BLUEBIRD NARRATIVE 2018 FOR THE AUDUBON BLUEBIRD TRAIL (ABT)

Transcription

1 BLUEBIRD NARRATIVE 2018 FOR THE AUDUBON BLUEBIRD TRAIL (ABT) By Kent D. Hall, Ph.D., Coordinator The Audubon Bluebird Trail has completed 17 seasons of research on the Eastern Bluebird and associated cavity nesting songbirds (Tree Swallow, chickadee and wren). Based on successful total production of bluebirds (EABL s) per season, this effort has been the most successful bluebird trail in Wisconsin for the past 7 seasons and in the U.S. for the past 6 seasons. The 2018 season was the last one for our research effort, due to my failing health. A key to this project has been the project organization and the monitors associated with it. Based on my information, this project represents one of the more successful Citizen Science projects in Wisconsin Conservation history. Each week, from the start of the nesting season until no more E s are being laid by EABL s, monitors have sent me their data for each box (nests, eggs, chicks and fledglings). These data are then summarized and sent out in a weekly report (13-17 per season). At the end of the season, data are summarized for each route and a statistical report (see attachment) and narrative (as here) prepared for all routes (38 in 2018). This approach has proven to be one that motivates and retains monitors over time. This season, for example, we had 16 of 72 monitors who have worked with the ABT research project for 10 or more years, 5 for the 14th season, the entire time that monitors other than myself were used (I was the only monitor for the first three seasons). This season, our 72 monitors volunteered an average total of 50 hours per week for a total of 3,600 hours for the season. In addition, all paid their vehicular expenses and most repaired their boxes in addition to collection of scientific data. Weather is a major factor in successful nesting for birds in general. On April 15 & 16, 2018, the central and eastern parts of our ABT had a massive, historic snowstorm (1,073 boxes). This area averaged 20 of snow fall with 25 falling on our Scandinavian, WI, route. The Ft. McCoy area, where we had 282 additional boxes, only had 5-6 of snowfrom that storm. This snow storm caused the delay of nesting season in the eastern part of our trail by 2-3 weeks and at Ft. McCoy by about a week. Consequently, we produced only 4,035 fledged EABL s and only 60.7% of our boxes had E s laid in them, the 3rd worst in our history (after our first two years of operation 51.2% in our 2 nd season). Ft. McCoy is an exceptional area for bluebirds. In 2015 we averaged 7.01 fledglings per box out of 263 boxes and typically average between 5 & 6 birds per box. The numbers are usually the best productions in Wisconsin for trails of over 100 boxes. This season, we averaged only 4.78 birds fledged per box, but 0.67 per box were lost due

2 to black flies. Typically, we can control black flies, but two routes had them appear immediately after monitoring and could not do anything about controlling them. If you add the 4.78 and 0.67 together, one comes out with an average of 5.45 EABL s produced per box, quite similar to a typical season. So, the mild snowfall did little to control production in bluebirds at Ft. McCoy.. But, the 1,073 boxes in the eastern & central areas of our ABT, averaged only 2.6 EABL s fledged per box, only 54.4% of the 282 Ft. McCoy boxes. Our final production per box for our entire ABT averaged 3.07 per box, our 3rd worst average in our 17 year history. Only the 1.33/box in 2002 and 2.14 average per box in 2003 were productively worse (Table 7 in the 2018 statistical summary). Because of the severe snow storm and the late start to the season, the breeding season was shortened compared to previous years. Our 17 years of data show that the length of the breeding season varies with the time nest building begins in the spring and is not lengthened at the end of the season in August. If the season starts late, as in 2018, the time available for producing double and triple nests is reduced and both drop in numbers. For 2018, the number of EABL nests that produced double nests on the ABT was 28.7%, down from 52.6% in At Ft. McCoy, the percentage dropped to 44%, from a typical production of 60-70% and in the eastern portion of the ABT, it dropped to 19.3% from a typical average of 30-40%. Triple nesting was almost non-existent on the ABT in The Ft. McCoy area produced no triple nests (compared to 8 in 2017) and the eastern portion of the ABT produced 1 triple nest (compared to 0 in 2017). A bright spot in 2018 was a drop in the the total mortality (TM) for eggs and chicks on the ABT. We lost only 21.1% of our eggs (14.6%) and chicks (6.5%). This was one of our lowest TM s in our 17-season history. This represented a 2.2 loss of eggs for each chick lost. The usual loss of eggs is typically 3-4 times that of the loss of chicks. The higher loss of chicks this season was due to chick loss due to black flies at Ft. McCoy. Last season we lost 31.3% for TM. The extra percentage of eggs & chicks lost was due to higher egg lost due to cold spring weather. This season, there was little cold weather after the unusually severe snow storm. And neither was warm weather a problem, so there was little chick loss due to that cause. Tree Swallows (TRES): The major snow storm on April 15 and 16 did not prevent Tree Swallows (TRES) from nesting earlier or about the same time as EABL s. Typically, EABL s lay eggs 1-3 weeks earlier than Tree Swallows. By the time the snow storm hit, the rivers, lakes and ponds had lost their ice and insects were common over the open waters. With this food source available, Tree Swallows were able to occupy more boxes than normal and set an all-time record for our ABT with 2,368 fledglings. This number broke our previous record by 709. In 2018, there were 1.7 EABL s fledged for every TRES fledged, but 5.5 EABL s fledged for each TRES fledged in 2017 and for our 17-year study, we have fledged 4.0 EABL s for every TRES fledged. The 1.7 EABL s fledged for each TRES fledged in 2018, is a good reflection of how difficult a season it was for EABL s.

