Final Purple Martin Report For 2007

[Steve Kroenke]

Final Purple Martin Report For 2007

What a fantastic purple martin season for our two personal martin colonies and eight satellite sites in northwest Louisiana! Hundreds of martins nested and hundreds of fledglings were raised. We had 380 + martin pairs in our two personal colonies which fledged well over 1500 youngsters. We had 200 + pairs in our eight satellite colonies which probably fledged over 600 babies. Therefore all of our martin colonies had close to 600 pairs of martins which probably fledged over 2000 youngsters. The 2007 martin season has been the best one I have ever experienced relative to number of pairs and young since I started studying martins 40 + years ago.

Housing Types In My Personal Martin Colony

There were 286 cavities with round holes in my colony this season. Cavities were easily monitored via rope/pulley or winch systems and nests could be checked via gourd access ports and house compartments with doors that are easily opened or removed. My housing consisted of the following types: 107 natural gourds; 33 Super Gourds; 70 Troyer horizontal gourds; two 12-room Trendsetter houses; one modified Trio Castle with 12 rooms; two modified Trio M-12s with six compartments each; and two Lone Star Goliads with porch dividers, one with 12 rooms and one with 16.

Number Of Martin Pairs By House Type

For my third season in northwest Louisiana, I attracted 254 pairs of martins and that represented an occupancy level of 89%. There were 160 ASY pairs and 94 SYs. Not all pairs were successful in fledging young. My first season, 2005, I attracted 81 pairs of martins, 28 ASYs and 53 SYs, and my second, 2006, 175 pairs, 118 ASYs and 57 SYs.

The martins colonized the various cavities as follows: 100 pairs in the natural gourds for an occupancy level of 93%; 29 in the Super Gourds for an occupancy level of 88%; 60 in the Troyer horizontals for an occupancy level of 86%; 19 in the Trendsetters for an occupancy level of 79%; 24 in the Goliads for an occupancy level of 86%; 10 in the Trio M-12s for an occupancy level of 83%; and 12 in the Trio Castle for an occupancy level of 100%.

There were 189 martin pairs in the 210 gourds for an occupancy level of 90%. There were 65 pairs in the 76 house compartments for an occupancy level of 86%. So, there was not a big difference in occupancy levels between gourds and houses in 2007. However, natural gourds still had an overall better occupancy rate than other cavity types.

Number of Eggs/Nestlings

Due to the large number of martins nesting in my colony this season, I did not keep detailed records of the number of eggs/nestlings, but focused on monitoring for problems and determining the number of pairs. Based on several major nest checks and targeted ones for specific pairs, I believe I had between 1100 and 1200 nestlings in my colony this season though not all successfully fledged. As expected in a large colony, there were eggs that did not hatch and some dead nestlings were found in the nests. Also a few small nestlings were removed by bachelor SY males. Additionally there were some youngsters that fledged prematurely or in the absence of their parents and these babies perished without parental guidance. But overall, the hatching and nestling survival rate was quite good.

Oyster Shells For Grit and Calcium

I substituted oyster shells for regular egg shells and this worked fine. Though I still believe martins may “like” regular egg shells better, both male and female martins fed huge amounts of the oyster shells to their young. The parent martins ate the shells, too. In fact, the martins spent a large amount time it seemed going to the oyster shells which I placed on an elevated bed and breakfast platform and the ground under my housing. The martins preferred going to the ground to obtain the oyster shells.

The female martins “tried” to eat the oyster shells during the time when the females were ready for breeding, but the males violently attacked and sexually assaulted them. Male martins KNOW when a female martin is ready for fertilization and if she is on the ground looking for a source of calcium that is a clear sign of her sexual state and the males will pounce on her. Time and time again I watched female martins try to sneak down to the oyster shells, but gangs of males immediately went after them. The females had an easier time getting the oyster shells from the bed and breakfast as their mates could offer better protection from other males at that height.

Bachelor SY Male Infanticide Behavior

Every year in my martin colony, bachelor SY males commit infanticide on established ASY and SY pairs with small nestlings. The single males are desperate to obtain territory and a mate and the only way to possibly “steal” a cavity with martin residents is to eliminate the babies. Once the young are removed, this action may then cause the established male to abandon the territory and the female would then be available for mating with the SY male. Such infanticide behavior occurs in other animals, including African lions where new males take over a pride and kill all the cubs fathered by the displaced original males.

I was able to mitigate somewhat the adverse impact of many single SY males as potential baby martin killers by erecting housing specifically for these martins in April. April is the big month for SYs to return to northwest Louisiana. I erected two 12-room Trendsetters and a 12-room modified Trio castle during the first of April. These houses attracted 28 SY pairs and three ASY pairs. So this system did help minimize infanticide behavior by giving many of the SY males unoccupied territory to claim rather than try to usurp an active martin nest. I plan to continue this approach in subsequent years with either new housing or I will keep some cavities closed until the SY males arrive.

