Questions and Answers About Feeding Purple Martins
(by Edwin W. Donath)

Since publishing my article: "How to Feed Mealworms to Martins" published in the Purple Martin Update, Vol. 4(3):2-4, 1993, I have been asked many additional questions about this topic. So, below, I answer the questions asked most frequently.

Q: If I provide the martins with a feeder platform supplied with suitable food every day, will they become dependent on me and lose some of their ability to survive on their own?

A: No. When their natural food is available they will ignore your supplemental food offerings. Their use of the feeder increases in proportion to their stress level. Their average stress level is highest during the last two weeks before fledging the young, and the first week after that. Typically, fledged young returning to the nest box for the night are fed heavily from the feeder, in both good or bad weather. By contrast, early in spring when the birds are busy pairing up and defending territory, the weather has to be very bad before they will come down to the feeder. This may be discouraging to landlords trying to coax martins down for the first time, early in the season.

Q: Does this also apply to food put on the porches or in the nest boxes?

A: No. Once the martins accept mealworms as food, they will take them rain or shine from porches and nest boxes. It is remotely possible that continuous heavy feeding in this manner could affect their behavior adversely. To be on the safe side, feed only token amounts at the houses until severe weather occurs. Late in June 1993, we used the Orange Star Martin Feeder (pictured here) for the first time and it was so successful in providing equal access to the food for all our martins that we severely curtailed our in-house feeding during the 1994 season (see Update 4(3):2-4).

Q: Mealworms are deficient in calcium and phosphorus and, therefore, are not suited for long-term exclusive feeding. What can I do to provide the martins with a more varied diet?

A: Place the mealworms in a container with a one-inch-deep bed of slightly-moistened chicken starter mash. After a day of feeding, the mash in their gut will provide the missing minerals. The insects in the martins’ normal diet have the same deficiency, which leads one to wonder if the insects’ lunch contributes minerals to the martin diet or do the martins get the bulk of their minerals from soil and shell at the waters’ edge when they feed on grit?

In our urban area, a few bits of shell and stone begin to show up in the nests when the young are about a week old. In some nests, many bits of glass are also found. It seems reasonable to conclude that some martins are confusing reflected light from the glass with that from wet shell, and when fed to their nestlings, the glass is rejected.

We have supplied our martins with ground oyster shell, cuttle bone chips, and mineral block chips for many years, with few takers. However it’s done, the martins seem to prefer their own method of acquiring minerals.

Q: How many mealworms do I need to feed my martins whenever they are willing to come to a platform feeder?

A: It depends on the weather. In 1993, our martins consumed about 10,000 large mealworms per pair. In 1994, a year with more favorable weather, less than half that many were used per pair. In 1994, they took more people food (i.e., scrambled egg, shredded cheddar cheese, and some large-curd cottage cheese) when feeding the young. Before the young hatched, they ate very little of this, preferring the mealworms. After your birds are taking mealworms readily, add egg and cheese by placing it on top of the mealworms. The martins will learn to take it, but they prefer the mealworms.

Q: Can I raise my own mealworms to save the expense of buying them (i.e., 10,000 mealworms cost about $37 delivered)?

A: Yes, but I don’t recommend it for everyone. It’s a time-consuming chore that is better left to professionals. Just for the experience, I am raising a batch of them for use in 1995. Briefly, my method is to place a few hundred worms in an 8-quart plastic box, with a 2-inch deep mixture of wheat bran and chicken starter mash. Air holes are drilled in the box top along the outer edge, permitting the boxes to be stacked without covering the holes. At the start, and once a week thereafter, I spray a mist of water on top of the mash. I have ten boxes, so that if one goes bad, the whole lot won’t be destroyed. The worms turn into beetles that lay eggs that hatch into many more worms. The cycle repeats every 3 or 4 months. Things proceed more rapidly at 80 degrees Fahrenheit, and slower at cooler temperatures. The trick is to end up with worms during the martins’ nesting season. Perhaps one of our members can give us more helpful information on raising mealworms in large quantities. [Editorial comment: Most directions for raising mealworms suggest placing a couple apples, cut in half, down in the mash (with the cut surface up, but flush with the mash surface). The worms will eat this for their moisture needs.]

Q: What is an Orange Star Martin Feeder?

A: By the last week in June, 1993, the martin congestion at our mealworm feeder had reached chaotic levels, as 7 pairs were taking food to their young during bad weather. A radical design change was necessary. So a larger platform feeder, in the shape of a star, was introduced. Order was restored. A martin could now land on one of the unoccupied star points, wait a moment for a clear path to the food in the central area, snatch a bite of food, and quickly return for takeoff. My star feeder design will accommodate a dozen pairs of Purple Martins at a time, without overcrowding.

