WPBO Owls Fall 2010: August 2008

Thursday, August 21, 2008

Nothing but mammals last night. We came across a fox early in the night. A little investigation revealed that it had been feeding on a Ring-billed Gull. A doe and its fawn gave us a good scare in the middle of the night. The only thing in the nets all night was a rather angry bat. Given the recent lack of productivity, and the weather forecast for the next few nights, we will begin making the switch over to a day schedule. That being said, we will still be opening the nets and giving it a few hours for a few more nights.

Wednesday, August 20, 2008

Things have really slowed down again over the last two nights. Monday night we banded just 1 juvenile Saw-whet, and last night we banded 2. We're hoping things pick up again, but at this point we're not holding our breath. At least we were treated to a beautiful sunrise this morning. The waterbird count has begun, and waterbird counter Tim Baerwald has started the waterbird blog. Once we're done with the owls we'll get the sightings blog going again.

Monday, August 18, 2008

The last week has been fairly productive. On Tuesday we finally broke 100 owls for the season. Friday night we banded 13 juvenile and 1 adult Saw-whet, making it the most productive night to date. Saturday night the first Long-eared Owl of the season was banded (photo above). The Long-eared still had a few of the downy feathers it wore as a chick. It was also very lightly colored, as you can see well in the underwing, which means it was very likely a male. It's amazing to catch these juvenile owls knowing that just a few months ago they were eggs. The photo below shows a juvenile Saw-whet and the Long-eared.

We have been told be multiple visitors that they have received incorrect information when they have called to inquire about the owl banding. With the exception of 6 nights, when it was either raining or too windy, we have banded every night since July 1st. We plan to continue until at least August 25th. The first net check is being run around 10:30 PM. If you come to visit, come to the door in the back of the Owl's Roost gift shop. If we are not there it means that we are back at the nets. Please wait at the gift shop for our return, and DO NOT come back into the net lanes. We bring all of the owls we catch back to the Owl's Roost for banding where you will have the opportunity to see them up close. Because I am the fall's field ornithologist, if the owls stop moving we will stop owl banding, switch over to a day schedule, and begin conducting the songbird census. We will give a few days notice on this blog when we are about to make the switch.
We had a big turnout for the summer's last Thursday night owl presentation. Thanks to all of you who attended over the summer. Your enthusiasm and encouragement were greatly appreciated. Nova will be leaving next month, but Keith and Wendy will be returning to do the fall owl banding, and I will be doing owl presentations this fall. If you are interested in attending, please check here for the schedule early next month.

Wednesday, August 6, 2008

We've begun getting a steady trickle of juvenile Saw-whets, 19 have been banded over the last seven days. The above photo shows an adult on the left, and a juvenile on the right. As they did last summer, the adult captures dropped off soon after we began seeing active flight feather molt. An adult caught last night was in active molt, replacing the flight feathers on its wings and growing in a new tail (photo below).

The juveniles are also in active molt. They are molting out of the juvenile plumage that they wear for a very short time of their lives. You can see the first few adult breast feathers coming in on the left side of the photo below.

We catch a few bats during the summer. Considering how many are around right now we're glad that we're not catching more. The Red Bat pictured below was caught a few nights ago. They are a beautiful bat. It was pointed out to me that I had incorrectly labeled this as a Hoary Bat.

Friday, August 1, 2008

While the folks who attended our Thursday evening program tonight got treated to a juvenile Saw-whet early in the night, a fog soon rolled in and effectively shut us down. Maybe tomorrow night.......hope springs eternal.

Our New Summer Owl Study

During the summer of 2006 WPBO conducted an exploratory owl banding research project at the Point. Our project ran 3 weeks, and our efforts resulted in the capture of 208 owls; 206 Northern Saw-whet Owls (NSWO) and 2 Long-eared Owls. Of the 206 NSWO captured, 200 were juvenile birds. While the spring and fall migrations of NSWO have become increasingly well studied across the continent, these results represent the first documentation of a significant concentration of juvenile NSWO during the post-breeding period.

Thanks in large part to generous donations made by two individuals and pledges to the spring staff birdathon, we have been able to continue and expand this study during the summer of 2007. We began on July 1st, and as of August 10th we have banded 542 owls; 539 NSWO and 3 Long-eared Owls. As in 2006, the majority of the NSWO we have banded this summer have been juveniles.

