RHWO History at CCESR 2010 – 2016
2016 Summary
Dr. Jim Howitz, RhWR Research Team
As 2016 began, 72 Red-headed Woodpeckers were present at the Cedar Creek Ecosystem Science Reserve (Cedar Creek). This is the highest number of overwintering birds, since we began intensively studying the birds in 2012, and possibly ever. The northern pin oak acorn crop at Cedar Creek in 2015 did not appear impressive, but we saw birds harvesting and storing acorns in late summer and fall. The birds engaged in flycatching whenever the weather allowed insects to be in the air. It appeared that after the temperature dropped below freezing, the birds relied exclusively on stored acorns. The birds presumably benefitted from the strong El Niño, with consistently above normal temperatures throughout the fall and winter. About 83% of the birds present in the fall of 2015 were present in the spring of 2016. We were surprised by the number of new birds that showed up in the spring. With the overwintering birds and new birds, we had 54 breeding pairs, up from 35 pairs in 2015. The breeding season felt much like that of 2012 when we had 57 pairs. The 73 fledglings produced were a record. With about 180 adults and fledglings present in the savannah, the birds appeared to be everywhere.
The trend of having fewer pairs in the east part of the area and more pairs in the west part continued in 2016. The many prescribed burns have left few live or dead trees along Durant or Fish Lake and there were fewer nests there than in the past. More birds nested west of East Bethel Boulevard than ever, in areas where the prescribed burning was begun just a few years ago. One male moved over a mile from where he nested in 2015 near Fish Lake to just west on East Bethel Boulevard where he nested in 2016. We expect similar movements if the current burning regimen continues. Oak wilt continues to kill northern pin oaks, especially in the unburned woods. As these trees die, they could provide nest sites for the birds for many years. So Cedar Creek should continue to have breeding Red-headed Woodpeckers, though there may not be as many where are used to seeing them.
Then, as in 2012, all the birds disappeared in August. In 2016 we noticed almost no acorns. With nothing to eat in winter, the birds presumably have gone to where acorns or other foods are present. So, 2016 and 2012 have been similar, with many birds that attempted to overwinter surviving to the breeding season, a high number of breeding pairs, a poor acorn crop, and no birds remaining after late summer. Based on 2012 – 2013, we expect fewer breeding pairs in 2017 than in 2016, but that significant numbers of birds will be present in fall and winter 2017. But who knows?
Redheads Return
By Dr. Jim Howitz, RhWR Research Team
Only two Red-headed Woodpeckers overwintered this year at the Cedar Creek Ecology Science Reserve (Cedar Creek). The first of the woodpeckers that spent the winter elsewhere returned by May 1. However, we kept noticing “new” birds throughout Only two Red-headed Woodpeckers overwintered this year at the Cedar Creek Ecology Science Reserve. These birds appeared in areas where we were sure no Redheads were present earlier in the season. So, our initial nest surveys underestimated the eventual size of the breeding population. This is the first year when we have been convinced that new birds arrived weeks after the beginning of the breeding season. The newly arrived birds generally were SY birds (birds in their second calendar year and first breeding season). They may have failed to find a mate someplace else or been unable to find a suitable territory. At least five of these birds found a mate at Cedar Creek and began a nest. It appears that Red-headed Woodpeckers in their first breeding season may still be seeking a territory and mate while other Redheads have nestlings or fledglings. Since Redheads can still have active nests in September, these latecomers should have time to nest successfully.
2014 Report Season’s Studies
By Brittney (Larson) Yohannes, MS Candidate, University of Minnesota
My favorite part about field research is not knowing what I will encounter on a given day of work. My natural curiosity goes wild every time I see a hole in a tree. Looking inside those unassuming holes is like playing “Let’s Make a Deal.” I investigate each hole with great anticipation for what it hides. An old, dry snag looks so barren from the outside, but can cradle so much life inside its hollow trunk.
