Nest-site Selection by Pennsylvania Broadwings

On October 19th, Rebecca presented at the 50th Anniversary Raptor Research Foundation Conference in Cape May, New Jersey on the results from our study looking at the habitat or land cover surrounding Broad-winged Hawk nests in Pennsylvania. 

HMS former trainees and staff at the 2016 RRF Conference in Cape May, NJ

This work expanded on our original project findings based on 19 nests for 2014-2015, used in Rebecca's Master's thesis, to include nest sites from 2016 and those identified in the 2nd Pennsylvania Breeding Bird Atlas (Wilson et al. 2012). The purpose it to try to figure out if Broadwings are selecting certain habitat features or types of forest for their nests.

Yellow blocks= areas where BWHA nests were found in the 80's but were not found again in 00's

Dark red and dark blue dots= BWHA nest sites AND lighter red and blue dots are the available sites where BWHAs were not confirmed (also known as "random sites")

Average land cover composition of 60 BWHA nests in Pennsylvania. Over 79% average total forest cover surrounding 1km of BWHA nests

We wanted to compare confirmed nest sites with available "random" sites. Available sites were randomly selected at a range of distances from 2km to 10km and 10km to 20km from nest sites

Nest and Available sites selected in areas where there was less than 60% deciduous forest cover surrounding 1km of sites

Nest and Available sites selected in areas where there was greater than 60% deciduous forest cover surrounding 1km of sites

Habitat use composition of 9 female Broadwings on their breeding grounds, during the months of June-August

Map (left) with 85 roost sites of 9 tagged Broadwings plotted in ArcGIS 

Nest Searching with Zach Bordner

   Each Spring, the Broad-Winged Hawk Project has begun the same way: scrambling to locate nests to ensure we have sufficient birds to study. The prime window of opportunity is short and the hawks unpredictable. Though inconspicuous for most of their breeding cycle, Broadwings ease into the reclusive portion of their lives gradually, their return to northern territories punctuated by shrill whistles. Bordering on boisterous, courting pairs can be very loud, frequently exchanging vocalizations from both perch and sky. Because courtship rituals continue for several weeks, it is relatively easy, during this time to identify an established territory. Pinpointing the location of a nest however, almost always presents a bigger challenge. Noisy as they may be, flight affords them the ability to cover much ground quickly and quietly making them difficult to trace as they navigate their grounds. 

   

   The most reliable way to locate a nest is to follow an individual with building material back to a home tree, the catch being that birds will not so easily give up such a secret in the presence of a perceived threat. I believe the saying goes, a watched Broadwing never boils... Usually if you meet, they will be spooked enough to either take their find elsewhere or drop it altogether before retreating. It is possible to circumvent this trepidation by sitting tight in a well concealed location and hope that a bird comes within your field of view. Whether they can be tracked or not, a bird carrying materials is a great sign that a structure is nearby. Comparably suggestive, though only sometimes exhibited, are the more confrontational responses to an intrusion into a nesting space. This can range from agitated vocalizations from a number of alternating perches and defensive circling overhead to  repeated warning dives. Aggressive swooping is atypical, but when they do resort to this, looking skyward will likely yield a nest.

    Spotting something so telling this early on is uncommon, so the best course of action is to first amass a bank of observations and plot them on a map to isolate an area of high activity and manageable size. If prior year's sites are known, it is the best place to start. Instances of pair interactions can be weighed on heavily, since it can loosely be said that most pair bonding occurs near to the nest site. Thanks to powered flight, our near is slightly askew from theirs, so this can still comprise an area of a few hundred meters square. Nests can be rather nondescript so all reasonable stick heavy structures should be noted and monitored to check for new material and promising examples can be staked out from a distance to identify the owner. They can vary dramatically in size and orientation but fresh greenery at nests edge is a solid cue to follow, as live sprigs are added regularly throughout the season. 

  

   By the time females lay their clutch and begin incubating, a veil of foliage is falling on the forest uppers further obscuring the treetops. Broadwings retreat below canopy and all but cease vocalizations except for the brief exchanges preceding prey deliveries from male to female. These transfers usually occur at a few locations closely surrounding the nest, and after hatching at the nest itself, increasing in frequency as the young grow older. Now, these occurrences may be the only indicators of nest presence apart from a direct view of a female on site, who despite a near constant presence, may be invisible when hunkered down low. A month later, nestlings will have emerged, and soon whitewash around the base of the tree will become an additional sign of occupancy.

