Martin-Killing Weather of April 2007
Purple Martin Preservation Alliance
T.S. Elliot said "April is the cruelest month," and he would get no argument from the 20 Purple Martins that were forced to endure an agonizingly-long two week period of cool, wet, martin-killing weather that lasted from April 5 through April 19th, 2007 in southwestern Pennsylvania. With the help of their dedicated martin landlords, all survived except for one - an adult male (ASY-M) that died on April 9 at Moraine State Park. He weighed 39 grams. (A healthy martin weighs 50 grams). He had the bad luck of being alone (more about that later), and of arriving after the bad weather set in, causing him not to be noticed for several days.
Working with martins is always a learning experience, and this was no exception. The weather event began on April 5th, 2007, when the temperature dropped from the preceding day's high of 68 F to a bone-chilling high of only 31 F!! A number of martins had already returned to several sites in southwestern Pennsylvania. There were three martins (all ASY-M) at the Saxon Golf Course colony in Sarver, PA, eight (6 ASY-M and 2 ASY-F) at the Duke Snyder colony in Butler, four (all ASY-M) at the Gastown Racetrack colony in Shelocta, PA, one ASY-M at the Zeglin Dairy Farm in Mammoth, PA, three martins at the Youghiogheny Country Club colony in Buena Vista, PA, and three martins at the Butlers Golf Course colony in Elizabeth, PA. These last three disappeared after the first day of cold weather, according to Jeff Hunt, the manager of that site.
All of the Purple Martins were sustained on a diet of scrambled egg, mealworms, and crickets. All were fed all a daily basis, sometimes twice per day. The method of feeding varied from tossing (or spoon-flinging) the food to placing it on feeding trays to placing it inside the nesting cavities. Below is a chart detailing the high and low temperatures for each day. One good thing about temperatures in the high thirties and low forties is that the food doesn't freeze and it doesn't go bad very quickly. It's as if the outdoors is one big refrigerator. At one particular site where no martins were present, but about a dozen Tree Swallow had returned, I put scrambled egg inside the Tree Swallow gourds. Some had begun communal cavity roosting. When I came back two days later, the egg was still good. I never saw any Tree Swallow eat it. I had never bothered to train them to take supplemental feedings, but I never found any dead ones, and I think it is possible that they ate it out of desperation. I also placed a small handful of scrambled egg into each compartment where one or more martins was staying, and it was always almost gone or half-eaten the next day. Incidentally, the martins always always chose to roost in the compartments on the side of the house opposite the direction of the prevailing winds.
|Date||Actual High||Normal High||Actual Low||Normal Low||Departure from Normal|
|April 03, 2007||78||56||45||35||+16|
|April 04, 2007||68||57||36||36||+6|
|April 05, 2007||31||57||25||36||-18|
|April 06, 2007||36||57||24||36||-17|
|April 07, 2007||30||58||23||36||-20|
|April 08, 2007||33||58||23||37||-19|
|April 09, 2007||38||58||30||37||-14|
|April 10, 2007||47||59||25||37||-12|
|April 11, 2007||54||59||32||38||-5|
|April 12, 2007||51||59||40||38||-3|
|April 13, 2007||48||60||35||38||-7|
|April 14, 2007||44||60||30||39||-12|
|April 15, 2007||40||61||36||39||-12|
|April 16, 2007||44||61||34||39||-11|
|April 17, 2007||49||61||37||39||-7|
|April 18, 2007||46||62||36||40||-10|
|April 19, 2007||59||62||44||40||+1|
|April 20, 2007||69||62||41||40||+4|
|April 21, 2007||73||63||39||41||+10|
It is commonly believed that when the weather gets cold for an extended period of time, martins don't die of exposure but rather of starvation. While this is generally true, I suspect that exposure may have been a big factor in the death of the lone martin at Moraine State Park. This martin ate crickets once a day for two days in a row (April 7 & 8) but was found dead the next day. But he had endured two days without any food before being discovered, and may have been too far gone to recover. Multiple feedings each day may have saved him. However, the fact that there were no other martins present may have also contributed largely to his demise - he had no other martins to huddle with and share body heat. Doing so may have allowed him to conserve enough energy to survive. Even one other martin-partner may have been enough. Keep in mind that the lows for the period April 5 through April 8 averaged 24 degrees F, eight degrees below freezing for four consecutive nights. Even a martin that had managed to eat one good meal per day and was roosting in a well-insulated wooden house might have had a hard time maintaining his body temperature alone under these extreme conditions. At the Saxon Golf Course colony, the two ASY-M's that were originally sleeping in separate compartments began roosting in the same compartment when the weather became severe. Both survived.