This summer my field assistant, Laura Jaskiewicz, and I have been exploring the nest cavities of Red-headed Woodpeckers living at Cedar Creek Ecosystem Science Reserve in East Bethel, MN. Under the direction of Dr. Todd Arnold and Red-headed Woodpecker Recovery, we are using a color camera mounted on telescoping pole to monitor over 30 nests and are archiving photos and video of each stage of the nest process. From mid-May through the end of July we have already taken over 3,200 photos of over 60 cavities in trees (some belonging to critters other than Red-headed Woodpeckers). Three days a week we peer into each Red-headed Woodpecker nest cavity to see how each brood is progressing, monitoring changes and recording success rates. Although the nesting season is still active, our early observations from the 2014 season show that about 85% of the nests have fledged at least one juvenile. This is a slightly higher success rate than in 2012 and 2013, which were closer to 80%.
Previous research had indicated a typical Red-headed Woodpecker pair has fewer babies fledge from the nest than they originally laid eggs. My research has been partially focused on gathering evidence pointing to brood reduction and observing possible causes. Of the 15 nests we monitored from egg laying through successful fledging, all of them lost at least one egg or nestling in the nest. Although many pairs laid five or even eight eggs, a month and a half later at the time of fledging only two or three nestlings remained alive in the crowded cavity. We continue to pursue the cause of this brood reduction. Many hypotheses remain, including infertile eggs, sibling competition, and parasitism.
By simply taking the time to look inside the nests each week we have already seen things we did not expect, including eggs not hatching, a nestling seemingly bleeding from insect bites, and nestlings that are considerably less developed than their siblings. Most photos we take lead us to ask more questions about brood reduction, and occasionally suggest an answer. My hope for this and next summer is that by observing the often hidden nest habits of these birds with our nest camera we can learn more about brood reduction. This will provide the key to understanding why their population is in decline.
2013 Continuing Studies
By Jerry Bahls, RhWR Communications, Dr. Jim Howitz, RhWR Research Team, Siah St. Clair, RhWR Research Team
Patrick Hartman (lead researcher) and Alan Watchuka, Advanced Placement Environmental Science Teachers at St. Louis Park Senior High School, conducted research on Red-headed Woodpeckers at Cedar Creek Ecosystem Science Reserve during the summer of 2013. They studied them by monitoring their nests using a newly acquired, capable of being put into the nest hole, mounted on an extension pole, capable of extending to 40 feet, to peek into the nests to determine when they laid their first egg, how many eggs were laid, when they hatched, how many survive and how many fledge. By diligently monitoring 20 of the 23 nests located during the year, greater knowledge was obtained that will help in their long term population increase.
Because Pat and Al were funded through an education grant to Cedar Creek Ecosystem Science Reserve (CCESR), they were able to bring some of their students out to CCESR to observe their work. The cavity camera used by Pat and Al gave a new ‘look’ into the life of our birds. An example: we have always known that our RHWO nest were often in small diameter cavities and, from what we could see in terms of fledging, it looked like they were only laying one or two eggs and fledging one or two young. The camera revealed that the birds are indeed laying clutches of four to five eggs and fledging younger than we expected. Pat and Al’s students helped to analyze the data that they collected and consequently had experience observing data collection followed by data analysis.
Late in the summer of 2012, the RhWR observers were busy watching the Red-headed Woodpeckers attempting to raise second broods at the CCESR and so were slow to notice that most of the birds were gone. The acorn crop was virtually nonexistent and this was likely the primary reason that the birds migrated. The last woodpeckers to leave were the two pairs that raised two broods. While about 120 Red-headed Woodpeckers were present during the 2012 breeding season, none were at CCESR from early September 2012 to May 2013. For months the savannahs, woods, marshes, and fields where redheads had foraged were eerily devoid of the life that the iconic birds had brought to the area.
The first red-headed woodpeckers returned on May 9, 2013. More woodpeckers appeared to arrive the next two weeks. On average males returned 4 days earlier than females, but this difference was not statistically significant. Birds breeding for the second time (SY) returned on average 6 days later than older (ASY) birds and this difference was statistically significant.
