migrating hawks...
FYI: I love hawkwatching more than maybe any other kind of birding and have written several other blog posts about hawks. I wrote about hawk migration here: view link
And I blogged about identifying hawks in flight in a “2-part” blog post here: view link
And here: view link
If you’re at the right place at the right time in the fall you can witness one of the world’s great wildlife spectacles: the sight of hundreds or thousands of migrating hawks moving past the same location. Probably the world’s most incredible hawkwatch site is in Veracruz, Mexico. As millions of hawks of many species migrate through Mexico, there are mountains and oceans to contend with. Just like human glider pilots, hawks don’t like to fly over mountains and oceans because they can’t soar very well. Those topographic features don’t tend to form the coherent columns of rising air, called thermals, which are great for soaring. So as the non-mountainous land mass of Mexico narrows to a thin band at Veracruz, the hawks are concentrated like liquid in a funnel.
Hawkwatchers have counted over one million hawks in a single day at Veracruz! You can learn more about this amazing place here: view link
Why count hawks?
Hawks are vitally important predators (though many hawks are also preyed on by other hawks and owls). And like many birds their numbers are declining due to habitat loss and alteration, window strikes, climate change, etc. Hawks are more strongly affected than most other birds by collisions with cars and trucks because they hunt the roadside berms. And by electrocution on unshielded power lines, particularly in the western US, because they can “complete a circuit” between two wires due to their larger size.
Of course, the Bald Eagle, Peregrine Falcon and Osprey were all almost exterminated due to DDT. Now their populations have come back somewhat since we’ve stopped spraying it here, and these are considered “conservation success stories.” However, our pesticide manufacturers are happy to keep selling DDT south of our borders where many hawks spend the winter.
Because of these many threats to their survival, we need to know as much as possible about how many of each hawk species there are and whether their numbers stable or declining.
Hawk counting challenges
But hawks are not easy to count! It’s very hard to find them when they’re nesting, especially in forested areas. This is time-consuming work that takes a lot of skill, so there’s comparatively little of it going on even though what we learn in this way is extremely useful. So our Breeding Bird Surveys can’t quite do the job. Nor can our Christmas Bird Counts (CBCs), because many hawks have left our area by that time.
So the idea is to count the hawks when they migrate. Naturally we miss most of them. But by standing in the right spots consistently at the same times in fall (and also in spring in some places), across the whole continent, we can collectively develop some sense of whether hawks are holding their own or not.
That’s how most hawk counting has traditionally worked in recent decades: thousands of skilled but mostly volunteer observers in thousands of locations reporting their “citizen science” observations to organizations like the Hawk Migration Association of North America (HMANA) and Hawkwatch International. Gradually this data collection has become more systematized and the large-scale picture of hawk migration has become clearer. At the same time, it’s become more painfully obvious than ever that we don’t have the data we need to support smart decision-making to protect hawks nationwide.
The Raptor Population Index
The Raptor Population Index (RPI) project looks to take the aggregation and analysis of all that data that’s been accumulating to a new level. RPI is a partnership between three of North America’s key hawk migration research organizations: Hawk Mountain Sanctuary, HMANA and Hawkwatch International. Here’s a link to the RPI website: view link
RPI’s vision is to “…contribute to effective conservation of migratory raptors through continent-wide, long-term monitoring of raptor migration, scientifically sound assessments of population status, and public outreach and education.
How will RPI accomplish that? By:
* Producing statistically sound data on annual populations and trends for each hawk species from as many count sites as possible
* Update population status assessments much more frequently than has been possible in the past
* Make the data more widely available than it has in the past
Sounds like same-old-same-old at first glance? It’s really not. RPI creates a mechanism that hasn’t existed before -- to collect data from all those wonderful monitoring sites, and archive it permanently in a centralized, digital database. Amazingly given how important and much-loved hawks, eagles, etc. are, this has not existed til now. (Which shows you how little money is available for conservation work versus, say, collecting data about your spending habits so you can be annoyed by telemarketers during dinner.)
Of course, RPI isn’t just going to store data -- it’s also going to analyze it. The point, after all, is to estimate populations and trends, regionally and continent-wide, for everything from cute lil’ American Kestrels to breathtaking Golden Eagles.
Also far from a no-brainer is the task of making all this trend analysis and associated available to the general public, the scientific community, and various local, state, federal, etc. agencies.
How RPI will work
The first step is to aggregate the data. Most of this data is on paper forms and must be transferred to an electronic format by hand, yipes! As that systematically happens, analysis can begin. A statistical model has been developed that can detect and quantify population trends from our long-term migration count data. The first data sets that will be analyzed with the model are those gathered by ongoing, consistent, annual, long-term studies. Rougher data sets will be processed later.
Hawkcount.org
Meanwhile, the new online information system at HawkCount.org will collect data from RPI project sites, so that data will be in digital format right from the start. HawkCount.org will both archive new data and also make it much easier for citizen hawk counters to enter their “official” data.
All this is very exciting to hawkwatchers and other conservationists! If you’d like to help count hawks for RPI, check out the RPI project website, the Cornell Lab of Ornithology, or your local Audubon society or bird club.
Peace and good birding,
Scott Cronenweth
Eons birding mentor
www.naturalpathwalks.com
