The 2017 monitoring season of Highland County American Kestrel Nesting Boxes started with the first monitoring round on April 16. The regions of Highland County are divided into parts, one consisting of the Blue Grass Valley (BGV) boxes which is the core story area of the Blue Grass Valley Monitoring Project, and the other consisting of the remaining boxes in the county which are not located in the Blue Grass Valley. There are 38 boxes in the BGV Study and 14 in the rest of the County.
The boxes within the BGV study area are monitored more frequently at an interval of every 10 days or so, and they are cleaned out at the end of the season. Cleaning out the boxes and examining their contents can reveal much about what happened inside that box. By examining eggs that are non-viable and by analyzing the contents of the box and examining pellets inside the box, you can learn what prey the birds were eating, what remains are left in the box and possibly what happened to eggs that did not hatch. Also, we are providing next year’s box occupant with a cleaner box, removing dead debris and placing new wood chips in to prevent rolling eggs.
Of the 38 boxes in the BGV study area, 15 of them (or about 39%) produced fledglings. I approximated by visual observation that these 15 boxes produced 56 birds, which is a low estimate. Without actually seeing the young birds after they fledged, it is impossible to come up with an accurate number, but this approximation yields about 3.7 birds per box. It is important to remember that number of birds fledged does not represent number of birds that survive and reproduce the following year.
Here is a table of results for the remaining boxes, some of which were empty, some used by other species, and some predated. Some also just were abandoned or failed to produce eggs that hatched and one can only speculate in many instances as to why this occurred. Note that some categories overlap and therefore the total exceeds the number of boxes.
The surprise, and a negative one at that, is the number of abandoned boxes after eggs were laid. I have no idea why this occurred and can only speculate. It is possible that the birds were harassed by starlings or some other predator, the adult(s) were killed, there were temperature extremes which may have affected successful hatching or some other reason. Four out of the 5 boxes were located within 6 miles of each other on the same road, and three of these boxes were successful last year, so perhaps some disturbance occurred along that road. It seems more than a coincidence that all of these boxes were inhabited, and then abandoned.
Another interesting an unexplained event is that the breeding season ended about 2 weeks earlier than 2016. By mid June of 2017, there were no boxes with young kestrels. In 2016, I monitored into the first week of August.
One reason for the change in dates of box occupancy could have been weather related, so I collected weather data from weather observers, both at high elevation and in the valley.
|Category||# of Boxes||% of Boxes||Occupied by AMKE||24||63%||Boxes That Produced Fledglings||15||39%||Number of AMKE Fledge (Estimate)||56||-||Number of Kestrels Fledged per Box (Average)||3.7||-||Empty Boxes||2||5%||Starling (Never Occupied by Kestrels)||5||13%||Bluebird (Never Occupied by Kestrels)||3*||5%||Eggs Totally Disappeared||1||2%||Eggs Predated By Starlings||3||8.5%||Eggs Predated, Unsure of Who||2||5%||Eggs Abandoned||5||13%|
|* One box occupied by bluebirds later in season after used by starling.|
In February of 2017, over half of the days had temperatures in the fifties and sixties, quite a warm month. This may have caused the kestrels to claim the boxes earlier and perhaps lay eggs earlier. In March of 2017, there were over 6 days where the temperatures ranged in the low teens. In April, from April 1 to April14, the temperatures remained in the forties, with several days of below freezing temperatures and snow. This may have had an effect on incubation, especially if the male had to travel significant distances to obtain food to feed the incubating female.
Clutch Initiation Date (CID) is exactly what the name implies: the date that the first egg is laid. All of my CIDs are estimates, but the earliest Clutch Initiation date this season was April 18 and the latest was May 30. This late date was most likely a second attempt to incubate, probably by the same pair, after starlings took over the box after AMKE eggs were laid. The majority of clutches were initiated from around April 14 until around April 24.
One note of interest is that a female banded in the winter of 2016 occupied and successfully nested in a box less than one quarter mile from where she was banded. I conclude this female is non-migratory.