   Looking back, the very first nest that I found on the job represented a bit of an anomaly and proved to be a very misleading introduction into the world of nest searching. On my second visit to a study site I was greeted, at my parking space no less, by both halves of a pair, each with sticks grasped in their beaks. After conveniently shuttling them to their final destination in a nearby oak, they were off to fetch more, this time comically large just in case I missed it the first time. That was a freebie for me never repeated. The vast majority of cases involve patiently gathering pieces of a puzzle until you have a complete picture. Often whether or not you are in the right place at the right time to see the important parts is squarely in the hands of luck. Our quarry is unpredictable and the birds can appear to be everywhere at once or nowhere at all. I have passed, oblivious, beneath more nests than I care to admit, and have been fooled more than a few times by the work of squirrels, crows, and cooper's hawks alike. Despite the challenges, and perhaps because of them, I think I can speak for everyone involved when I say that finding an active nest is an incredibly satisfying experience because it translates into so much more. Each confirmed nest opens the doors to a wealth of knowledge and the potential answers to many questions formerly so far out of reach. It represents a rare look into nesting behavior and habitat, as well as a chance to remotely monitor movements across continents, into the southern expanse. 

   

   Early this week, Rosalie, our tagged female on the Sanctuary showed up at the cabin property where I live currently. It just so happens that she and I share a territory and I have seen her and her mate meander through here regularly since their April return. A bit maddening during the weeks it took to locate their nest, but now a pleasant reminder of what that effort became. A bird with an antenna is a very curious thing. Her backpack tracker looked secure, everything exactly where it should be. I watched her lazily from the hammock feeling glad that there would be no need to chase her today, excited by what this marriage of technology and nature will tell us, content to have the satellites take on the legwork for a little while. 

Zach holding Rosalie, female from the River of Rocks nest on Hawk Mountain Sanctuary

 

Blog post and photos by Broadwing Project Field Assistant Zach Bordner- July 2016

A Trip to the Allegheny National Forest

May 23 to May 26, 2016

    Zach, Randy and I set out on our road trip to the Allegheny National Forest (ANF) early Monday morning. The forecast for the next couple of days was looking good, and the potential of confirming Broadwing nests in the ANF was promising. Upon arrival we were greeted by our hosts Don Watts and Scott Stoleson. Dr. Scott Stoleson is the Research Wildlife Biologist at the USFS Northern Research Station lab and a Research Associate of the Roger Tory Peterson Institute. Don Watts is a biological technical assistant for the USFS, monitors Kestrel nestboxes and assists with breeding bird surveys, nest finding and the Christmas Bird Count in the ANF. Both are Master Banders and are very knowledgeable about bird calls, identification and nesting!

   In 2015 Scott, Don and others were able to gather nesting data for us at 5 sites. This year they were on the lookout again, and prior to our trip already confirmed 1 nest- including other areas where birds were seen and thought to be nesting.

   At 5:45am on Tuesday morning we awoke to the sounds of forest birds, turned on the coffee maker and got dressed for a day of nest searching. Don and Scott arrived an hour later and we jumped in our cars to head off to the one confirmed nest site in the southwest portion of the forest. Don pointed out last years nest tree, a Black Cherry, where at least one young fledged and just 50 yards away in a Red Oak was a Broadwing incubating. We took down the GPS location, jotted down a few notes in the field notebook and made our way to the next site. The second location had Broadwings in the past, but in recent years they have been unable to pinpoint any new nests.

   We all spread out to search the area. Don and Scott went to scope out two very large nests that were 2+ years old, in Black Cherry trees. I immediately ruled the nests out due to their size, it looked to me like they were more Red-tail like than anything. Boy, was I wrong. After using the scope to zoom in on the nest, we confirmed a female Broadwing incubating! I was very surprised to see this and realized I was too quick to judge the size of that nest.

   We continued to drive to other known Broadwing territories and by the end of the day had a total of 3 nests confirmed. We got back to our cabin around 7pm, made dinner, recapped our day and were in bed by 10. 

   The next morning, Don treated us to a traditional breakfast at a local restaurant in Warren. We then made our way to the ranger station in the northeast to meet with Dani, a wildlife tech for the USFS, who has been helping Don and Scott track the Broadwings in the ANF. Our first stop was a nest that fledged young last year. On our way to that spot Don showed us a nest that was not active last year but once belonged to a raptor. We approached the dead Beech tree to find loads of white down scattered on the stick nest. It was active! We put the scope on it, and not too long after... the call of a Broadwing. Hooray! Nest number 4.