Starlings And House Sparrows

Starlings and house sparrows were not a big issue with our personal colonies this season and were not in 2005 and 2006. I shot five starlings and trapped one from January until mid-May. None of the starlings established territory or caused any harm to the martins and most were shot when they landed in a tree or flew over. I shot only one male house sparrow in February as he perched in a pear tree. However, everything can change one way or the other and next season we may have more of these pests to eliminate. Of course, if I did not shoot/trap these starlings then they may have taken over a house compartment or gourd though our huge numbers of martins even intimidate starlings.

At Bob’s colony, I observed a martin defensive behavior that I have never seen before relative to inter-specific competition: martins “ganging up” on a single male starling in mid-May and chasing him way out in to a nearby cow pasture and driving him to the ground. I have never seen anything like that before and this “coordinated” defensive behavior by martins against starlings could gradually be evolving into a “standard” modus operandi in response to starling competition. Of course, we may only see this in huge martin colonies where a starling may “violate” the territories of multiple martin pairs and they all respond in defense of their cavities. This behavior is probably not true communal defense, but an aggregate of martins attacking based on “collective” independent aggression. I thoroughly enjoyed watching a mob of martins chasing the starling at high speed through the yard! The martins were mobbing and physically attacking this lone starling which never put up any defense. Once he plunged into a pear tree in Bob’s backyard to escape the martin mob and a male martin went into the foliage after the starling! In fact, he was driven from one house to another by mobs of martins. I saw him in the morning on his arrival and finally shot him in flight at around 8:00 pm that same day when he was trying to roost in one of Bob’s Trio castles. That was the last starling of the year.

So far, shooting/trapping is the option of choice for permanently ridding our personal colonies of any potential starling problem and there is no need to use srehs in lieu of round holes which the martins prefer. We do use only crescent entrances in our satellite martin colonies because of greater starling problems in urban locations and we can’t monitor the sites on a continuous basis.

Rat Snake Predation

Amazingly, I did not catch a single rat snake in my net traps. But rat snakes, particularly black and Texas rat snakes, are in this area and I have found some dead ones on the road near my colony. Bob did have some rat snake predation and caught a huge black rat snake in one of his net traps.

Accipiter Hawk And Merlin Predation

The number one cause of mortality for adult and fledgling martins in our colonies was due to predation by migratory and resident Accipiter hawks and probably migratory merlins. This mortality was also experienced in 2005 and 2006. I observed numerous “visits” and attacks by migratory sharp-shinned and Cooper’s hawks and by migratory merlins from February until early May. I witnessed five kills: one ASY male by a female sharp-shinned hawk; one ASY female by a male Cooper’s hawk; one ASY female by a female Cooper’s hawk; one ASY female by a female Cooper’s hawk; one “unknown” ASY by a female sharp-shinned hawk. In all these successful attacks, the martins were ambushed and caught off guard and I was unable to intervene quickly enough. However, in two cases, I forced the hawks to drop the martins which later died. No doubt, many other martins were caught by Accipiters away from our colonies. Martins can out fly Accipiters once the martins are fully accelerated. Accipiters usually catch martins by surprise at low altitudes when the martins are at a disadvantage and unable to quickly gain speed and altitude.

I observed numerous attacks by migratory merlins, which are small high-speed falcons, but none was successful. Some of these attacks were spectacular with the merlins chasing multiple martins in fast breath taking pursuits. The merlins were a match for the martins in level flight and a dive and the martins could not escape by speed alone. The martins were faster in a climb. The martins were able to evade the merlins with quick banking actions. The merlins were unable to follow the martins’ agile aerial gymnastics for any extended time. Martins are better able to avoid the fast merlins than the more maneuverable Accipiters which often can match a martin’s banking actions. Merlins are much faster than Accipiters though not as agile in quick turns or slow maneuvering banking.

My active presence around our colonies and constant guarding of the martins stopped untold numbers of attacks by raptors and prevented large numbers of martins from being killed. Many times Accipiters and merlins would fly over and circle, looking for vulnerable martins that would leave their cavities later. I would confront these raptors and they never attacked when they knew I was there. I also maintained vigilance during the early mornings and in the evenings at roosting time and this kept the Accipiters and merlins at bay for the most part.

The greatest mortality occurred when the martins began fledging their young during the last of May and through August 1. Huge numbers of fledglings were in the area and the resident Cooper’s hawks caught many. From May 31 through August 1, I observed 59 successful attacks by Cooper’s hawks on recent martin fledglings. These fledglings were still just babies and were no match for the hawks and none escaped. I am estimating that the hawks probably caught between 100 and 200 martin fledglings this season, as no doubt many attacks occurred out of my observational range.

The Best Purple Martin Season So Far

The 2007 purple martin season in northwest Louisiana was spectacular. Our area probably has one of the highest concentrations of purple martins in the country. We have two super martin colonies side by side with 380 + pairs and about six miles northwest of us is another outstanding super colony. This is the colony of Al and Ursula Scott which had its second season in 2007. I believe they attracted over 150 pairs this year. Plus there are many small colonies all over the place and we have eight satellite sites and plan to expand them in 2008. All the 2007 fledglings which survive to become SYs in 2008 will hopefully seed new colonies and increase the size of existing ones. We could probably attract over 500 pairs of martins to our personal colonies in 2008 if we erected more housing. We are living in purple martin paradise!

