Nicole and Bryce recently teamed up with a good friend of the project, Sylvain Bourdages, in Grande Prairie, Alberta for a week of exciting field work. An isolated patch of agricultural land surrounded by dense boreal forest, this area is a famous stopover for an incredible diversity and abundance of Red-tailed Hawks. At least, it is in a normal year! Sylvain has lived in the region two decades now, and has noticed that birds not only arrived later than usual, but were also relatively scarce overall this spring.
But in spite of the unusually quiet backroads, the week was a great success with twelve new transmitters deployed on an excellent suite of fascinating phenotypes. Now we eagerly wait to see where these birds will go to breed this summer!
We are fortunate that three of our birds have settled in summer locations that are in range of a cellular tower, so we are receiving regular updates on their movements. Two of these individuals took an exciting spring migratory route that we haven’t seen until now. Sefi and Ja’Marr moved along the coast of British Columbia and southeast Alaska, hopping from island to island and passing over cities such as Juneau. Eventually, both birds ended up in south central Alaska. Comparing these two individuals against Ragnar, who ended up at a breeding site in central British Columbia, creates an opportunity to look at the similarities and differences in their plumage, age, and purported sex to provide some interesting context to the movement patterns we are seeing.
These individuals are similar in many aspects of their plumage. They are all dark morphs, with fully red tails. Ja’Marr and Sefi each have harlani like streaking in the breast, while Ragnar is a very deep dark and solid brown throughout the body. The other striking difference is in the tail pattern, where Ragnar has rather thick and regular tail banding while the other two birds have irregular barring that is mostly restricted to the base of the tail, and includes harlani-like spotting. Although Ja’Marr is not breeding (as indicated by it’s more irregular and widespread movement patterns), it is interesting to compare the plumage similarities between Ja’Marr and Sefi, and the proximity to their summer locations, to Ragnar’s breeding location. These individuals are an important contribution to understanding whether or not birds like Sefi and Ja’Marr that occur well within the distribution of harlani represent the phenotypic diversity of that population, or represent plumage traits that come from calurus to the south, and occur because of contact and interbreeding.
The image above illustrates the home range pattern in a heat map for each individual for the month of June. The red clusters indicate areas of high use. Sefi seems to have nested in a site across the bay from Valdez, however there is some spread to the points. Contrasted against Ragnar, who also seems to have bred, the difference is striking. Ragnar has a very centralized, almost circular cluster pattern suggesting that the bird is tied tightly to a nest location. The difference between these two nesting patterns could be explained by sex. Based on morphometrics at the time of capture, Ragnar was tentatively sexed as a male while Sefi was tentatively sexed as a female. At face value, the patterns in their movements don’t make much sense considering their likely sex, since the female is more tied to the nest during the first part of the nesting period, while the male is more random in his movements as he works to provision the incubating female, and later, the young brood.
Ja’Marr’s movements are widespread, with multiple areas of high use. The lack of a centralized home range pattern suggests that Ja’Marr did not breed this summer. This makes sense, since the bird was a second-cycle at the time of capture this past winter. Generally, Red-tailed Hawk do not breed until the end of their third or fourth-cycle. Ja’Marr represents what is termed as a ‘floater’, or an individual that has not yet joined the breeding population. These floaters drift around until they find an opportunity to breed. If all goes well, we may capture when this occurs for this individual. Taken together with other birds we tagged as second-cycles, we can provide some very interesting insight into patterns of movement during the floater period, as well as the timing of recruitment into the breeding population.
Although at the moment we can only mostly speculate about the patterns we are seeing, we are situated to confirm most of our suspicions. For instance, we can confirm the sex of each individual using molecular techniques, and take a more systematic approach to analyzing the data to investigate what factors (such as sex, age, etc) best explain the movement patterns we see. There is a lot of exciting things to dig into, so stay tuned for more.
