Tag Archive | raptors

Hawks at Palos Verdes

IMG_4662Catherine and I are out in California right now, in the midst of a cross-continental journey we are calling #SpiderTrip2016. This trip has taken us down the east-central part of the country to Austin and further south, where we collected some very colourful black widows  for Catherine’s research.

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Catherine examines a guard rail in southern Texas, where we found black widows in abundance.

 

Right now we are in L.A., where we have been for several days to attend a wedding in Redondo Beach. As the wedding was Sunday night, on Monday morning we went out to find a park to have a picnic and see what we could see. We ended up on the cliffs of the Palos Verdes Peninsula, a region of L.A. that neither of us have visited. This peninsula has some soaring cliffs and beautiful views of the ocean, as well as a great interpretive centre at Point Vicente focused on natural history.

 

As we were eating lunch, the screams of a rapidly diving Peregrine Falcon alerted us to check out the cliffside. While I tried in vain to get a shot of a diving falcon, we clued in to the fact that the falcon was harassing a pair of Red-tailed Hawks nesting on the cliff ledge below.

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This was the best I could manage of these amazingly quick falcons…I did see several dives against the flying hawks, which they countered by rolling and presenting their talons to the approaching falcon. This is not just idle harassment on the part of the falcon either, as they are known to kill hawks during these high-speed attacks. 

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A Red-tailed Hawk, presumably incubating eggs on the cliffside of Point Vicente.

These hawks are well known to the local birders and photographers, and it isn’t hard to see why. Their activities are well in view from the top of the cliffs, and they come very close to the walking path as they provision their nest and ride the updrafts from the ocean winds striking the cliff face.

Anyway, here is a selection of photos I managed to get during a couple hours of watching this incredible specatacle:

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This was the incredible first flyby I managed to shoot of the female Red-tailed Hawk looking right at me as she flew by.

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The contrast of the red tail and the blue sea behind is really quite striking

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Some local birders told me this individual with the broken tail feathers is the male, and it makes sense, as the incubating hawk had an intact tail.

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We saw one of the hawks grab some vegetation from the crown of this palm several times. They would also retrieve sticks from a shrubby slope beneath the cliff.

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The female heads back to the nest with a stick.

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I didn’t know it at the time, but I suspect this dramatic dive was the beginning of a successful rabbit hunt on the shrubby slope. I did not see the kill get made, as it occurred below the cliff.

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One of the pair is engaged in tearing the fur off of the rabbit that they killed. 

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The views of these hawks just cannot be beat, and with falcons, seals, pelicans and more thrown into the mix, you could do a lot worse than to spend some time at Point Vicente! If you are in the L.A. area, I highly recommend it!

 

Weekend Expedition 42: White Christmas in Vancouver?

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A female harrier scarfs down her Christmas sparrow.

Vancouver is generally known for its green wintertime conditions, but sometimes we do get a bit of snow. We had a 10-15 cm dump on Friday morning, which made getting around a bit difficult. I was running errands on the weekend, but brought my camera out anyway, and managed a decent haul of bird pictures out in Delta.

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A harrier on the hunt.

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The birds were not the only ones hunting at Boundary Bay, as about 20 people were out on the mud blasting away at ducks with shotguns, It is more than a little ironic that the place is full of signs telling folks not to disturb wildlife, but shooting at them is A-OK.

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Heron on the prowl for voles.

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A nice little Red-tailed Hawk/

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The eagle disapproves, as usual.

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I was a bit shocked to see a live caterpillar moving along the snow, but I figure it may have been dislodged by a foraging bird.

Do Red-throated Caracaras kill and eat people?

A lesson in how not to infer predation…

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Is this bird plotting a murder?

Red-throated Caracaras (Ibycter americanus) are impressive birds that are  brightly coloured, extremely loud, and travel around the forest in gangs.  They seem to act as if they own the forest, and alarm call vigorously whenever they see you or any other potential threat. I have seen them chase away Harpy Eagles (as have others!), as well as Toucans.

