Hawk at 12 O'Clock! The Pechinegro Migration in Costa Rica Arrives Again

Our immediate area is a way station every year at this time for the migration of the Pechinegro hawks (aka Black-Chested Hawk). This annual migration always occurs mid-March and this day in 2015 is the 5th year in a row we've spotted them. 

About 300 large hawks circling the rocks
2015 First Arrival of the Black-Chested Hawks

Many of our neighbors know about this annual rite, but they failed to tell us when we purchased our property back in 2007. What a great bonus is this spectacle! I'm not sure how we missed them in 2009 and 2010, but each year we keep our eyes out for them starting about May 10th. 

Not every year is as spectacular as the first year we saw them. Back then, it seemed they all came as one huge flock, thousands of birds. They perched in the trees on our farm and neighboring farms. Subsequent years, they have come in several smaller flocks, only a few hundred at a time. Below is the description of the 2011 migration:

We were treated to one of Nature's memorable spectacles yesterday soon after we returned home about 4 PM. We noticed a few more birds than usual flying overhead. At first, we thought they were grey vultures, which are common here. Then we noticed a few more and then a lot more circling our little valley cul-de-sac. Within 15 minutes, there were, by my estimate, a minimum of 500 to a 1000 birds in the air. 

Fraction of 2011 huge flock of Pechinegro Costa Rica
A Fraction of the 2011 Flock

I don't have a suitable wide-angle lens, so the birds you see in the 2011 photograph are just a fraction of the entire group. I didn't know what they were at first, but some flew close enough that I could see that they were definitely not vultures. It took us a while to identify them, partly because there is a lot of variation among individuals. Not all of them actually have black chests for instance.

I waited patiently with binoculars for single birds to sweep by with my Guide to the Birds of Costa Rica close by so that I could compare them to the plates. Clearly they were hawks, but which species?

At last my patience paid off. A lobe of the swirling, drifting mass of birds wandered over our house, and I got a detailed look at them. Gavilán Pechinegro, aka Black-chested Hawk, aka Barred Hawk, aka Prince Hawk. These are not small birds. They measure 24 inches head to tail, and weigh about a kilo each. My cat better not mess with them!

As twilight settled over our mountain, I could see that the hawks were beginning to settle into the trees across the ravine. In another 10 minutes they were starting to settle in the trees in our upper forest. They were still about 200 meters away, however.


A Juvenile Pechinegro Perching in Our Trees
 Tamara and I stealthily made our way up the back road to see if we could get a closer look. They were rather wary of us, so the shots below were about the best I could do with the camera's optical zoom all the way to 12X. If we came closer, they took off to join the larger group again.


Occasionally, one or  a few would swoop very close over our heads from the trees above. I was amazed at the size of them. The Pechinegro is known for its large wingspan.
  

I can only wonder at the purpose of these kinds of mass migrations of birds. They don't typically hang out in flocks. My guide book doesn't mention this phenomenon at all, so for us it's still somewhat of a mystery.

Is it just that their timers all go off at the same time, or is there some reason why they need to stick close together as they make their expedition to their wet season hunting grounds?  
 

I missed their dawn departure the next day by about 15 minutes because I slept in a bit. Tamara said that before 6 they were already flying out in a long serpentine line heading toward the coast. I thought I spotted a few stragglers, but they could have been the local vultures. Too far away to tell.

A treat indeed, even though it's a harbinger of Costa Rica's Emerald Season, which I don't really mind as long as it's not a deluge like last year!  

One of the delights here in C.R. is the change of "seasons", which includes more than just a transition in the weather. Even within dry and wet seasons there are many subtler signs of change such as new species of animals or insects coming and going though not always in such spectacular fashion as these mass bird migrations in Costa Rica.

Ciao cacao!

3 comments:

  1. My husband and I enjoy spotting birds here in Puriscal as well. We really enjoyed your post about the Hawks.

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  2. This is so cool!

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  3. That was Amazing to get to see so many raptors.

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Thanks so much for your comment! - Casey

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