3 House Wrens (HOWR s): HOWR s tend to appear in central and western WI, about the same time each year (1 st week of May). Usually, EABL s already have hatched their eggs and have chicks in the nest prior to the arrival of wrens. This year, that was not true and HOWR s destroyed more EABL eggs than normal. The invasion of wrens was so bad that we opened many of our boxes for the season rather than produce a huge population of wrens (when wren s built cups or laid eggs in their nests, they were allowed to complete their reproductive cycles). A total of 290 HOWR s were produced in our boxes in 2018 (Table 2 in Statistics). Black-capped Chickadees (BCCH s): BCCH s are mainly permanent residents in WI, so they are prepared to nest when the conditions are right. But, when they choose our boxes, they apparently are choosing an inferior nesting situation. All of our boxes are in the open, away from trees (especially evergreens), the main habitat of BCCH s. So, in spite of nesting in 92 boxes, only 290 birds fledged from our boxes, an average of 3.2 fledglings per box. Since they lay an average of 6-7 eggs per box, they have ended up with a high TM. For 2018 that was 44.2% of all eggs and chicks. This high TM is typical for BCCH s in our boxes. A major source of TM for BCCH s is squatter nesting by EABL s and TRES s. We have eliminated that problem By placing square plates with 1 holes over the larger holes of the nest box, as soon as the BCCH has laid at least one egg. Since, even after adding this protective plate, the TM has stayed relatively high, we hypothesize that the very high TM in BCCH s is due to their selecting boxes with inferior habitats for successfully completing their reproductive cycles. Production by Individual Monitors: Bluebirds: In 2018, our ABT average was 3.07 per box with an average of 2.60 in our eastern area section and 4.78 in the Ft. McCoy area of our ABT. The top ten producing routes on the ABT (Table 3 of Statistical Summary) were 6.03 (Bruce & Jerri Brewer at FM, Monroe Co.), 5.89 (Gordy Weber at FM, Monroe Co.); 4,75 (Cathy Malzacher & Sharon Teske at FM, Monroe Co.); 4.28 (Warren and Janet Evans at FM, Monroe Co.); 3.92 (Clark & Wyleen High, Portage Co.); 3.91 (Mary Dahm and Sharon Schwab of Portage and Wood Counties); 3.76 (Tied: Ned and Mary Grossnickle of Portage Co. and Mike Moore of Portage Co.); 3.63 (Elizabeth Atwell, Marathon Co.) and 3.61 (Mary Bratz and Dick Stephens, Portage Co).

4 All Songbird Species: We averaged 5.25 birds produced per box for the 2018 season (includes EABL s, TRES s, HOWR s and BCCH s). This Average compares to the 4.88 average of The 2018 increase was largely due to the increase percentage of TRES s occupying our boxes. They average over 6 E s per box while EABL s typically lay 4-5 E s per box. The top 10 routes for average number of songbirds produced for 2018 were: 6.71 (Samantha & Wendy Carlson, Portage Co.); 6.66 (Bruce & Jerri Brewer at FM, Monroe Co.); 6.49 (Ken and Megan Karth, Waupaca Co.); 6.42 (Clark & Wyleen High, Portage Co.); 6.00 (Tied: Bill and Jan Seybold, Portage Co.; Gordy Weber, At FM, Monroe County and Bill and Jill Ziehr, Portage Co.); 5.96 (Mike Moore, Portage Co.), 5.88 (Alice Chaney &Melba Carey, Waupaca Co.) and 5.82 (Fred and Joyce Camancho, Portage and Wood Counties). Miscellaneous Data: For 13 seasons we have recorded the number of white eggs laid and the number of eggs laid per box on our ABT. In 2017, we had 182 white eggs laid out of our 5,113 total = 3.6% of the total. This figure tied our best-ever percentage of 3.6% in The 5,113 eggs laid averaged 3.89 per box, the lowest in our 13 seasons. Problems encountered and counteracted (where possible) this season. 1) Weather: Nothing could be done about the major snow storm that occurred on April 15 & 16. But there was considerable rain last season. We countered the rain by carefully caulking our most vulnerable boxes. Our effectiveness was confirmed because we lost very few nests due to wetness. 2) Woodpeckers: Very few boxes were lost due to woodpecker damage and those that were damaged were mainly reparable with silicone caulk. The best preventive measure to prevent woodpecker damage that we have found is wiring open boxes in fall, winter and early spring. The light and circulating air are deterrents to woodpeckers that commonly use boxes as roosts during the winter months (especially Hairy Woodpeckers). 3) Blackflies: The only area that has proven to have problems with black flies is Ft. McCoy in Monroe Co. The slow-moving, LaCrosse River annually produces an abundance of black flies. Black fly females attack birds and mammals for blood meals. The cuts from the flies can drive incubating females off of their eggs causing death due to cooling and can kill chicks due to these cuts. Last summer, two routes were attacked by black flies. Both routes lost numerous chicks. Our usual criterion for starting a spraying regimen of Permethrin was the appearance of a few black flies around our boxes. None appeared prior to the loss of chicks on these two routes, so in the future we will use a different approach. Spraying will start the last week of May, a time that has proven to be the earliest time black flies appear on the Ft. McCoy property. 4) Raccoons: Raccoons were a minor problem on our routes in They were largely controlled by these techniques: a) Lubrication of ¾ conduit and predator guards with petroleum jelly or other lubricants b) use