Sounds like a badass bird! If you do a Google Scholar search for “Red-throated Caracaras and Predation“, you might find some surprising things. In the primatological literature, they are listed in several papers (1-2) as being predators of Saguinus mystax, the Moustached Tamarin, a small monkey. This is quite odd, as to my knowledge there is only a single account of Ibycter americanus taking vertebrate prey: Anolis and Ameiva lizards found in the stomach of a single bird shot in Mexico (3).

Certainly, other caracara species, such as the similar, but more distantly related Black Caracara (Daptrius ater) do prey on vertebrates. The Black Caracara has been reliably reported preying on fish (4) and juvenile caciques (5).

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Saguinus mystax. From Wikimedia Commons, User:Postdlf

But the Red-throated Caracara is a different species, with different habits, and is not well-known to take vertebrate prey.

So where does this idea come from?

All the references that I could find about predation on tamarins by Red-throated Caracaras come from a thesis (6) by a researcher named Maria Marleni Ramirez entitled “Feeding Ecology and Demography of the MoustachedTamarin Saguinus mystax in Northeastern Peru”, published in 1989 at the City University of New York. The exact passage about this predation incident appears on page 87 (Daptrius americanus is a former name for the Red-throated Caracara that is no longer used):

“Raptors flying overhead invariably elicited strong alarm responses from the tamarins. Moustached tamarins gave several alarm calls per day that were apparently directed towards birds, thus suggesting that they may be important predators of tamarins. The tamarins’ reaction to attacks by raptors was very strong, as indicated by the loudness and duration of the calls. Daptrius americanus was observed to attack and barely miss a juvenile S. mystax. The moustached tamarins reacted by giving very loud screeches at the same time the Daptrius was diving towards the juvenile.”

Now to be fair, I have been attacked by Red-throated Caracaras (see video), but I never have inferred from this that these birds were trying to prey on me (Although one did strike my ear while I was climbing their nest tree). Or perhaps I didn’t take it personally!

The following video was taken by Tanya Jones in 2009, and shows a group of Red-throated Caracaras diving at me as I climbed their nest tree. I am located right behind the bromeliad; part of my foot is visible below.

[wpvideo yVCCO2E6]

And that is the danger of inferring predation by witnessing one antagonistic encounter between two species, with no video records or stomach contents. Because in my book, predation involves killing and eating the prey, and this was not observed here. In fact, my research, as well as one other study, show that the predominant food items consist of wasp larvae and fruits (7,8), with not a single vertebrate among them. I would not say that Dr. Ramirez’ observation constitutes predation.

'cause doesn't this look better than a monkey?

’cause doesn’t this look better than a monkey?

What I interpret this situation to have been is a mobbing attack on monkeys by caracaras defending a nest site, or merely defending their territory from occasional nest predators. I have seen caracaras chasing Toucans in a similar fashion. I have no doubt that the caracaras could kill, and possibly eat a tamarin (They have an average mass of around 500 g, or roughly the size of a small caracara), but surely some stomach contents would have showed up to indicate such an event. Other than the account of lizards in the one shot in Veracruz,  I can find no such records.

Thus I think that it is definitely premature to list the caracara as one of the “known predators of Saguinus mystax”. Instead, I would probably put the two species in a long list of “animals in the jungle that don’t like each other very much” and leave it at that.

There is still much we do not know about this charismatic bird, or indeed about the trophic relations of rainforest animals in general, but hasty generalizations from a single observation are unlikely to improve matters.

