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American Kestrel Nest Box Project: Year 4 in Review

July 31, 2019 Category: ,
One of the “kids” from the boxes this season.

It is hard to believe that another year of American Kestrel nest box monitoring has come and gone in the Sax-Zim Bog! This was a season with a number of surprises, records broken, and excitement for the future! If you are not familiar with our project, here are a couple of Bog Blog posts to get you caught up: (2016 and 2018).

Pre-Season 2019

Each kestrel monitoring season usually starts in the first week of May up in the Sax-Zim Bog. But what about what happens before our volunteers head out in the field to check on the boxes? Boxes need to be cleaned, repaired, or adjusted prior to the arrival of the kestrels! On April 19, myself and new kestrel monitoring volunteer Victoria Harthorn started the 2019 monitoring season by cleaning out old boxes and taking notes of each box’s condition. This step in monitoring is incredibly important… and time consuming! But, if we want to continue the nesting success we have had in the Sax-Zim Bog it must be done.

Much to our surprise, kestrels were in the Bog in really good numbers (we saw nearly 2 dozen through the day!). As exciting and surprising as that was, much of the excitement came not from kestrels, but from what was found in their boxes! We found a few expected things (bones and pellets from the year previous, unhatched eggs, etc) and a few unexpected things, most notable being a kestrel box nearly full to the brim with grass. As I was pulling grass and fluff out of the box, a meadow vole promptly leapt out of the box and on to the grass below. There was the culprit… or so I thought! I continued to pull out grass and the second occupant, a white-footed mouse decided to crawl up my arm and on to the telephone pole before scurrying away through the grass! Both of these rodents had climbed nearly 15 feet up a telephone pole to create a tidy winter retreat in one of the boxes. Wow!

Here is the pile of grass and fluff compiled by the meadow vole and white-footed mouse from the story above! Those two were busy creating a warm home over the winter!

All of that is quite exciting, but perhaps the biggest surprise was the fact we had kestrels sitting on eggs…. on April 19! And not just one box… 3 boxes were occupied by female kestrels, with at least two sitting on eggs! Prior to this, the earliest we have had kestrels on eggs was May 7. Things were looking good and monitoring had not yet started!

Monitoring Year 4

If you recall from prior blog posts, there are 36 American Kestrel nest boxes scattered through out the Sax-Zim Bog. This season, we ended up having 13 boxes occupied! This is one more box occupied than last season. Similar to last year, and actually every prior year, there were nest failures. Two of the thirteen occupied boxes this season failed (one nest was predated and one was abandoned), meaning 11 of the 36 boxes in the Sax-Zim Bog were successful! From these 11 boxes, we were able to band an eye popping 51(!) chicks. Our first set of chicks were banded on June 8th (2 beautiful chicks from the box with eggs on April 19!). The last 5 chicks were banded on July 18, just a couple of days prior to the BioBlitz. With this nesting success, we were able to break 100 banded chicks! To date, we have banded a total of 131 chicks in the Sax-Zim Bog.

This monitoring season saw a few extra things happening during chick banding. While we had chicks out of their box, we would collect pellets and any prey remains, as well as poop from inside each box with chicks (or straight from the nestling kestrels if they were so gracious to give us some!). The poop, pellets, and prey remains will be used as part of an upcoming graduate thesis at the University of Minnesota-Duluth, which will be looking at prey selection for American Kestrels. As part of another study, we would also collect a couple of chest feathers from the most developed chick in each box. These feathers will be sent out to Idaho for a project based in Boise which will be looking at the genetics of American Kestrels across the United States. It is very exciting to be a part of these studies!

Looking Ahead to Monitoring Year 5

Our work is never really finished in the Sax-Zim Bog and even as we are wrapping up data entry to the American Kestrel Partnership website, plans are already being made for Spring of 2020!

Some of that work that will be completed in Spring 2020 is able to happen due to our membership, which has come through by making and donating nest boxes! With your donations, we are able to add to our total and reach 50 nest boxes in the Sax-Zim Bog AND we are able to replace a couple of older boxes with the extra boxes donated. We are grateful to those folks who have made and donated kestrel nest boxes to this project! In March of 2020, these boxes will be going up and we will be cleaning out and repairing boxes, preparing for the arrival of kestrels back to the Sax-Zim Bog.

A volunteer’s eye view of one of the 36 boxes in the Sax-Zim Bog.

With all of these new boxes, we will be needing volunteers. This is usually the place where we would call for volunteers, but that isn’t the case this season as our stellar kestrel monitoring crew of Mary Gabrys, Jean Elton-Turbes, Sarah Beaster, and Sally Grames was joined this season by Victoria Harthorn and her husband Kim and will be joined (hopefully!) next season by Jeri Schwerin. Without our volunteers and their time spent, this project would not be as nearly as successful as it has been the last four years!

The last major project on the horizon is a pipe dream currently, but would be an incredible project. Frank Nicoletti, who established this monitoring program and who is the head raptor bander at Hawk Ridge Bird Observatory, is very interested in color banding adult American Kestrels in the Sax-Zim Bog. Color bands are those brightly bi-colored bands, often seen on Peregrine Falcons or Piping Plovers, allowing an observer to identify individual birds from a distance and does not require recapturing of a particular bird for it to be identified. These bands would be useful in determining if adult kestrels are coming back to the same nesting locations, to potentially see where these birds end up in the fall and winter months, to figure out where they might be going while they are in the Sax-Zim Bog, to investigate territory sizes… the list goes on! This project could happen as early as next spring, but funding needs to be secured to purchase color bands.

Buckets are a safe way to transport and contain kestrels before and after banding. There are five chicks in this bucket… can you find them all?

This year’s monitoring efforts added important and valuable data to our understanding of American Kestrels in the Sax-Zim Bog; will be adding to the understanding of American Kestrels on a wider scale; and was certainly a season to be remembered for its many successes! I want to thank Frank Nicoletti for his continued support of and excitement for the project, as well as his time spent coming up the Bog to band chicks; I want to thank Mary, Jean, Sarah (and her daughters!), Victoria and Kim for their volunteer efforts this season; I would like to thank all of the folks who donated boxes this season, and during the first call for boxes; and I would like to thank all of the interested folks in the Sax-Zim Bog who have taken a moment to talk to our volunteers (or myself) when we have been out in the field and monitoring these nest boxes.

Volunteer Mary Gabrys with a close look at one of the newly banded chicks!

Stay tuned for further reports and calls for volunteer help regarding this project and until next time… I will see you in the Bog!

– Head Naturalist Clinton