas

Hanover Bill,
A couple of thoughts having visited the Erie roost two times. First, the Presque Isle location has been utilized as a pre-migratory roost for many years and offers an abundant food source to sustain the large roost, in addition to being a prime seasonal feeding area. It attracts martins from all directions throughout the season. I suspect there is tendency for young martins to "follow the leaders" to a specific location and the roost area is well known to the SY and ASY birds. Secondly, 100 miles is not a long way to travel in the context of migration. During the roosting event I suspect some martins feed out 50 or more miles every day in all directions. No doubt martins feeding northward from SW PA during the season are going to encounter the more numerous populations located south of Erie (Bill Wenger and the Troyer's colonies for example) as they feed the area to the south. You will note that one of my geo-tagged martins traveled for a few days to a roost near San Antonio--100 or more miles to the NE of its colony location. I suspect its motivation was some prior contact at a common feeding area with other martins using that roost location, but have no way of knowing.

The ability to track martins on a daily basis has provided a lot of insight to their behavior. It has also challenged a lot of existing theories. I am copying some of Dr. Bridget Stutchbury's comments as contained in an article published by Texas Parks and Wildlife Magazine in May, 2014. The article was written primarily about the 2009 geolocator study we coordinated in Corpus Christi, TX, but the remarks reflect the knowledge of 2014, at which time other studies had been completed in other locations around the continent. (Note: Dr. Stutchbury helped develop and pioneered the use of geolocators in tracking small songbirds, including purple martins, from Edinboro, PA in 2007)

Discovering Migration Secrets

The research brought discoveries that challenged ornithologists’ assumptions about purple martin migration. Until then, scientists assumed that the birds’ decline was due to pesticide exposure in their wintering grounds in the soybean and sugarcane fields of southern Brazil.

But Stutchbury was surprised to find that the tagged birds didn’t even go to southern Brazil. Instead, they wintered deep in the Amazon rainforest, where “America’s backyard bird” showed its wild side by sharing the jungle canopy with green Amazon parrots and red howler monkeys.

“It’s kind of heartening to know that one last great wild place on the planet is full of purple martins,” she says. “It makes me feel really good about their long-term future.”

Another surprise was how fast the birds flew. The tagged purple martins traveled 250 to 300 miles per day in the first leg of fall migration and flew even faster coming back from Mexico in the spring. One returned from the Amazon region of Brazil in just over two weeks. That’s a breathtaking 360 miles per day — four times faster than the 90 miles a day estimated for other songbird species.

The pacing of the birds’ journey also challenged scientists’ notions. The tagged martins flew incredibly fast to Mexico in what Stutchbury calls a “slingshot migration” and then did something unexpected: they stopped for an extended vacation in the Yucatán, or sometimes in Central America, before continuing their journey south.

“Why go that fast for two or three days and then stop for two or three weeks?” asks Stutchbury. “We used to think these birds migrated like we drive cars. You fill up the tank, and you drive on until you get low on gas, then you stop and refill, and maybe have lunch and keep going. It makes us rethink everything we know about songbird migration.”
~~TEAMED WITH A MARTIN GODDESS~~

Member/Mentor-PMCA. I do regular nestchecks and participate in PROJECT MARTINWATCH!! Coordinated 3 geolocator studies-2009, 2010 & 2013. State and Fed licensed bander (retired Jan., 2020)
bwenger
Posts: 1046
Joined: Thu Jul 14, 2005 7:24 pm
Location: Pennsylvania/Espyville/Pymatuning Reservoir Area
Martin Colony History: Taking care of 11 active public colonies and trying to start two more in northwestern PA. Also attempting to restart another one in southwestern PA, in Collier Township's Hilltop Park. In 2017, not sure what happened but the ASY male returned and then a couple of weeks later he was gone. It could have been weather related. No other birds showed up. I had a starling nesting at the Public site that I had trouble getting rid of.
In 2018, we fledged 629 martins at all of the sites.