My platform was cut from a 4-foot-square piece of 1/2-inch-thick, exterior-grade plywood and painted bright orange for maximum visibility. It was supported 6 feet above the lawn on metal legs. An 18-inch-diameter, 3/32-inch-thick, clear Lexan® roof was supported by a single post, 6 inches above the central area. This material is sold for glazing by building supply houses. It is practically indestructible, but rubbery enough to soften the blow if a bird collides with it.

Q: Once I build the feeder and acquire an adequate supply of mealworms, how do I get the martins to take them from the feeder?

A: First they have to learn to accept mealworms as food. We discussed this in a prior Purple Martin Update (Vol. 4(3), page 2). Briefly, the method is to fasten a small tray of worms firmly to each house, out of the rain. Supply each tray with token amounts of mealworms until bad weather is forecast, and then increase the supply to 50-100 mealworms per resident bird. It helps to add any active insects to the tray. After the martins are seen eating the worms, transfer the trays to the starfeeder on the next bad weather day.

Here are some other suggestions that may help, though I have not tried them: Toss some worms in the air near the feeder (see Update Vol. 4(3), page 18). Play the dawnsong tape on top of the feeder (see Update Vol. 4(3), page 20.) Put some decoys next to the trays (see Update Vol. 4(4), page 2). Put some egg shells, and a tray of mealworms, on the feeder.

Q: This all sounds great for the martins, but I don’t have the time to devote to what sounds like a long, involved project. However, I would be willing to help them during a rare martin-killing storm. What would you suggest?

A: Okay, here’s my best advice. A month or more before your martins are due to arrive, order 1000 giant mealworms and have them delivered near the due date. Put them in an 8 gallon (or larger) covered plastic tub with 2 lbs. of wheat bran or some other grain-based food. Punch a couple of dozen air holes in the cover. Spray a light mist of water on top of the grain once a week [Editorial comment: See apple recommendations, above]. Store the tub in a cool place above 40 degrees Fahrenheit. Wait for bad weather.

If cold weather, or continuous rain, persists for over 24 hours, with no relief in sight, place a small container with 20 worms per occupant into each nest cavity. A small baby food jar would be good. Twenty worms (17.4 grams) are just enough to keep an inactive 50 gram martin alive for 24 hours. If you only have large (as opposed to giant) mealworms available, supply 45 per bird per day. By the way, any leftover giant mealworms make great bait for panfish, if you’re a fisherman.

Q: What is a giant mealworm?

A: Giant mealworms are ordinary mealworms that have been treated with juvenile worm hormones, thereby greatly prolonging their worm stage. As a result, they grow to a size 2&1/2 times larger than normal. During June and July of 1994, we kept a supply of them in a cool, but unrefrigerated, area and only a few of them became beetles. Their 1000 lot price per pound is close to that of large mealworms. In larger quantities they are not as steeply discounted as large mealworms are.

We started to put giant mealworms on the feeder when our first nestlings were one week old. The purpose was to reduce the number of trips the parents had to make to the feeder, since in 1993, with rare exception, they took mealworms, one at a time, up to the nestlings. During the 1994 season, a few of the hens began taking 2, 3, and 4 large mealworms at a time. This was a giant leap forward for birdkind.

Q: I can’t afford to buy mealworms. What are my chances of getting the martins to eat scrambled eggs?

A: Your chances are slim in bad weather, none in good weather, and at this time, unknown during martin-killing weather. Place the egg in the nest box entrance holes so the martins can’t help but run into it. It’s worth a try in bad weather.

Q: Do other birds come to the feeder?

A: Yes. Our resident chickadees and cardinals come to get mealworms to feed to their young. In early spring, some migrating thrushes also have learned to come to the feeder for breakfast. Actually, we are in a very poor area for birds. In better habitat, warblers and many other insect-eating birds would certainly be attracted to such a feeder. House Sparrows with young are a problem. We have to destroy thirty of them a week during the martin season. All the local songbirds learned to come to the feeder when I rang the dinner bell prior to filling the feeder, so I had to stop that. Our robins are trained to come to their own mealworm dish, now. They take a dozen or more at a time.

Edwin Donath has been a martin landlord for over 32 years. He is a retired, 70-year-old designer of industrial instruments.

Reprinted with permission from the PMCA Update magazine, Vol. 6(1), pages 6-8

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