Yellowstone Reports

Printer-friendly version

Boreal Study

One Last Week (finishing up)
by Dan Hartman

May 1, 2022

     For this last week of my boreal owl study I was joined by professional birder Gary Zylkuski.  He had traveled all the way from New York not only to learn about these little owls,but also to rejuvinate my waining energy for the project.
     Right away, we were out Sunday night, hiking out to an over-look, hoping to fine tune the location of the boreal at Post#4.
     We were just approaching our destination when an eerie call drifted up from the trees just below us.  It lasted 8-10 seconds and was not repeated.
     An alarm call?
     Eventually, we left to start the owl run.  By the time we finished we had heard 4 songs, including our boreal at Post#4.  But now he had moved farther west.
     The next day, we walked and waded through snow to search the area around Post#4.  By the end of the exhausted trek, we came up with only one likely nesting cavity.  However we could only cover half of the territory because of the snow depth.
     We were out again that night for one last time. (Wind cancelled out Tuesday night, rain and snow made the rest of the weeks nights impossible.)
     At Post#1 A boreal called just to our west, the second night in a row we've heard him.
     Post#1.5 was silent and has been since the first after 14 songs have ben heard.
     Post #2 was also silent with only one song heard all season.
     Post#3  A boreal was calling across the creek.  Only the 4th song this season.
     Post#3.5 was quiet but we have heard 9 songs from here including one last night.  Just down the road a mile, we've been hearing another boreal just starting to sing lately.   And he was singing tonight just to the SW.  The 7th time we've heard him.
     Post#4  Was silent.  This was surprising after the 2 calls we heard last night.  He's called 17 times this season.  I think even though we found very little in our search earlier in the day, it's still a good bet a nest is here to find, after the snow melts.
     The other boreal that called to the south has been silent since the 1st.
     Just up the road another boreal has startd up lately and has called 7 times since the 7th.  He sang again tonight, far to the NE.
     At Post#4.5 A boreal sang fairly close from the north.  This is another owl that has just started up lately, and has called 5 times.
     At Post#5 once again another recent boreal was singing.  His 8th time this month.  Also a saw-whet owl.  His second night in a row.
     At Post #5.5 another late arrival has called 4 times but has been silent lately.  And was also silent tonight.
     Post #6 was silent and has sang only 3 times all season.
     Post#7 also silent.  It called 3 times in early March but then fell silent.
     Post#8 Our cabin.  This boreal has been a puzzle.  He sang 8 times in March, but we've heard nothing since .  We have had a saw-whet calling nightly and a pygmy whistling daily.
     A mile down the road a boreal started up recently and sang 3 nights, but has fallen silent.
     So 6 calls in all.  Not bad for the 25th of April.
     Research in Scandanavia has found, late season singing boreals are mostly juveniles and rarely attract females.  We seem to have several of these this year.
     Also, Gary found research that stated males sometimes get a female situated at a cavity early in the season, then move a short distance and try to attract a second female.  Quite often successful in Scandanavia, but rarely in North America.  That seems to match what we've found at Post#4.
     The next day, Gary and I hiked down into Hell Roaring where I've found a variety of owl nests in the past.  We found white wash and pellets early, but nothing of significance otherwise.  At least we didn't have to deal with snow.
     Wednesday, we crossed the creek and searched for Post#1.5's nest site.
     This was actually my most consistantly signing owl the month of March. But fell silent after singing one last time on April 1st.  This should mean he had found a female and they had picked out a cavity.
     After all, he called 12 times.
     We located 2 cavities which I had scoped earlier from across the creek.  However, neither showed sign of usage.
     Then Gary discovered the remains of a dead clarks nutcracker.  He called me over to check it out, then noticed another clump of bird remains.  Both birds were incased in snow and ice.  What I saw was as Gary supposed, the carcass of a clarks nutcracker.  But the seond clump of feathers were very different and I recognized them immediately.
     There were my boreal owl!!!
     Now we know why he quit calling three weeks ago.  What a sad discovery.
     I continued to search on, and happened to stand just right to spot a hidden cavity some 35-40 feet high in a fir.  It was a classic boreal nest site.  It's frustrating to know it'll be empy this year.
     Gary and I searched a couple areas the next day, but were really limited by the 2 feet of soft snow.
     This officially ends the boreal owl study.
     Lots of ups and downs brought on by the unusual spring weather.  lots of wind, snow and cold.
     In the end, I did hear a record 102 boreal songs.  Topping the 95 I heard in 2015.  Also 7 saw-whet calls, 5 great horned hoots and a dozen pygmy whistles.
     Finding the dead boreal owl was not a fitting ending to an otherwise great season.  A nice rebound from the previous 6 years. 
     I will check out other locations in my study area as the snow melts, probably later in the month.
     Note:  As to the cause of the little boreals demise.
     Did he kill the clarks nutcracker, then was mobbed and killed by the nutcrackers friends?
     Did they kill each other?
     Were both birds killed by a goshawk, when they fed on them there?
     (I have found boreals killed by goshawks in the past)



For help referencing place names, use the Yellowstone SpotR app:
    • Download Yellowstone SpotR for Apple iOS
    • Download Yellowstone SpotR for Google Android


View slide show