Thanks John for all of your thoughts over the years! They really make sense and trigger a lot more thoughts on my behalf as well as other martin landlords. Hope you and Louise stay safe from the Covid19 issues and in this upcoming hurricane season. Our year in review. Although the first half of May was bad with cold weather, and we lost some of our ASY birds, the SY birds came back and filled in their spots. The weather stayed dry and then hot but we ended up with a pretty good year. I'll take dry nests over wet nests any day. If my last 4 nests fledge, I'll be at 875 birds fledging, definitely a new record. Although we still have birds at our own colony off and on during the day and at night, I look forward to not going through over 180 smelly nests every 4-5 days. It has been very enjoyable, but sometimes becomes like a job. Maybe that is why they leave for 6 months and we get some down time and look forward to them returning in the Spring! I am glad that the PMCA and their staff, as well as people like you, Bob Allnock and Mary Dawnsong to mention a few were out there when I first started.
Bill Wenger

Building the Purple Martin population one bird at a time!
mwren
Posts: 108
Joined: Tue Mar 17, 2015 2:43 pm
Location: OH/Athens
Martin Colony History: I have had my martin colony on the dam of one of my ponds for nine years. The colony has grown each year, but I am now concentrating on helping friends and acquaintances who have shown interests in martins. My colony consists of three T-14's with 8 Troyer gourds attatched to each T-14, a Troyer gourd rack with 12 gourds, and another gourd rack with 18 Troyer gourds for a total of 96 nest cavities. I am having serious predation issues with hawks and owls and am experimenting with various hawk guards and "screens". Established successful supplemental feeding last season during late march and had a blast flipping mostly meal worms and some crickets. Faculty from Ohio University are using my colony as a research site to study parasites that target cavity nesting birds. In exchange for access to my bird trail nest boxes and martin housing, they are banding all birds involved in their study.

Bill, and John,
Great information on pre-migration activity, and review of the very interesting GPS tagging in recent years. Ever since I have been interested in purple martins, I have felt that pre-migration and migration information may be the least information available and least known time in the year. I hope that PMCA can continue to do research moving forward. John, we all owe you and Louise huge THANK YOU for all the research that you have done and made available to all Landlords !
In the past 4 seasons, I have been fortunate to be sharing my original colony with orinthologists and entimologists from Ohio University who are doing very interesting research on cavity nesting birds and the parasites that attack them. We have discussed the possibility of doing some GPS tracking of birds from this colony, but have not gotten there as yet. Could you give me any advice on who to contact on how to make this happen? The orinthologists are also certified banders, and we are averaging right around 300 chicks banded the last 4 seasons.
Again, thanks for all that you have done for our purple martins, and for all of us landlords scattered around our country!

"Bird"
Mike "Bird" Wren
bwenger
Posts: 1046
Joined: Thu Jul 14, 2005 7:24 pm
Location: Pennsylvania/Espyville/Pymatuning Reservoir Area
Martin Colony History: Taking care of 11 active public colonies and trying to start two more in northwestern PA. Also attempting to restart another one in southwestern PA, in Collier Township's Hilltop Park. In 2017, not sure what happened but the ASY male returned and then a couple of weeks later he was gone. It could have been weather related. No other birds showed up. I had a starling nesting at the Public site that I had trouble getting rid of.
In 2018, we fledged 629 martins at all of the sites.

Bird,

I am not sure if you have heard or saw it in the Update Magazine, but there is a new tracking system taking place using Motus Wildlife Tracking System, using cell phone towers. This will add an amazing amount of data to the flight statistics of purple martins. The University of Delaware has been doing some work with this in southeastern PA. The PMCA was actually hooking up a MOTUS system down in the Amazon when they were there early this year. I am looking forward to reading more information about this.

Bill
Bill Wenger

Building the Purple Martin population one bird at a time!
John Barrow
Posts: 944
Joined: Tue Nov 11, 2003 4:12 pm
Location: Corpus Christi / Sandia , Texas

Bird,

Addressing the questions in your post I would say talking to BioJoe at PMCA would be as good a place as any to investigate some type of tracking project. And I agree with Bill Wenger's comment regarding the expansion of the MOTUS tracking system, which likely is more cost effective and will see considerable expansion in the future. I know that it is being used for a number of avian species along the Gulf Coast, and as Bill indicated, PMCA has installed a receiver within the Amazon basin in Brazil to attempt to locate wintering roosts--a goal that geolocators, and the highly accurate GPS tags failed to do, largely because of the change of seasons--dry to wet--within the range.

My introduction to deploying geolocators was at the very inception of the work. We were the second location to deploy geos in 2009 and 2010. We were trained in Corpus Christi by Bridget Stutchbury and the work was focused on creating a model that would work at other locations (as well as steam line a tag and attachment method that would reliably work). We were learning what birds could be trapped to deploy, how entrances had to be modified for safety and recovery; how to recover returning birds--how to best locate them and quickly catch them to remove the tag for download. And we were trying to learn as quick as we could as we were deploying about a month before the project in PA. A failure in TX could perhaps be diverted in PA.

