Tracking MPG Ranch pygmy-owls: field journal transcript
Our banding efforts resumed this February with our Northern Pygmy-owl project (also documented in the 02/13/15 Field Note).
2/3/15: Eric Rasmussen and I catch the long sought-after male pygmy-owl that defends a territory around West Baldy Ridge. We attach a small VHF transmitter to its back (#960) before letting it go. The owl flies to a nearby perch and we confirm that the transmitter antenna is placed correctly (red arrow below points to the antenna).
2/3/15 – 2/24/15: I monitor #960 every three days and keep finding him in the same area. Our hope that this owl will breed here grows every day. Within a few days it becomes evident that this owl occupies a general territory near West Baldy Ridge.
Legend:RED-MPG Ranch boundary; Yellow-General territory. On 03/04/15: location where owl #960 is found with a mate.
3/4/15: After hiking for a couple hours from Sheep Camp and up to the top of West Baldy ridge, I find #960 (red arrow in the photo below) at 8:00am with what I believe to be his mate! The male vocalizes more and has a deeper hoot in contrast to the softer and higher-pitched female.
Snow still blankets the upper portion of West Baldy Ridge. This picture shows the scenery at the site when looking out to the northwest.
3/6/15: I do not visually confirm the owl. We triangulate #960’s position to an area in its typical home range, on the north-facing slope of West Baldy.
3/9/15: Today #960 is back at the road junction and is eating a beheaded vole. The pygmy-owl moves very little during 5 hours of observation, and then it decides to nap and soak in the afternoon sun with the vole still in its talons. I find no female around.
3/10/15: We decide to step up the challenge to tracking #960 over several hours between dusk and dawn. At 7:30pm, I record a burst of activity: the male kills a vole, starts pecking at it, but then takes off and flies up the draw. Honing on the transmitter signals, I finally catch up to it before 8:00pm despite the failing light. #960 choses to roost in mistletoe-infested Douglas-firs for the night. It hoots a couple of times until 8:05pm before it falls silent and lets Long-eared Owls and Great-horned Owls take over the hooting symphony.
3/11/15: Early in the morning we find the owl at the same roost. At 7:30 am, #960 moves approximately 40 meters and gives a few hoots. He then flies straight up the draw to meet with his mate. I hear them interact for over 20 minutes with mixed vocalizations. As soon as I reach the pair, the male shoots back down to the road junction, where we have found it hunting voles for the last two days.
The male leaves the female at 8:20am. The female stays near a suspected nesting site for 10 minutes before disappearing into the forest. The Ponderosa Pine snag visible in this picture contains numerous cavities suitable for a pygmy-owl nest.
3/11/15: Tracking the male #960 over several hours enables us to better understand a pygmy-owl’s behavior and movement. Here is a map of the owl’s movement and suspected nesting site on 3/11/15 with a reference to where we initially captured it. The distance between its potential nesting site and where I find it at 9:15am, where it hunts voles, is approximately 750 meters apart (1/2 mile).
Summary: Our tracking efforts give us a glimpse into the size of its home range. #960 has been located over a range surpassing 165 acres thus far.
William obtained an MS in Wildlife Biology from the University of Montana in 2018 focused on the influence of habitat selection on reproductive outcomes of Lewis’s Woodpecker in the Bitterroot Valley, MT.
William coordinates the “Intermountain West Collaborative” Motus project. Motus is an international collaborative network that permits tracking migration of small wildlife by using telemetry and automated receiving units. In addition to Motus, William also leads various banding operations at MPG Ranch, including the capture and tracking of Lewis’s Woodpecker, Northern Pygmy-owl, Flammulated Owl, Common Poorwill, and Common Nighthawk.
Outside of work William enjoys everything outdoors, team sports, and traveling.