Corpus Christi roost regenerates with northern PMs

[John Barrow]

On July 7 we located the roost of local birds totaling about 10-15,000 martins. History/location of the roost can be found on the PMCA roost page. Followup visits to the roost established a peak of 20,000 martins on July 26, and dispersal had occurred down to 10-15,000 on July 30. What we thought would be the final observation was made on August 8 and numbers had dispersed to 2,500 martins. I expected the roost to completely disperse within a week, although there was the possibility the remaining birds would intercept and attract passing martins from the north because the roost had held intact almost 3 weeks beyond normal dispersement dates. Passing northern roosts typically arrive in late August.

In addition, we enjoyed some late second nestings at established colonies. My last nestlings, the second successful brood of the season in that gourd, fledged on 8/3 and continued to stay in the gourd at nights until at least 8/14. Another landlord had last birds fledge on 8/5. We expected the Summit Apts roost to disperse shortly after these late fledglings were strong enough to migrate south.

Acting upon information from a resident tenant who we have encouraged to monitor the roost, a followup visit was made last night. The roost now harbors 35-40,000 martins, which most probably represents the interception and attraction by remaining local roost residents of a passing northern roost that has dispersed. This phenomenon has not occurred in the past 6 years that we have monitored roost activity in the area. In addition, a large staging area that forms about 5 pm in the afternoon has been located at an area that northern migrants have used in the past. The staging area consists of about 6,000 martins that are perching and preening on utility lines on the south side of the shopping center where Two Georges restaurant is located on Everhart south of Holly Rd. We hope to scope martins at the staging area beginning today to try to determine the origin of the new martins. In addition we would appreciate knowing of any large dispersals from other roosts that might be feeding this most southern area. It is possible this roost will now remain intact until late Sept to mid Oct. It is easily viewed and like all roosts, quite impressive to see.

We are fortunate to have this occuring within two miles of our home, and to be going into our seventh month with local birds still present, my earliest arrival coming on Feb 6 this year.

[Laverne]

Hello John.

It has been 16 days since I last visited the Sharpstown Roost. I'll have to get over there to see if the numbers are declining.

It would be nice to hear reports from the Dallas/Fort Worth area and Austin, as well.

I've often wondered if Purple Martins "roost hop" as they move south through the breeding range. I'll bet they do. Do you have any information regarding this?

[John Barrow]

Hi Laverne. I don't think there is any question that martins "roost hop" on their southern journey. It is much like their northern journey, except we are dealing with much larger groups and numbers. You will recall last spring when martins began arriving along coastal Texas. Those of us with some established colonization would often have our local birds return to housing in the evening with 25, 50 or even several hundred martins in tow. Those would spend the night and likely be gone the next morning weather permitting. The best attractor of migrating martins is martins already present.

In the roost scenario you have thousands of martins spreading out in different directions to forage during the day. I have no doubt that these birds intercept martins from the north that have dispersed from their original or most recent roost to travel south. How far they would travel before stopping to roost and refuel is something I don't know, and it may not be constant. I think most of us underestimate the flying ability of martins and their capacity to travel great distances. In favorable weather a large percentage of martins from any roost in Texas and perhaps much farther north could likely overfly Corpus Christi and fly directly to the Yucatan if they had to. But when they intercept resident birds that are already roosting there is probably some urge to check out and join with that group. At least that is the result we have seen down here. Or bad weather/feeding conditions could make the decision for them.

We generally have two roosts that have some annual establishment in CC. First we will have a roost that forms in late June and builds through July up to several thousand martins. I believe it is composed of primarily local birds (within several hundred miles). In the past that roost has completely dispersed by late July/early August and we will see few if any martins until late August when numerous martins from the north begin to show up. In 2001 (Aug. 30) we located a roost on its first day of formation consisting of approx. 75,000 martins that arrived that day. It had to be the dispersement of a large roost located elsewhere. Within a week over half of that roost had dispersed, but the roost remained active, growing or dimenishing in numbers of thousands of birds per week, until early Oct when the roost steadily declined to complete dispersal near mid Oct. Other roosts have followed that pattern, but no latter stage roost has reached the numbers of 2001 and one reported in 1999. Also these latter timed roosts have always established at a different location than the local roosts, although not far away.

What is unusual this year is that the breeding season has lasted a long time, the local roost has not completely dispersed, and it now appears that the 2,500 or so remaining birds from the local roost has intercepted a large group of migrating martins and attracted them to the local roost site. This roost could grow to a very large number and fluctuate in size until mid fall, or it might all be gone next week. Time will tell. During that time we hope to find some clue of where the new birds originated from. It might be like looking for a needle in a haystack, but we are going to look.

I hope this answered your questions. Best wishes, john

[Louise Chambers]

this is just a test! trying to add link to photo album from staging area we viewed on Aug 15 in CC

http://www.kodakgallery.com/BrowsePhoto ... rt_order=0

if this won't work, I'll just post a few photos

What amazes me is that the staging area held just a portion of the martins that assembled at the roost - and that all the birds eventually roosted in TWO trees - it was awesome to watch them vortex and fly into the trees. The smell from below the trees was also awesome. This same apartment complex also has roosting Great-tailed Grackles, so the noise of the grackles at times drowns out the martins - plus the grackles are molting and the ground is littered with feathers. Grackles and martins do not roost in the same trees.

Louise

(Everyone, thanks for sharing your roost observations and wonderful photos. PLEASE be sure to report your findings, or lack of, on the Project MartinRoost page!!!! It is very important that you do this, so please take the time to file your report there, as well as sharing your info here on the Forum.)

[Guest]

Just wanted to let you know that the premigratory roost in Lewisville, TX has departed. This year the martins were about 50,000 . Sometimes a group will depart while the others still linger on to wait for some martins coming from the north. Not this time. Bill Thomas reported seeing the martins getting restless one week ahead of departure. They do not sit on power lines anymore. They come in from high above and then go straight down to the trees to roost. Bill visited the roost on Saturday, 13th of August 2005 and they were coming in as always. Sunday the 14th of August he waited and no martins appeared. So he knew that the martins were off on their migration. The moon phase was about 90% of a full moon and that will give the birds about one week of good flying sight at night. This departure is early this year compared to Sunday, 7th of September 2004. and 2003 if was late August. I have a feeling that the lack of iinsects has a lot to do with this. Visited the Houston Sharpstown Mall roost on Sunday evening, 14 th of August 2005 and there still had over 200 thousand of martins there. Gisela (PMLNT)

[Laverne]

The Sharpstown Roost in Houston has not dispersed, yet. We were there this morning and the population is still high.

We watched the birds leave the roost this morning and they all headed SW - so they may be on their way to Corpus Christi as we speak.

I'll try to get over there and check on the status of this roost again in about a week. They've gotta be close to vacating this site. Then, again, maybe the Sharpstown Roost has been replenished by birds from the Lewisville Roost, and the Tulsa Roost, and the OKC Roost...

Thanks for your report Gisela. And thank you, John and Louise, for your informative posts. This roosting business if fascinating...