At that time, I believe, GPS tags had not been introduced. By my 2013 projects, (from two locations), GPS tags were available; however, the number of targeted readings were limited, making their use, in my opinion, designed to pinpoint roost locations in S. America. That was something I was not concerned with. I already had returns of approximate locations, and whether it was accurate to within 20 miles or 20 meters was not of interest to me. The GPS tags of today offer many more targeted readings, which makes their utility valuable throughout the range for various types of research. So I have never deployed a GPS tag, although Jim Ray in the TX panhandle had deployed them regularly on an annual basis.

Whether additional collaborators will be added to participate, I do not know. Although I have self funded my projects, it is my understanding that Disney Foundation is a funding source for several of the non profit collaborators. Funding is likely a looming issue on how many projects take place. The cost of geolocators that I deployed cost about $150/unit; GPS tags I believe cost about $450/unit. I renewed my permit in 2017 for a three year period. At that time Disney was hoping to deploy an ARGOS satellite tracking tag that would show live time tracking of migration--the next big step. My 2017 permit authorized me to deploy those. Although it was anticipated the tag would be available immediately; that Disney would deploy the first; and, if it worked safely other collaborators would be able to deploy those the following year. Now, three years later, and when I have decided to inactivate my permit, the weight of the tag is still too heavy to deploy on purple martins. At the time I renewed my permit the cost of each tag, including rental of satellite space, was about $6,500. Not likely to see 20 of those leaving someone's colony.

Finally, your group needs to decide and determine what they really want to accomplish. Tracking studies might interfere with the work they are already doing. Banding of nestlings might interfere with doing a tracking project. The schedule of your banders, as well as someone qualified to train them, might not coincide. Acquiring the needed tags might not be possible to accommodate a particular schedule within a very limited nesting period. In short, tracking studies are highly time consuming and invasive; both in the year of deployment and the following year of recovery.
~~TEAMED WITH A MARTIN GODDESS~~

Member/Mentor-PMCA. I do regular nestchecks and participate in PROJECT MARTINWATCH!! Coordinated 3 geolocator studies-2009, 2010 & 2013. State and Fed licensed bander (retired Jan., 2020)
Tdart
Posts: 1
Joined: Sat May 23, 2020 8:14 am
Location: Olney, MD

Last week I put up my first purple Martin house and am new "enthusiast". Should I open the doors to the house so that purple Martins migrating south take note of the possibilities for next spring? Thanks.
John Barrow
Posts: 944
Joined: Tue Nov 11, 2003 4:12 pm
Location: Corpus Christi / Sandia , Texas

Tdart, There is probably not a lot to be gained this late in the season.. For you, nest season is your first opportunity. I am not sure how much opening cavities will help you this year, but no harm in opening them as long as house sparrows are NOT trying to claim the housing, or starlings are hanging around. If you do keep it open I suggest you pull the house down in 2 or 3 weeks when all potential martins are far to the south of you. Keep it lowered, or better still bring it inside during the winter months. If you keep it up, keep it lowered and keep holes plugged with a short piece of pipe insulation tubing.

Go to the PMCA home page, log to research; then to scout arrival study. Link to Maryland, and look at different years. About 30 days after first arrivals are reported, raise you house and pull out a few plugs, always intent on keeping house sparrows and starlings out and away.

Wishing you the best!
~~TEAMED WITH A MARTIN GODDESS~~

Member/Mentor-PMCA. I do regular nestchecks and participate in PROJECT MARTINWATCH!! Coordinated 3 geolocator studies-2009, 2010 & 2013. State and Fed licensed bander (retired Jan., 2020)
Dave Duit
Posts: 1757
Joined: Tue Nov 25, 2003 2:02 pm
Location: Iowa / Nevada
Martin Colony History: In 2020, 60 pair with 285 fledged youngsters. 83 total cavities available, 58 Troyer Horizontal gourds and 4 modified deep trio metal house units, 1 fallout shelter, owl cages around all units. Martin educator and speaker. President and founder of the Iowa Purple Martin Organization. Please visit www.iamartin.org and join.

ATTENTION Tdart:
I know this is about migration and roosts, but I wanted to interject and answer the earlier post. "
Last week I put up my first purple Martin house and am new "enthusiast". Should I open the doors to the house so that purple Martins migrating south take note of the possibilities for next spring? Thanks."
the answer is yes, keep you compartments open for possible migrating hatch year martins to possibly investigate you new martin housing. The hatch year martins will become second year year martin upon their northerly migration in the sproing and will be your first pairs of a starting colony. Best of luck my friend.
Mite control, heat venting, predator protection and additional feeding during bad weather add up to success.
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