Last month, Bryce caught this stunning dark bird just north of Lawrence, Kansas and discovered that it was already banded. After reporting the band and asking around, he learned that the individual had been captured and banded near Grand Prairie, Alberta in May 2015 by Sylvain Bourdages, an active raptor bander and friend of the project. Even more, Sylvain happened to take photos of the bird that he willingly shared. This provides an excellent comparison between juvenile and adult plumage, as well as a known age for this bird. When it was banded in May 2015, it was still in its first cycle (Juvenal) plumage, despite that it had started its second prebasic molt. Thus, this bird can now be aged as an eighth cycle. From the molt limits in the primaries in the photos above, we can estimate its age as after fourth-cycle, a pattern that is not often seen and generally is assumed to suggest a rather advanced age bird. It is then a valued insight to see this pattern on a bird that we know is in its eighth cycle.
This bird that we now call Ben is outfitted with a GSM transmitter, and we will provide updates when we have a nesting location, and eventually its full cycle migratory path. Another benefit of this recapture event is to contrast the information we gain from the banding effort against the information we gain from the transmitter effort.
Thanks to Sylvain Bourdages for all of his efforts to capture and band migrants in his region of Canada, and for the wisdom to photograph every bird he gets in hand. Because of his efforts and those of folks like him, this will likely be the first of many of these types of recoveries for our research program.
Luke and Bryce recently captured this amazing juvenile Rough-legged x Red-tailed Hawk hybrid in eastern Kansas.
Here is our breakdown of the identification – Note the multiple Rough-legged Hawk traits such as head coloration and pattern, including pale auriculars; subtle carpal patch; buffy base coloration to breast and underwing; pale and unpatterned base to flight feathers on wing, especially in the primaries; seemingly unpatterned greater upperwing coverts (expected to be more patterned in RTHA, especially harlani); fairly solid and noticeable bellyband that sits lower than expected for RTHA; long wing and tail measurements; relatively small feet for RTHA; and tarsi feathering more extensive than RTHA. Otherwise, the bird looks mostly like a juvenile harlani in plumage, especially the tail pattern.
Our hope is that over the next few years, we are able to capture other individuals like this to better understand the regularity of hybridization events in the Red-tailed Hawk. For now, eBird and the Macualay Library are serving as great resources for strengthening our understanding of how often this hybrid pair occurs. You can explore images of hybrid Red-tailed X Rough-legged Hawks in the Macaulay Library here.
One of the research goals of the Red-tailed Hawk Project is to better understand the “Krider’s” Red-tailed Hawk (Buteo jamaicensis kriderii). There has long been debate about the validity of this currently recognized subspecies, because of its variability and that it breeds alongside (and with) birds we consider as the subspecies borealis. The two most popular competing thoughts are that 1) borealis expanded its distribution westward into the northern Great Plains along with the westward expansion of European settlement (consider homesteading and the resulting increase in trees) and is currently in a slow process of subsuming kriderii, or 2) kriderii represents a pale morph of borealis that is found in the northern Great Plains. The two may actually not be mutually exclusive, but for now our approach is to focus on collecting data so we can gain some insight that might inform a better perspective on the situation.
Bryce recently tagged 5 individuals in southern Louisiana, and 1 individual in western Missouri that all possess kriderii traits to some degree. The hope is that each will soon return to their breeding territories. Unlike the more northerly breeding phenotypes we have tagged, we should obtain breeding locations as the birds begin their reproductive effort this spring. Once we do, Bryce plans to travel to each territory and record the mate for each of these birds, and photograph the phenotypes of the offspring that come from each pair. Our hope is that this will compliment genomic analyses to describe the relatedness of individuals that posses kriderii traits, and those that are borealis in plumage.
Many thanks to the individuals in Louisiana that helped Bryce – Matt Mullenix, Garrett Rhyne, Dylan Bakner, and Patty Rodriguez.
Over the weekend, Neil Paprocki caught and outfitted this light morph harlani with a GPS/GSM transmitter in Northern Idaho.
The members of our group decided that this harlani, the first bird to be tagged for the winter 2021/2022 field season, is to be named “Liggy” in honor of our mentor and friend Jerry Liguori. “Liggy” will be our flagship bird as we work to understand the unique plumage characteristics of harlani, and how this outstanding subspecies relates to the rest of the Red-tailed Hawk populations across North America.