In addition to the regular data we collect on all owls, we are visually accessing fat stores and muscle mass on all of the juveniles. Among North American owls only NSWO and Boreal Owls have a juvenile plumage that is significantly different from adult plumage. The juveniles begin actively molting out of their juvenile plumage and into adult plumage during our study period. Detailed descriptions of the molt progression on each juvenile have been collected.

Owl banding Spring 2007

Several changes were made to the spring owl banding protocol in 2007. These changes were made in an effort to increase our captures, thereby increasing our data base and our knowledge of the owl migration at Whitefish Point. Owl banding data collected by WPBO during previous springs clearly demonstrated that the Saw-whet migration at Whitefish Point was already at its peak during the 1st week of April. Therefore, the start date of the spring owl research was moved up from the previous start date of April 1st to March 15th. Audiolure was also introduced to the spring owl research for the first time. Audiolure is simply the practice of broadcasting a recording of an owl's call to lure them into the research area. This is a technique implemented at every other owl migration banding site that we know of, and has been used during the fall season at Whitefish Point since the fall study began in 1993. It has been documented that this practice increases Saw-whet captures 5-10 fold.
This spring the calls of Northern Saw-whet and Boreal Owls were broadcast. As the data from previous seasons suggested would be the case, Boreals were at the bottom of their irruptive cycle and none were captured. We fully expect that Boreal Owl captures during the next irruption will increase significantly due to the use of audiolure. As for Saw-whets, the changes proved a huge success after just one season. We banded nearly 280 Saw-whets during March alone; the previous high for an entire spring season was 122. Our total captures for all owl species in March was 318, these results are also higher than the total captures of any previous spring season. The chart below demonstrates the effectiveness of the changes implemented in the spring of 2007.

General Information

Whitefish Point Bird Observatory (WPBO) conducts long-term owl migration studies in both spring and fall. WPBO began its oversight of the spring owl research at Whitefish Point (WP) in 1988, and began the fall study in 1993. A summer study was developed during the summer of 2006 when a dispersal of juvenile Northern Saw-whet Owls was discovered within the study area. These WPBO research projects have resulted in the banding of over 7,000 owls of eight species; Great Horned, Northern Hawk, Barred, Great Gray, Long-eared, Short-eared, Boreal, and Northern Saw-whet. This reasearch has established WP as one of the most diverse owl migration sites on the continent.

* Study periods:
Spring: March 15-May 31
Summer: currently July 1-August 31
Fall: September 15- October 31

**During the study periods nets are opened nightly, weather permitting , 1/2 hour after sunset and closed 1/2 hour before sunrise. Nets are not opened during periods of rain or high winds.

FAQs

Why do we band owls?
The owl banding project is the most effective way we have to monitor the number of owls migrating through Whitefish Point. For example, without the owl banding project just 3 Saw-whet Owls would have be documented in the spring of 2007. Through the owl banding project, 750 Saw-whets were banded and 32 that were already banded were caught. Without specific efforts to document the owl migration at Whitefish Point it would go virtually undetected. For more information on bird banding visit the Bird Banding Lab's website, which can be linked out of the WPBO website.

How do we catch and handle the owls?
All of the owls in our studies are captured in mist nets that are made specifically for bird banding. The mist nets we use are 12 meters long andabout 10 feet high. Due to the size difference between species that we catch two different mesh sizes are used. The nets are placed in openings among the trees at Whitefish Point. To help attract the owls into the netlanes audiolure is used. Audiolure is simply the broadcast of an owls call.In spring and fall both Saw-whet and Boreal Owl calls are broadcast, only saw-whet calls are broadcast in the summer. We do not wear gloves while getting extracting owls from the nets or during the banding and measuring proccess. Like many other things, these procedures are more difficult when wearing gloves. Extractions in particular are already difficult and would be virtually impossible while wearing heavy gloves. Yes, we do occasionally get bit or have the birds get us with their talons, and yes it does hurt. To band and weigh the owls they are placed in cans. This is the common practice when banding birds of prey and actually serves to calm the birds down.

What data do we collect?
Each owl is fitted with an individually numbered U.S. Geological Survey band. These bands are issued to federally licensed bird banders by the Bird Banding Lab in Maryland. The main measurments we collect are weight, tail and wing chord length. If the bird has flight feather molt, the molt pattern is recorded. These measurements and the molt patterns help us determine the age and sex of many of the owls that are captured. The data, including the band number is then submitted to the Bird Banding Lab for inclusion in their database.