The return of the woodpeckers gave the first opportunity to estimate the birds’ annual survival. The Red-headed Woodpecker account in Birds of North America cites a survival rate of 62%. There were fifty adults color banded in 2012. Of the 50 color banded birds, 33 were seen in July or August 2012. Two were found dead along Anoka County Road 26 and several others probably died during the breeding season. None were seen after September. So about 33 color banded birds migrated elsewhere in late summer. In 2013 only 17 color banded birds returned. That would give a poor survival rate of 34%.
In 2012, there were about 60 pairs at CCESR. In 2013 only 32 pairs were observed. What could account for the nearly 50% decrease in the number of breeding woodpeckers? Presumably, migration holds hazards that birds remaining on the breeding grounds don’t experience. So, some additional mortality would be expected. It could well be that some of the color banded birds are alive and well elsewhere. It is hoped that some will show up at CCESR in coming years.
All the male woodpeckers that returned in the spring of 2013 returned to the same territories as in 2012 or moved just one territory. Of the six females that returned, two returned to the same territory (and the same nest), two moved one territory, one moved three territories, and one moved four territories, that based on this small sample, it appears that female red-headed woodpeckers are more likely to move a significant distance from their previous year’s territory than are males. This is typical of birds. In birds females generally disperse farther than males.
Only two pairs returned which had both birds color banded. These nested in the same holes as in 2012. Of the 17 color banded birds that returned in 2013, two of the birds were a surprise. These were birds caught early in the 2012 breeding season and no nest nor mate was observed in 2012. They may not have been noticed or they may have gone elsewhere during the breeding season.
In 2012, 80% of nests fledged at least one young. Thirteen of seventeen returning birds fledged at least one young, two birds nested and failed to fledge any young, and no nest was found for the remaining two.
In 2012 of the fifty color banded birds, ten were second year birds (birds in their first breeding season). So far in 2013, only two of sixteen birds we have banded are second year birds. So, in 2012, about one-fifth of the population were “new” birds, but in 2013 very few birds are “new”. The number of nests at CCESR increased from about 42 in 2011 to 50 in 2012. The extra 16 birds could have been older (ASY) birds from elsewhere or (more likely) SY birds hatched at CCESR or from distant nests. If only one-fifth of the birds were SY, some ASY birds must have moved to CCESR from elsewhere. In 2013, the many unbanded birds are nearly all ASY birds. Presumably, all or nearly all of these were present in 2012 and were among the approximately 70 birds that did not get banded. A major factor in the decrease in population in 2013 appears to be a minimal recruitment of SY birds.
2012 Completed Research
By Jerry Bahls, RhWR Communications
In the summers of 2011 and 2012, the Red-headed Woodpecker Recovery (RhWR) has provided funding for research conducted by graduate student, Ari Waldstein (below), at Cedar Creek Ecosystem Science Reserve. Ari’s work has contributed valuable new information to our knowledge of the breeding biology of Red-headed Woodpeckers.
In the summer of 2012, Ari and her sister, Sasha, used our nest camera to take videos of nestling red-heads almost ready to fledge. It was quite difficult holding a swaying 30-foot pole with a tiny camera on the end and inserting the camera into the nest cavities, but they succeeded.
The photos below are video stills of Ari and Sasha using the video camera, and of eggs and babies inside nest cavities. Click on this link to see the videos at YouTube.
Previously, we had suspected the average clutch to be only one or two birds, given how small in diameter most nest limbs were. But Ari’s research revealed between three and four young crammed into most cavities. That was quite a surprise. And that’s what research is all about!
Committee members also contribute to the research by searching for nests at Cedar Creek Ecosystem Science Reserve. In 2012, they were able to confirm 42 active nests. That’s the most ever! And a big increase over 2011.
2011 – A Bird in the Hand….
By Jerry Bahls, RhWR Communications
Toward the end summer 2011, Ari successfully trapped and banded an adult Red-headed Woodpecker (right). This was our first banded bird! Nicknamed “Eve”, she was captured in Burn Unit 401 not far from Highway 26. Eve was banded with yellow and blue plastic bands on the left leg and red and silver bands on the right leg. The color banding program is continuing.