In October, Bryce had the privilege of visiting the Cedar Grove Ornithological Research Station (CGORS), a long-term fall migration monitoring station along the shore of Lake Michigan in central Wisconsin. Each year, strong winds from the west cause a large number of migrants to build up along the shore as they move south. CGORS is uniquely situated to take advantage of this build up, and capture and band migrants. Although this has been a long-term site, the banding effort has provided only glimpses into where the individuals passing through this region come from, and where they go. Because of this, CGORS was interested in collaborating with the Red-tailed Hawk Project to add to our efforts to understand movement in the Great Lakes region, and gain some insight into the birds they interact with each fall.
In the end, Sue Kaehler and Danny Erickson put out four transmitters on some stunning individuals. To see these four individuals in more detail, visit the Movement Ecology page.
One individual, Otto, is fairly typical in appearance for the borealis that breed in Wisconsin. The bird currently seems to maintain a winter territory only kilometers west of the research station near Sheboygan, Wisconsin. It is likely that this bird will maintain this territory all winter, and may breed at the same location, and so opens up the opportunity for comparative work between winter territories of resident birds relative to migrants.
For instance, after being tagged, Madison moved down to Kentucky where it seems to have found a winter territory. Comparing the differences in winter territory between individuals and populations, as well as the characteristics of these locations, will give us insight into potential factors that drive differential behaviors in seasonal movements, as well as what factors contribute to a high quality wintering site. Another notable difference between these two birds is their age – Madison is a second-cycle and so may provide insight into how movements and territories may change across the annual cycle as birds age and become more experienced.
As our scope continues to grow, tagging second-cycle individuals and residents will become more important to better understand the factors involved in governing the different movement strategies between individuals and populations. We really appreciate CGORS for joining our effort and enabling us to better understand the intricacies in the life of the Red-tailed Hawk.
Special thanks to everyone at CGORS that assisted with getting these transmitters out, especially Jenn Schneiderman for her excellent holds.
As we approach mid-November there is a lot to report on as our Michigan Red-tailed Hawks head towards their wintering grounds. So far, we have gotten data from 9 of the 11, hopefully we hear from the others. Here is a quick update on 7 of our birds we have heard from. First up are the new birds that have checked in over the last few weeks.
A gorgeous Northern bird that recently dumped a ton of data including his breeding location. This is our only tagged MI bird that bred in Northern Quebec. He was approximately 115km northwest of a town called Matagami. We are still waiting on a backlog of data to come in so we do not know where he is currently but he is definitely on the move.
We hadn’t heard from this bird since initially deploying the transmitter on April 2nd. The reason being is that on the same day we tagged her she crossed the Straits and reached her breeding grounds in Northern Ontario, a non-stop flight of about 235 km! She settled in the boreal forest near Shoals Provincial Park. She departed at the end of October and used the straits again, this time flying over Bois Blanc Island. Her last signal indicated she was just north of Grayling, MI.
Out of all our MI tagged birds, Trinity has bred the furthest north. She bred in Northern Ontario just southwest of Polar Bear Provincial Park! This was amazing to see since this habitat is essentially open tundra with probably a slim selection of large trees to nest in which is what these birds prefer. Trinity departed near the end of October and also used the straits area once again. She crossed over Mackinac Island. Currently she is near Hustonville, Kentucky approximately 1,800 km from her breeding location.
She decided to settle and breed right on the edge of the boreal forest in Northern Ontario about 85km northeast of Hearst. Sam also used the straits area during her fall movement crossing at Saint Martin Bay and then flying over Bois Blanc Island. Sam is currently following closely behind Trinity and is currently north of Aberdeen, Indiana. It looks as though she will be heading towards Kentucky as well. She is roughly 1250km from her breeding grounds.
We actually just received data from Morpheus last week for the first time since mid-April. Morpheus also bred in Northern Ontario. He bred in what could be described as Hudson plains habitat just like Trinity. Morpheus was about 60km southwest of the first nation town of Attawapiskat, Ontario. This is another amazing breeding location to document. We currently do not know Morpheus’s current location, but hopefully in the coming weeks we will get the rest of the backlogged data from the summer.