In conclusion, the occupancy rate is high for the Blue Grass Valley study area, although slightly down from the 2016 season. The area outside the valley also had more AMKE occupied boxes. Of interest are the number of boxes that were either abandoned or predated this season. This was the first season that detailed records were kept with regular monitoring intervals. It will be interesting to see what occurs in the 2018 breeding season, the second year of this project. Next season, we will look for possible causes for why boxes were abandoned or predated. We will keep detailed records of observation of all boxes in 2018.
Written By: Patti Reum, with help from John Spahr, Doug Rogers and Keith Carson
Each year hundreds of millions of birds are killed by collisions with windows on homes, businesses, university campuses, you name it! Any structure with reflective glass represents a potential hazard for birds. Today, most ornithologists agree that window collisions kill more birds than any other anthropogenic cause other than of habitat loss. At this time of year, birds are especially vulnerable to collisions with windows, as young birds are making their first perilous trek toward distant wintering grounds in the southeastern US, Caribbean, Central and South America. On this journey, they must navigate through many manmade landscapes offering numerous opportunities for window collisions. The good news is that this is an issue we can do something about…
Researchers at Virginia Tech’s Conservation Management Institute have launched a crowdfunding campaign to support research focused on understanding and mitigating the impact of window collisions on bird populations. Funds raised by this campaign will support student research experiences for natural resource majors at Virginia Tech. This campaign seeks not only to better understand a pressing conservation issue, but to provide opportunities for students to gain practical experience in wildlife conservation research. Using study sites on the Virginia Tech campus and suburbs of Blacksburg, students will assess where, when, and why birds collide with windows, as well as methods for preventing collisions.
Most of us can relate to the experience of hearing a bird thud into the windows of our home or office and wonder what we can do to prevent such occurrences. While resources are available from sources like the American Bird Conservancy (see https://abcbirds.org/get-involved/bird-smart-glass/), too little is known about window fatalities from low-rise structures in small towns, cities, and suburbs. Every donation made to this project between October 2nd-November 10th will be a step toward better understanding this issue and funding student research experiences. Please check out the project website (https://crowdfund.vt.edu/bird_window) and consider making your own contribution today.
Temperatures continue to drop, as Autumn arrives and we wrap-up the first season of the second Virginia Breeding Bird Atlas (VABBA2). Two things stand out about this summer’s field season. First, Virginia is an incredible place to survey birds. Between the mountains and valleys, the rolling Piedmont, and the rich Coastal Plain, Atlas volunteers identified over 205 species of birds and confirmed 174 of those species are currently breeding. They reported over 684,000 birds to the project!
Interestingly, most of the data received this year comes from areas where the most people live. This makes sense! We tend to bird the areas closest to home first. However, just think what kind of data will be generated when volunteers expand out into the less birded parts of the state. There are so many awesome breeding records just waiting to be confirmed in the rural Piedmont or out in the mountains or even in your own neighborhood.
The second remarkable thing about this first season is the volunteer birder community that pitched in from all over VA. By the end of the summer, over 450 volunteers contributed to the Atlas project and despite most data coming from populated areas, volunteers reported great breeding data from many rural parts of the state.
Everyone experienced some sort of learning curve, whether it was using eBird to report their data or learning the codes to document bird behavior. Many volunteers are still new birders and learning much as they go along. However, Atlasers collectively demonstrated that learning these new tools is doable and worthwhile. This first year would not have been a success without these many dedicated volunteers. We thank them for all they’ve done to contribute and promote birding for conservation with the VABBA2.
Exciting new project updates are on the horizon for our next field season. Cornell has now upgraded eBird mobile and volunteers can enter all field observations for the Atlas (including breeding codes!) with their smartphone! Additionally, there will be a series of Atlas Training events this Spring, focused on both field and data entry methods. Stay tuned for these and other field trip or training events in your area.
We’re also looking for project feedback from existing volunteers, as well as those who aren’t yet involved with the project. Please follow the appropriate link below to complete a quick survey about the project.
Current Atlas volunteers: 2016_AtlasVolunteer_Survey
General public: 2016_AtlasGeneral_Survey
Use the winter to learn eBird or the project breeding codes or to work on honing your bird ID skills. Most of all, get pumped for season two in Spring of 2017! Bird on, Virginia!