April 16 was also especially severe. There was snow, sleet, and strong winds throughout the day. It is amazing how Purple Martins can maintain controlled flight and hover in the face of very strong winds. There were times that the snow was so heavy that they had difficulty distinguishing snow flakes from egg chunks. One entry from my journal, dated 06 April, 2007, reads "Both fed in heavy wind and snow," referring to the two ASY-M's at the Saxonburg Golf Course colony. And the wind was at times so strong, it was blowing everything away that I was not physically holding down or kneeling on. Despite the strong, cold, sleet-laden winds, the martins managed to hold their own. They would even take off on rapid, high flights around the immediate area, apparently not interested in conserving every last ounce of energy. After one such cold, windy feeding session, I had occasion to hand-capture one of the martins that had retreated to his cavity. I intended to band him, but he was already banded - yellow M096 - and I was surprised at just how warm and vibrant he felt after being outside flying around in these blizzard conditions. The martin had a yellow band with the code M096, and he was now six years old; I had banded him as a nestling at Moraine State Park.
Another lesson that was reinforced during this whopper of a cold snap was just how necessary it is to roust the martins from their housing to get them to feed. It became so cold that the martins refused to exit the housing even when I banged very hard and long on the pole. They must have instinctively sensed that there was absolutely no chance of finding an insect, and furthermore that the risk of exposure was greater that the chance of getting eaten by a pole-climbing predator. To scare some martins out, it was necessary not only to crank down the housing, but in several cases to shake the nest tray! Knowing that the long-term forecast was unrelenting, it was either force them out to feed or let them die. Since cranking a T-14 down and up is no small task, especially in freezing weather, I wanted to break certain martin's habit of staying inside until I lowered the housing, so, after several days, I took the opportunity to hand-capture and band these martins. Amazingly, they were in the air taking tossed food immediately after being released. However, after being banded, they rarely stayed inside after I started lowering the house.
One of the biggest surprises I encountered was Purple Martins arriving well after the cold weather had set in. It had always been my understanding that when the weather turns cold, migration grinds to a halt as martins hunker down wherever they are, attempting to save energy and "wait it out." While this may generally be true, several martins arrived after the onset of cold weather, suggesting that they were on the move when the weather was bad. Andy Troyer had his first martin - an adult female - arrive in Conneautville, PA (near Erie) on April 7 when the temperature was 24 F and there was 9 inches of snow on the ground. A third ASY-M arrived at Saxonburg Golf Course colony on April 14; he appeared healthy but was very hungry and immediately fed with the other two. A lone ASY-M arrived at the Moraine State Park colony site on April 7. Actually, he might have arrived on April 6, but I did not check that day after finding none on April 5th. The lesson learned was that martins can arrive even in the middle of a cold snap and may refuse to come out even if you pound hard on the pole. Therefore, it is necessary to check the housing every day if you want to save every martin.
All of the Purple Martins that arrived in southwestern PA in late March or early April of 2007 were biologically doomed when the cold front moved in on April 5, sending the temperature plummeting to an average high of 33.6 F for five consecutive days - 24 degrees below the normal high of 57.6 F! Purple Martins need a temperature of about 50 F to forage successfully, because large insects are not active below this threshold. The Purple Martins in southwestern PA would have starved to death during this period of cold weather unless they were receiving emergency supplemental feedings. 20 of the 21 martins at our colonies survived - defying the process of natural selection, perhaps - thanks to a handful of eccentric primates who chose to preserve them by flinging insects and scrambled egg into the air almost every day for two weeks.
Temperature Summary: Temperatures from April 5-19 averaged 17.1 degrees below the normal highs for that period: 42.2 F actual vs. 59.3 F normal.
Summary: During an extended period of cold weather that lasted from April 5 through April 18, 2007, PMPA staff members fed 20 Purple Martins that were already present at several colonies in the greater Pittsburgh area of southwestern PA. Food was flung into the air, placed inside compartments that martins were roosting in, or placed on feeding trays nearby. Surprisingly, several martins showed up well after the period of cold weather had begun. When the weather was extremely cold, several martins could not be scared out of the housing by simply banging on the pole. The housing had to be fully lowered and the martins scared out by shaking the nest tray. I was able to capture and band two martins as a result, and these martins began feeding immediately after being released. (The martins had been trained in previous seasons to accept supplemental feedings.)
As I publish this article to the web on April 25, 2007, there are 31 martins present at Saxon Golf Course, where on April 18 (one week ago) there were only three.
"April is the cruelest month, breeding lilacs out of the dead land, mixing memory and desire, stirring dull roots with spring rain" -T.S. Elliot