5 Of 6 ½ noel guards or Slinky s (on ¾ conduit, was 100% effective on a 31 nest box route). 5) House Sparrows (HOSP s): HOSP nests continue to drop on the ABT. In 2016 they occupied 42 boxes, 30 in 2017, but Only 26 of 1,315 boxes had HOSP nest attempts in them this season. This is an exceptionally low number for a trail of the size of the ABT. We feel that this number reflects our choice of locations for song birds and our highly successful HOSP trapping with Van Ert traps. We continued to show that trapping is typically necessary for only one or two rogue birds and then one of our four major songbirds build a nest and usually fledge young. 6) Bears: Each season we lose several boxes/posts to bears at Ft. McCoy. Eggs and chicks are just too enticing for some bears to pass up. They often bend over our posts to more easily get to the boxes. The boxes present no problem to the bears as they can easily crush them to get at eggs & chicks. Since this problem is one unique to Ft. McCoy, we have learned to live with it as a necessary part of working in a semi-wilderness environment. MY PASSAGE: For 17 years a large part of my life has been devoted to the conservation of the Eastern Bluebird and other cavity nesting songbirds. The support I have received for this project is simply remarkable. This is my last annual report for the ABT and I want to thank those who have helped make it a success. I hesitate to select just a few people to thank, but their extraordinary effort dictates that I do so. First in this group of exceptional people is my wife, Sue. She, more than anyone, has supported me in this dream of my life. As is typical of Sue, she not only supported me, she wanted to join in the fun and had me develop her own route. For 14 seasons she has monitored her own route of boxes. Sue has recruited co-monitors for her trail during that time, including Tricia Schaufenbuel, Cassidy Crunkilton and Dianna Mrozinsky. It is safe to say that this project would not have accomplished as much without Sue s dedication and support. Next on the list is Bob Lane. With an address of Aldo Leopold, Jr., how can you go wrong with this guy? My respect and appreciation for this man is enormous. Bob is the only one that has remained active with the ABT Project for its duration, other than my wife and I. Bob is a man of many talents a true handyman. Professionally, he was an educator and spent many years as an Administrative Principal in several different school systems. For the ABT, he was the lead carpenter and trouble-shooter. He supervised the construction of 3,900 nest boxes for the ABT and more than 100 other bluebird trails in Wisconsin. Moreover, he helped with the development of trails around at least three elementary schools, took on problem solving when we encountered challenges on the ABT and so much more. First and foremost, this is a good man. His value system is one of true belief in the innate beauty of nature and humanity. Without him, this project would never have happened. The final person I want to thank is John Munson. John has been there for so many things. Chief among his skills are fund-raising and carpentry. When we were struggling with finding $$$ for the ABT, he suggested we have people sponsor bluebird boxes for a given price. We were able to raise enough money to get the project off the ground until money could be obtained elsewhere. Luckily, Audubon now has an endowment that

6 has helped supply the bulk of the $12,000 that has been used to develop and maintain the ABT for 17 years. John has also helped construct nest boxes and other building projects, as needed. One thing for sure about John Munson is his value system that includes a deep appreciation of nature and the respect for humankind. Of course, members of the Aldo Leopold Audubon Society Board and Committees have been very supportive in many ways during the 17 years of ABT development and maintenance. I thank them all for their support. And, where would we be without the 153 monitors that have checked boxes all of these years? Their sacrifice and dedication have been inspirational to me. Working an average of 50 hours a season, paying for their transportation and supplies, and getting their data to me weekly and at the end of the season, has been extraordinary. Bottom line is, EABL populations are now in the best condition in decades: BECAUSE OF THEM. With thanks, Kent D. Hall Coordinator, ABT