References

  1. Heymann, E., and V. Schaik, 1990. Reactions of wild tamarins,Saguinus mystax and Saguinus fuscicollis to avian predators. International Journal of Primatology 11: p.327–337. 
  2. Lledo-Ferrer, Y., A. Hidalgo, E.W. Heymann, and F. Peláez, 2009. Field Observation of Predation of a Slate-Colored Hawk, Leucopternis schistacea, on a Juvenile Saddle-Back Tamarin, Saguinus fuscicollis. Neotropical Primates 16: p.82–84.
  3. Lowery, G.H., and W.W. Dalquest, 1951. Birds from the State of Veracruz, Mexico. In University of Kansas Publications, Museum of Natural History. p. 556, Lawrence, Kansas: University of Kansas Publications.
  4. Olmos, F., and I. Sazima, 2009. Fishing behaviour by Black Caracaras (Daptrius ater) in the Amazon. Biota Neotropica 9: p.2–4.
  5.  Robinson, S.K., 1985. Coloniality in the Yellow-Rumped Cacique as a Defense against Nest Predators. The Auk 102: p.506–519.
  6. Ramirez, M.M., 1989. Feeding ecology and demography of the Moustached Tamarin (Sanguinus mystax) in Northeastern Peru. PhD Thesis. City University of New York. pp. 87-88 (email me for a copy of the relevant pages)
  7. McCann, S., O. Moeri,
    T. Jones, S.O. Donnell, G. Gries, and S. O’Donnell, 2010. Nesting and Nest-Provisioning of the Red-throated Caracara (Ibycter americanus) in Central French Guiana. Journal of Raptor Research 44: p.236–240.
     (email me for a copy!)
  8. Thiollay, J.M., 1991. Foraging , home range use and social behaviour of a group-living rainforest raptor , the Red-throated Caracara Daptrius americanus. Ibis 133: p.382–393. 

It takes a crazy bird to mess with these gals…

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Social wasps have many dramatic and painful ways of saying” don’t mess with us”, but some animals just don’t take the hint. Red throated Caracaras are one of these foolish/awesome creatures. If you are in Victoria BC this Wednesday, come out to my talk for the Victoria Natural History Society’s Birder’s night to find out more about loud birds messing with painful wasps. 7:30 pm, March 27, Fraser Building room 159.

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Official blurb:

Like the Old World Honey Buzzards, the Red-throated Caracara is a specialist predator of social wasps. Because social wasps are well defended with stings and are avoided by many birds, we were interested in determining how caracaras deal with the defensive wasps. Using video traps to observe caracara predation on social wasps we found that they use several behavioural strategies to avoid wasp defences. Separate work using nest cameras found that up to 7 adult birds were involved in the feeding of a single chick, possibly making the species one of the most social of the Falconidae. Join Sean McCann as he talks about his 5 years of research in the South American rainforest on the unique foraging biology of this species. We meet at 7:30pm in room 159 of the Fraser building. Everyone is welcome. Bring a friend and a coffee mug.

Results of Weekend Expedition 1

A beautiful Long-Eared Owl! One of three we saw, perched together over a ditch.

A beautiful Long-Eared Owl!

This Snowy flew right over our heads.

This Snowy flew right over our heads.

Hidden, but wary!

Bombs away!

Bombs away!

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Another shot of this gorgeous little owl.

The weekend expedition was a great success.  Marie Burle, Willow English, Mike Boers and myself set out for Delta, where the swampy farmland meets the muddy waters of Boundary Bay. . This site is a great place for birds of prey, especially in the winter. We endured cold cloudy weather, but were rewarded with sightings of three owl species, harriers, a Cooper’s Hawk, Red-Tailed Hawks, and many eagles…. The Snowy Owls, which have been abundant at this site both this year and last, were for the most part far off near the shore. We did spot a few, including this one which flew right over our heads. Without a doubt, the highlight of the trip was sighting these wonderful little Long-Eared Owls. Just as we were about to drive away, Marie, a fellow researcher at SFU , spotted the first owl hidden in a tree right next to the car. To our surprise, there were actually three of them perched within 1 m of each other. Shooting was difficult, due to a fence and many blackberry bushes, but we managed to shoot some decent exposures. A brief visit with Sofi Hindmarch, another raptor biologist ended a great weekend expedition.

Results: see above.

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