Steve

[Steven Spencer]

Thanks for the report, Steve. It must have taken hours upon hours of observation to come up with the data you collect. But your retired, right! The only way we can learn though is through record keeping and testing new ideas and methods. Your place is a martin laboratory! Again, we appreciate all you do teach us about this wonderful bird.

I like the idea of putting up housing later in the spring specifically for sy's. It gives these young birds the opportunity for their own space to breed and keeps them from snooping around established nests.

I remember you and Bob mentioning the porch domination issues at some of the housing this year. Have you noticed in your colony if porch domination is mostly a trait of asy's compared to the sy's? For instance, on the housing you opened later in the spring, did the sy's show the same porch domination at this house compared to other housing that was predominantly asy's? At my colony the asy's claimed the early compartments and defended several when the sy's showed up later in the spring. That seems to be the time when the major fighting ensued.

Thanks again.

Steven

[Tim Mangan-Kansas]

Steve:

Nice year end report. Do you and Bob still have martins in the area? I hope you and Bob are able to put something together for next year.

Yesterday was the first day I did not see any martins in the area. I have learned one big advantage with a second year colony is the additional time you get to have the martins around. They arrived almost three weeks earlier this year and I had martins in the area everyday for an additional three weeks over last year.

They are now gone so back up goes my crappie avatar.

Tim

[Steve Kroenke]

Hey Steven,

First, Bob and I enjoyed having you and your wife visit our colonies. We always like to talk martins with fellow martineers! Next year when the martins are here, we are looking forward to seeing you again.

I am glad you liked the report and thanks for the comment. I do spend a lot of time studying martin biology and behavior at a detailed level and learn many things. Having a huge martin colony provides one with the opportunity to see things that a smaller site may not experience. Yes, it is like an outdoor laboratory! It does take many hours of observation, but I am retired and can't say I don't have the time!

I have seen nest domination behavior with both ASY and SY male and female martins though ASYs tend to exhibit this irritating trait with greater intensity. The SYs are usually not nearly as aggressive relative to dominating multiple cavities as ASYs. SY males tend to be equal in aggressiveness with each other while these males are often subordinate to the ASYs. For example, in my modified Trio castle with 12 rooms, all cavities were taken by SY pairs within about a week with some initial fighting. The same thing happened with my two Trendsetters though there were three ASY pairs, two of which dominated an additional compartment each for the entire season.

Next year, I will probably replace some of my smaller gourd racks with larger ones to help out the SYs. I may close half the gourds on these and not open them till April. I will also add a T-14 for the SYs in April.

Steve

Hey Tim,

We don't have martins now. But we had martins continuing to roost in our colonies until around August 8! I was amazed that sometimes as many as 20 martins, mainly fledglings, were still roosting during that first week in August. This is the longest I have ever had martins at any of my colonies. Some of my late nesters brought their young back to roost for almost two weeks.

We hope to have some kind of martin get together at our colonies next year, but it is still tentative. I have had folks from parts of Texas express an interest and several have visited my colony this year.

Since the martins are gone, I am now transitioning into the deer hunting mode. We have been working on our hunting lease. This will be my second hunting season and I am still learning!

Steve

[blanchar40]

Your observations on egg shells versus crushed oyster shells. This year I tested both by placing 2 pans elevated and putting oyster shells in one and egg shells in the other. Also, placed a sampling of each on the ground in different locations. Females proffered the elevated egg shells by a very wide margin both for themselves and their young. The males were about 50-50 on their choice for elevation and shells. It should be noted that each elevated pan also had regular aquarium sand & I wasn't always able to see what they were selecting.

[Steve Kroenke]

I wonder if the females prefer the elevated locations in an attempt to minimize the sexual attacks by males, particularly earlier in the season prior to egg laying. When the females were gathering oyster shells for their young, the males with nest bound babies rarely attempted to copulate with them. At this stage, the females do NOT have any internal eggs to be fertilized and the males KNOW it.

Next season, I will continue to offer crushed oyster shells (pullet size) in both my bed and breakfast platform and on the ground. I did notice martins liked to land in a cleared area with exposed earth or on my gravel driveway for the oyster shells.

Steve

[Donnie Hurdt MN]

I enjoyed reading your year end report Steve. I wish your coloney was closer to mine thenm I would have a chance at your overflow! Maby when I retire I should move down by you ! Martins are gone from over head here too, I suppose they are all at the Avon roost near here. I went opt the Avon roost about a week ago but only saw about a hundred martins and the water pump went out on the boat moter and I had to be towed to the boat landing. Not a good expirence. Better luck for me next year I hope.

[Steve Kroenke]

Hey Donnie,

I am glad you enjoyed the report.

There is plenty of land down here in Louisiana and plenty of martins! The martins need good landlords such as yourself and I know you would take good care of them.

Northern martins will probably be still coming through our area for several more weeks though I haven't seen any martins lately.

When I lived in the Tallahassee, Florida area, I remember seeing martins as late as October and even November once down on the coast around Apalachicola. These must have been real late northern martins that were preparing to make their trans gulf flight to the Yucatan.

Hopefully next year you will be able to attract martins to your site.

Steve