Patagium: When we first reported on Patagium we thought she had initiated her migration after hanging out near Villebois in Quebec for a few days in early October. It turns out she would end up flying back and forth between Villebois and her breeding location another 4 times before initiating her migration around Oct 17th. She is currently near Elliot Lake in Ontario and appears to be heading to the Straits region again. It will be interesting to see where she crosses.
Rowan: Rowan has slowly been working his way down through MI over the past month making long stopovers all along the way. As of yesterday, he is just south of Montpelier, Ohio. It appears he has found some nice fragmented forest patches mixed with agricultural fields. It will be interesting to see how much longer he takes to reach his winter territory.
Most of our birds are back on the grid as they finish their fall migration. As a result, we have breeding locations to share – perhaps the most exciting of which are the dark putative ‘non-harlani‘ birds.
Below are the breeding locations for the remainder of our tagged harlani, as well as individuals we tagged in Kansas last winter as an effort to better understand the breeding origin of dark birds wintering in the Great Plains.
Unfortunately, the third dark morph we tagged last winter is the one bird we have not heard from yet this fall. But, we last received locations when it was headed into Alaska, so we can be reasonably sure it is a breeder from that area.
As you can see, the dark birds we tagged that lack typical harlani characteristics, including the first two birds in our study, breed in sympatry with harlani. This is exciting, but not entirely unexpected. We knew before that these types breed in Alaska from our observations at Gunsight Mountain, Alaska during spring migration (Check out this collection of photographs), and from observations on the breeding grounds (see Bryce’s observations near Anchorage), and a bird very similar to Hathor that Rob Domenech tagged that bred near Wasilla, AK.
Does this mean they are harlani? Or are they intergrades? If so, intergrades between which taxa? Or is the explanation much more complicated? These are unanswerable questions at the moment, but luckily we have the blood samples to do genomic work that should help us understand things. No matter what the explanation, it is sure to be interesting.
There are many plumage characteristics that separate these dark birds from what we consider typical harlani plumage. Perhaps the most striking is the tail, as you can see in the image above that illustrates the diversity in tail plumage that can be found in Red-tailed Hawks breeding in this area of North America. If these are all part of the same subspecies, harlani, then it increases the phenotypic diversity in this taxon to an incredible degree. In that case, it begs the question of why and how such diversity is maintained in this population, and not others. To help understand this, we plan to add more samples to see if this pattern holds, and to start digging into genomic data for the samples we already have. Some exciting stuff ahead, so keep checking in for more updates.
Hi, everyone! My name is Allie, a graduate student at the University of Minnesota Duluth. Here in Duluth, fall migration is incredible, featuring high numbers of Red-tailed Hawks showcasing different plumages. Dark morph Red-tailed Hawks migrating and wintering in Minnesota are especially beloved by the raptor community.
Why is this?
Well, dark morph Red-tailed Hawks are not very common east of the Rocky Mountains. Western subspecies, like B.j. calurus and B.j. harlani, are polymorphic, meaning individuals can present dark, light, and intermediate plumages. In Minnesota, and all throughout eastern North America, Red-tailed Hawk subspecies, like B.j. borealis and B.j. abieticola, are currently known to be essentially monomorphic – only presenting variations of light plumage. Nevertheless, there are dark morphs observed during migration/winter in eastern parts of the Red-tailed Hawks’ geographic range. Thus, their rare presence is treasured and begs these two questions…
Which subspecies do these dark morphs represent, and where are they from?
In collaboration with Hawk Ridge Bird Observatory, I am collecting genetic material from all dark morph birds captured at Hawk Ridge in order to determine which subspecies they are more closely related to. Additionally, I am deploying satellite transmitters on three adult dark morph Red-tailed Hawks captured in Minnesota during migration or on the wintering grounds.
Featured below are the two birds we’ve deployed transmitters on. Manley (a second-cycle bird) was captured in Savage, MN in February and Trudi (an after third-cycle bird) was captured close to Duluth, MN last week. So far, we know Manley has summered (but probably did not breed) in northern Manitoba, and Trudi has made it as far south as Indiana within a few days! Here’s hoping we will get a better picture of their full annual cycle over the next several years. Stay tuned!