   We continued searching at other locations and when it was time to head back to the cabin, we were driving on a forest service road and Randy shouted out to stop the truck. Dani pulled over and we all grabbed our binoculars and what do you know, there was a Broadwing sitting on the nest, with its head barely visible! Zach went to GPS the nest in an Ash tree, and we all got back in the truck feeling relieved that we were now up to 5 nests. 

   The forecast was calling for rain Thursday afternoon so we decided to spend the morning searching before we headed back home. Scott and Don arrived at the cabin at 7 am and we were in the woods by 7:30. We stopped at a few more sites and were able to confirm our 6th and final nest before noon. We celebrated at a local pub with burgers and sweet potato fries!

   The trip to the ANF was very exciting and rewarding. We came out with 6 confirmed Broadwing nests and a few more territories that the ANF crew will continue to monitor. We had spectacular hosts, Don, Scott, and Dani. We thank you for spending time with us in the field, providing us with a place to stay, treating us to meals, showing us other raptor nests, and taking us on a tour of the old growth at Heart's Content. We can't wait to return in a few weeks in hopes of putting two transmitters on your birds up there! :)

Early mornings in the forest

Painted trillium was popping up all over

Randy atop the massive rock outcrop in the middle of the woods

a little posing with the rocks :)

Allegheny Reservoir

Randy and what was Pennsylvania's tallest White Pine before it fell in the fall of 2015

Broadwing peeking out at us

Rebecca examining a potential nest

making our way through the forest

Randy scoping an active nest to see if the female is on it

Don showing us where last years nest was

Thank you to the ANF team and for an exciting trip exploring yet another beautiful forest of Pennsylvania!

The Birds are Back in Town

Hawk Mountain field research staff and volunteers have been busy since mid April searching for nest sites and seeing which birds have returned. Two of last years tagged birds, Ridgena and Pocono Penny, have returned and are currently nesting! You may remember from past blog posts that we were not sure what happened to Ridgena since her last location from Colombia was on January 26th. 
Laurie went out to the old nest site at the end of April and confirmed that Ridgena returned after getting a good look at the USGS band on her leg. No antenna or backpack was seen at that time. We will attempt to re trap her to determine if the unit is still on, and if so, remove it so it can be refurbished and hopefully put on another bird at a later date.

We will continue to have people in the field to identify if banded individuals have returned to sites like Morgantown, French Creek State Park, Delaware State Forest and Hawk Mountain.

* * *

 Chenango's interesting movements during her first year migrating. On fall migration Chenango spent time in the southwest portion of Mexico for about 2 months before heading to El Salvador. She stayed in El Salvador from 1/18 to 4/15. As she moved north, she hugged the Gulf Coast, went up through Texas and followed the Mississippi Flyway until she decided to move south again, down into Georgia, where she currently is located.

Chenango's fall `15 and spring `16 migration

    Sadie arrived in PA around May 3rd and was back on her breeding grounds in the Delaware State Forest on May 9th. We are currently working on locating her new nest site as well as getting a visual confirmation of her with backpack and bands.

Sadie fall `15 and spring `16 migration

Pocono Penny was back in PA after April 24th and at Stony Acres on April 27th. It was confirmed just 12 days later that she was reusing last years nest (see images below).  

Pocono Penny fall `15 and spring `16 migration

A look at all of the 2015 birds tagged in Pennsylvania on both southbound (downward pointing arrows) and northbound (upward pointing arrows) migrations, as well as wintering locations (circle points).

Movements from all 2015 tagged Broadwings

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   This is the first time in our 2 year study that we have birds reusing nests from previous years.Three nests are being reused in 2016, two nests from 2014 (one on HMS property and another in New Ringgold) and one from 2015 in the Delaware State Forest.

May 9th, 2016:  Penny settled down in the 2015 nest (PhotoCred. R.Farley)

Pocono Penny with visible antenna from transmitter

Adult Broadwing from pair on Hawk Mountain Sanctuary

  

 As of now we have a total of 9 confirmed nest sites throughout the three regions. We are hoping to confirm an additional 3-5 nests by the end of May. 

   Next week Rebecca, Zach and Randy will be headed on a little road trip to the Allegheny National Forest to search for Broadwing nests with the help from the staff at ANF. The goal is to find 3-5 nests and to come back after the young have hatched to put units on two adults. 

