New Purple Martin Roost in Natrona, PA along Allegheny River; Video and Information. 2019

Ken Kostka
Purple Martin Preservation Alliance

For the past three seasons (2017, 2018, 2019), Purple Martins have formed a premigratory roost in the trees of the US Army Corps Lock & Dam #4 facility in Natrona, PA. This video was taken in late August 2018. The roost has grown to 5000 – 7000 martins, which gather in the evening into large swirling formations and eventually land in several large trees on the Corps grounds.  The roost forms all through the month of August with peak numbers occurring in mid-august.

The martins begin gathering about an hour before dark, streaming in from all directions, landing on wires and and swirling in large formations several hundred feet above the Allegheny River, eventually landing in the trees in spectacular fashion just before dark (watch video above). They disperse in the pre-dawn hours, flying off in all directions to distances of up to 100 miles to feed and explore the countryside, then regather again in the evenings. Towards the end of August, individual birds or very small groups eventually depart for South America.  This is the only known roost in the Pittsburgh area. The only other two known roosts are in Presque Isle, PA and in Waynesburg, PA.

There is a 20 pair Purple Martin colony on the grounds. This colony was established in 2005 with one breeding pair that was displaced from the Saxon Golf Course colony near Saxonburg, PA as part of a project intended to establish new breeding sites. There are several other articles about the Lock 4 colony and the displacement project on this website. I hope to publish more information and videos here about the roost in the future as time and energy permit.

0000003900000124I would find some dead martins under the main roosting tree every morning. Some had no visible marks but some were eaten. I wasn’t sure what had eaten them or whether whatever had eaten them was simply scavenging martins that had died and fallen or whether predators were climbing the roost tree and killing the sleeping martins. So in 2018, the Lockmaster gave me permission to place an electric fence around the main roost tree in an effort to discourage climbing predators. This did seem to deter most predators, but, as the one photo shows, an at least one raccoon got around the fence.DSCN3313


If you want to view the site with GoogleEarth, the address is:

1 River Rd., Natrona, PA 15065

There are also many articles with photos about the Lock 4 Purple Martin colony on this website.

Additional video of roost and Lock 4 facility:

video of roost (swirling formations) in August 24,2017:

video of martins bustling in the trees:

Below is GoogleEarth Photo of the Lock 4 facility, 1 River Rd., Natrona, PA on the Allegheny River in northeast Allegheny County.  The red lines converge in the lawn area containing the martin housing and the roosting trees. This is a restricted U.S. Army Corps of Engineers Facility, not open to the public. Viewing must be done from outside the fencing. The large parking lot to the east is a good vantage point. This is a large private parking lot that is usually pretty empty but I’d stay with my vehicle. The other viewing area is a small parklet just downstream of the Lock 4 facility. This parklet can only be accessed by way of a dead end alley. The entrance to this alley is 0.36 south of the Lock facility off River Rd. The parklet viewing area is better for watching the large swirling formations that form above the river, but the parking lot viewing area is better for watching the martins as they come down into the trees, also a spectacular sight. Keep in mind this premigratory roost forms only in August. Mid to late August is the best viewing time.


Additional Photos of Lock 4 Roost site:

Cat under roost tree before electric fence
Roost trees
Large metal tower that martins stage on
Electric fence with solar charger
Main roost tree second from left



Ken Kostka,
Purple Martin Preservation Alliance

These 18 pairs of Purple Martins died during a prolonged period of cool/cold weather. DON’T LET YOUR PURPLE MARTINS DIE !!!  When faced with three or more days of consistently poor weather (continuous rain or temperatures continuously below about 50 degrees Fahrenheit), Purple Martins begin starving to death because they do not have anything to eat.  Purple Martins eat only flying insects, such as flies, beetles, dragonflies, midges, butterflies, and the like.  When it rains continuously or the temperature gets below 50 degrees, these insects become inactive and the air is deprived of the martins’ only source of food. The only way to keep your martins from dying during these prolonged periods of foul, insect-less weather is to train them to eat large crickets, which can be purchased in bulk and shipped to you overnight.

Here it is in a nutshell: When martins have endured several days without food, they become desperate and will eat large crickets if you fling them into the air with a simple plastic spoon. You can also place the crickets on the porches of the martin housing, but flicking them into the air is much more effective in getting the martins to notice and eat them. So here’s what to do. Call Fluker Farms at 1-800-735-8537 or go to their website at  and order 1000 six-week old crickets. (1000 is the minimum purchase, and six-week old is the largest available). Have them shipped overnight by Federal Express or Airborne Express.  If you have a large colony or plan to feed them through a long period of cold weather, consider ordering more.  A martin will eat about 25 crickets per day.

The crickets will arrive LIVE in a cardboard box.  Put the whole box into a garbage bag and place it in the refrigerator or freezer for about 20 minutes.  This will knock out the crickets and make them easier to handle. (Trying to fling live crickets is difficult; they keep trying to escape.)

Locate your Purple Martins.  They may be hunkered down inside the housing. You may need to chase them out of the housing by lowering the house. Once they have landed on nearby perches, phone lines, etc…, place a cricket into the plastic spoon and catapult it (fling it) high and past the starving martins. You may need to fling several dozen before one or two martins starts to go after the flung crickets. But once one martin starts going after the crickets, the others will imitate and before you know it, they’ll all be feeding. Once they have been trained to eat crickets, you can substitute scrambled egg! But you must start with crickets; this is because crickets look like grasshoppers – something that martins normally eat. The wings and legs are critical because theses body parts allow the martins to recognize the crickets as a potential food item!

Check newspaper for weather forecast  Monitor you birds closely during poor weather. Look for listless behavior and drooping wings. Your birds may resort to “communal cavity roosting” which means they pack themselves into one cavity for shared body heat. Don’t wait too long to act. When martins start falling to the ground and dying, it’s usually too late!

If you are not going to feed, then don’t lower the house, and hope for the best but check the housing as soon as the weather breaks and remove any dead martins that might be blocking the exit of live ones huddled inside.

IMPORTANT: Once you have trained your martins to accept tossed crickets, you can substitute marble-sized pieces of scrambled egg, which is much cheaper and more readily available!!  Keep in mind, it’s much easier to fling the crickets/egg with a plastic spoon instead of by hand/arm. To make scrambled egg in a microwave, place eggs in a large glass (microwavable) bowl, mix, microwave for 1-2 minutes, mix again, and repeat until egg is fully cooked (but no overcooked). Once the martins have learned to accept the egg when flung into the air, you can place it on a feeding tray or platform. Doing so saves the martins from expending energy by flying around waiting to get their chance at a piece of egg.

IMPORTANT: With the increase of emergency and supplemental feeding, some martins at an untrained colony may already be trained to eat egg without you being aware of it! This is because they may have dispersed from a colony that was already trained to eat scrambled egg.  Most landlords whose colonies are trained to accept supplemental feedings use scrambled egg because it is MUCH cheaper and more readily available, so thousands of martins all across the USA are already trained to eat scrambled egg.  So try tossing (flinging with a plastic spoon) several marble/pea sized chunks of scrambled egg towards the hungry martins. If there is a martin trained to eat egg (and they are hungry), they will go after the egg and others will imitate, just like with the crickets.


More supplemental feeding articles: 

40 Starving Martins Eat 900+ Hand-Tossed Crickets at Amish Colony