MINIMIZING MALE MARTIN NEST DOMINATION THROUGH HOUSE DESIGN
From: Steven Kroenke, Tallahassee, Florida
Date: 10/2/99
Time: 1:03:58 PM
Comments
So you think martins "enjoy" nesting together in close quarters in multi-room houses. Well, think again! Martins, like all birds, have territorial drives and though martins are colonial nesters, they readily defend their nests from other martins.
When I started my boyhood martin colony at my grandparents' home, I first erected Trio aluminum and similar designed homemade wooden houses. These houses had rooms side by side and all shared a common porch. I also had a Trio 24 room aluminum hexagonal (six sided) castle.
What I noticed immediately was that male martins typically dominated entire sides of the 12 room Trio houses, as well as similarly designed wooden houses. Usually one ASY male would control one side and another would control the other. I remember the frustration of watching my 30 room wooden house with 15 rooms per side completely dominated by 2 ASY male martins! They would not allow any other male martins nor house sparrows to even land on the porches. Typically, these designed houses were about a third full on average with each 12 room house occupied by 4 pairs of martins. Sometimes I would achieve a 50% occupancy level and that was great. I rarely succeeded in achieving occupancy levels of more than 50% in such houses.
However, I noticed that more male martins would set up territory in the hexagonal houses since the rooms were spaced further apart, though there was some vertical intraspecific competition on each of the 6 sides. This involved male martin martins defending rooms below and above their chosen site. It seemed the more isolated the nest compartment was from the other compartments the greater the chances for more martins to nest in a multi-room house. I achieved 75% occupancy levels, and sometimes more, in the Trio castle and similarly designed Heath houses. The hexagonal houses attracted more martins than the houses with rooms side by side.
I often wondered why male martins were so territorial and why they dominated so many nest compartments in a house. It appeared to me they did this for 2 major reasons: (1) to reduce intraspecific competition for available females; and (2) provide females with a number of potential nest sites since the females actually select the nest site. By dominating as many rooms as he could, the male martin prevented other males from moving in and competing for females; this increased his chances of attracting a mate. Also, the more available nest sites to select from, the more attractive the territory is to the females.
The nest domination behavior is most prevalent during male territory and mate selection and during nest building. Once a martin pair has started serious nesting building and restricts their activities to one compartment, then male nest domination behavior tends to weaken. However, not always, and some males, along with their dominating mate, continue to hold as many compartments as they can. After egg laying, then the male's attention is devoted to his family responsibilities and he devotes less time to controlling other compartments.
What can you do to minimize male nest domination behavior and increase the number of pairs in a multi-compartment house. First, you can try porch dividers to separate each compartment and give some territorial privacy. I tried this approach, beginning in 1970, and had some success. The male martins could still navigate around the dividers and control several rooms. However, I did notice that I had more 50% occupancy levels than in the past, so dividers do help. Porch dividers greatest benefit is in preventing the potentially disastrous "baby martin wandering syndrome". Baby martins will come out and crawl along the porches. I had big problems with baby martins crawling along the porches on my hexagonal houses, where martins nest side by side, and entering other nests. Large young moved into nests with small babies and naturally got most of the food. Fights broke out as the parent martins of the small young tried to force out the large young. Any young on the porches are viciously attacked by other martins, particularly SY males. So the porch dividers should be a part of any house design that uses a common porch.
Probably the best approach is to use a house design that is vertically stacked so that each compartment has its own SEPARATE porch and thereby provides the territorial privacy that martins like. Plus such a design completely eliminates the "baby martin wandering syndrome". The T-14 is an excellent designed house that incorporates this concept. You may see some vertical intraspecific competition between males initially, but such a design is much better than houses with rooms side by side and sharing a common porch. The hexagonal houses are good, too, provided you use porch dividers to prevent baby martins from crawling between rooms.
Of course, the other alternative, which completely eliminates the "wandering baby martin syndrome" and nearly all male martin nest domination behavior is my favorite, gourds. A gourd cluster with gourds facing different directions can achieve 100% occupancy levels. Initially, male martins may control several gourds during the early part of the season, particularly if they are side by side and facing the same direction. However, gourds provide the territorial privacy that martins like and keep male martins for the most part out of each others' feathers. Gourds are excellent nest sites and often succeed where houses fail.
Steve Kroenke