Be sure to check in on Chenango's movements at Broadwing Tracking Maps
Also do not forget to Like us on Facebook at The Broad-winged Hawk Project

Spring is Here

   March 20th marked the official start of spring, creating anticipation among the project staff as we await the arrival of Broadwings back to Pennsylvania. Last year our returning tagged Broadwing, Abbo, made her way into PA on May 4th. 
   Two of our birds, Pocono Penny and Sadie, have already started their spring migration. Pocono Penny wintered in western Brazil, close to the border of Peru. Sadie, wintered in southeast Peru, and was the 2015 bird to travel the furthest south. We recently received a location for Chenango last week but she is still in El Salvador and has not made any northward movements. We are hoping that Ridgena's unit comes back on and that she will return this spring. Her last known location was east of the Magdalena River in Colombia on January 26th. Since our last post, we still have not heard from Rachel Carson. Her last location was back in early December, from her wintering location near El Naranjo, Nicaragua. We still believe that she died due to the signals received from her transmitter. 

Movements of 2015 tagged Broadwings as of 14 March 2016

   Once the birds have returned to their breeding grounds we will send out our staff and volunteers to confirm tagged and color banded individuals have returned. We will also do our best to locate the new nest tree for any territory where we worked in 2015. In addition to this work, we will be trapping four more adults in 2016. Our goal is to tag two individuals on or near Hawk Mountain Sanctuary as well as two in the Allegheny National Forest of northwest Pennsylvania. The ANF staff located 5 Broadwing nests last year, providing a head start at locating nests and territories for this year.  

Be sure to check in on our northbound migrants at Broadwing Tracking Maps
Also do not forget to Like us on Facebook at The Broad-winged Hawk Project

Where are they Wintering?

Happy New Year!

Wow, the end of 2015 really flew by! We hope everyone had a wonderful holiday spent with family and friends.

   We are happy to report that we are still receiving locations for four of the five birds tagged in 2015. 

Chenango, the juvenile tagged on migration is wintering in Mexico. Until recently, she was wintering west of Mexico City. Just last week she moved south along the coast in Oaxaca and has now made it to Tabasco. Ridgena, from Hawk Mountain, is wintering in Colombia in the Cordillera Oriental Mountain Range! Known as the East Andes, the Cordillera Oriental is part of the three branches of the Colombian Andes. She has been there since the middle of October and it seems like the perfect place for a Broadwing to winter!

   Pocono Penny (Delaware State Forest-Stoney Acres site) is in the Amazon in Brazil, not too far from the border of Colombia, Peru and Brazil. Once reaching South America, Pocono Penny's movements are the most similar to Abbo's. Currently, Pocono Penny is staying within one small area compared to Abbo who continued to move while on her wintering grounds throughout Brazil.
   Sadie, the third female tagged in the Delaware State Forest has moved the furthest south. Instead of moving into Brazil from Colombia she stayed west and continued moving down through Peru. Near the end of November she flew into the Tambopata National Reserve which is in the Peruvian Amazon Basin and her current location as of 9 January 2016.

   Unfortunately, we believe Rachel Carson from the Delaware State Forest (Mud Pond site) did not survive due to the location points prior to the last time her unit was on and signaled. She did make it all the way to Nicaragua and was wintering it what looks to be a agricultural area with fragmented forest. 

Movements as of 8 January 2015

Keep up with the birds @

http://www.hawkmountain.org/birdtracker/

   In other Broadwing Project news, Rebecca had a great trip out west at the Raptor Research Conference in November to present preliminary results on Broadwing migration. She met a lot of great people and met up with several former Hawk Mt trainees, saw some fantastic talks and enjoyed all things raptors for 5 days!

Former HMS Conservation Science Trainees at the 2015 RRF Conference. Top Left: Katie Harrington, Rebecca McCabe, Anna Autilio. Bottom Left: Hankyu Kim and Jean-Francois Therrien (Hawk Mountain Biologist)

   We recently finished watching the nest camera videos, and all of the data has been entered. We found many similarities between both years as well as some differences. We will be sure to post a few videos from the nesting pair in Shartlesville in the next blog for everyone to see. In addition to videos we have begun to assess habitat around nest and roost sites.

   The next few months will be filled with analyses as we being to dive into the data from the last two years. We will continue to update you on the birds and the work we are doing!