This Hawk Climbs Trees For Some Reason

0:00 What if I told you that today's beast flies, hangs upside down, and eats fruit?

0:06 What creature would you think it is?

0:08 A fruit bat seems like the obvious choice,

0:11 but there are a bunch of tropical birds that fit the bill, too.

0:14 Heck, even a sugar glider kind of makes sense

0:17 if you keep your definition of flying a little loose.

0:20 Now, what if I told you it's none of those things?

0:24 It's a bird of prey, a so-called raptor.

0:28 Not what you pictured, right?

0:29 But why not?

0:31 What even defines a raptor, anyway?

0:41 The Bizarre Beast Pin Club is open for subscriptions for the whole month.

0:44 Sign up by May 20th and your first pin will be one of these weird birds of prey.

0:50 The African Harrier Hawk, a member of the Accipitridae family,

0:54 can be found all over tropical Africa south of the Sahara,

0:58 from rainforests to deserts to human settlements.

1:01 They have about a 1.2 to 1.5 m wingspan,

1:05 making them the biggest hawk species in all of Africa,

1:08 and the females are typically larger than the males.

1:11 Their biggest standout features are their featherless face and long legs,

1:16 both of which help them with some of their unique foraging methods.

1:20 Their prey isn't that out of the ordinary, though.

1:23 They mainly eat small vertebrates like lizards, mammals,

1:26 and birds, as well as eggs and hatchlings.

1:28 But they also eat oil palm fruits, which is a little offbeat for a bird of prey.

1:34 Raptors are generally considered hypercarnivores,

1:37 meaning that their diet consists of at least 70% meat.

1:41 So sure, snacking on fruit here and there isn't out of the question,

1:45 but of the over 500 species of raptors in the world,

1:49 only a little over 30 have actually been observed doing this.

1:52 The African Harrier Hawk's diet has, in at least some cases,

1:56 been measured at about 13% plants on average,

2:00 which still puts them past the 70% meat cutoff for hypercarnivore status.

2:05 But they've also been observed eating a diet of up to 86% oil palm fruits,

2:11 and some folks might call you a straight-up frugivore at that point.

2:15 Raptor species that have been spotted eating fruits seem

2:17 to mostly opt for those with a high fat content,

2:20 which could just be a convenient substitute when prey is hard to come by.

2:25 Still, this doesn't totally explain why birds

2:27 like the Harrier Hawk or its neighbor, the Palm-nut Vulture,

2:31 have a more frequent affinity for this behavior than most raptors.

2:35 It may simply be that these species are

2:37 more visibly exploiting an available resource than their relatives,

2:41 who themselves might actually be eating fruit more than we realize.

2:44 When hunting its non-fruit food options,

2:47 African Harrier Hawks can soar about 30 to 100 m above

2:51 the ground to spot prey before zooming down on a target,

2:54 or they may hunt by scanning an area while perched at a high vantage point.

2:59 Fairly standard stuff.

3:01 But they will also fly around much closer

3:04 to the treetops and allow themselves to be mobbed.

3:07 Mobbing is when smaller birds squawk at or even

3:11 attack potential predators to drive them away.

3:14 Not usually a pleasant experience for any of the parties involved.

3:18 But the African Harrier Hawk actually uses the intensity

3:22 of mobbing as an indicator of where prey nests might be.

3:26 They seem to actively seek out the most aggressive mobbing

3:30 and even turn back around when things calm down again.

3:33 It's like warmer, colder, but with bird violence.

3:38 And what they do once they home

3:40 in on their target is probably their coolest characteristic.

3:43 Because, as strange and interesting as all

3:46 this fruit eating and songbird antagonizing may be,

3:50 it still doesn't explain that little bald face or those lanky legs.

3:54 Instead of diving and crabbing and other regular raptor behavior,

3:59 African Harrier Hawk's specialty is methodically

4:02 rooting out prey that hides in cavities.

4:05 Those featherless faces make it much easier to get all up

4:09 in a hollow tree to snatch whatever edible creature may be inside.

4:14 And if that proves too difficult, their extra-long legs,

4:17 or extra-long feet, really, can do the trick instead.

4:21 This is further aided by their extremely flexible ankles,

4:24 which let them easily rummage around inside of trees to grab birds,

4:29 eggs, bats, or what have you.

4:30 And yes, that prey list does unfortunately include

4:34 the offspring of our cavity-nesting friend, the hornbill.

4:37 African Harrier Hawks reach these types of hollows

4:40 by actually climbing up tree trunks and then hanging,

4:43 often upside down and at other wacky angles, while conducting their searches.

4:48 They also employ these inverted talents to plunder weaver nests,

4:52 which they search and even tear apart while

4:55 hanging in place and flapping their wings for balance.

4:58 Not exactly your textbook bird of prey attack style.

5:01 In fact, African Harrier Hawks are so specialized for this weird way of hunting

5:05 that their eyes don't even work the same way as all of their relatives.

5:10 Daytime hunting raptors have a wide binocular

5:12 field of vision that's great for attack accuracy, attack-curacy, if you will.

5:17 But they have a major blind spot directly above them.

5:20 This makes sense for two reasons.

5:22 They evolved ridges on the tops of their eyes to block out glare from the sun,

5:29 and they don't really need to look up

5:32 when the prey they're hunting is down below.

5:34 African Harrier Hawks, on the other hand,

5:36 totally lack that blind spot and can see above their heads with anywhere

5:41 from 20% to 100% more coverage than any other known Accipitridae species.

5:47 This means that they're better able to see

5:50 what they're doing while ransacking a tree,

5:53 regardless of whether they're right-side up or upside down.

5:56 It's a far cry from the aim for the prey

5:58 you're swooping down on method employed by raptors like we'd expect.

6:02 Looking for a doctor can feel a bit like

6:05 you're an African Harrier Hawk reaching into a tree hole.

6:08 You know what you're hoping to find,

6:09 but there is no guarantee that you'll get what you're looking for.

6:12 So sometimes we just put it off.

6:15 Not because we do not care about our health,

6:18 but more so because of how difficult it is to actually book and see a doctor.

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6:25 and you shouldn't have to reach into any tree holes to find them.

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7:10 So what exactly is it about this handful of traits that makes

7:13 the African Harrier Hawk seem so different from typical birds of prey?

7:18 The better question might be, what exactly is a raptor?

7:22 The truth is, there isn't a formally agreed-upon

7:24 biological definition of raptor or bird of prey,

7:28 and what qualifies is hardly taxonomically consistent.

7:32 The word raptor comes from the Latin word meaning to seize.

7:35 So having crabby talons seems to be the most common through-line,

7:39 and that tracks with the fact that all of the different raptor taxa

7:43 have their own highly adapted talon styles based on what they catch and have.

7:48 But that's the strange part.

7:50 The taxa in question aren't even that closely related.

7:53 The order Accipitriformes, which includes eagles,

7:56 ospreys, hawks, kites, vultures,

7:58 and more, is totally separate from the order Strigiformes, the owls.

8:03 And Falconiformes is closer to parrots and other

8:06 perching birds than to either of those.

8:09 The usually defining adaptations that make a so-called raptor,

8:13 great eyesight, a sharp beak, and those mean talons,

8:16 all basically amount to a set of convergently

8:19 evolved tools for finding and eating meat.

8:21 Simple as that.

8:22 Which is still plenty true for African Harrier Hawks,

8:25 but instead of eagle strength, owl stealth, or falcon speed,

8:29 they evolved dexterity for opportunistically hunting more stationary prey.

8:33 As with many of our favorite beasts, they simply evolved to exploit a niche.

8:38 Amazingly, the exact same can be said

8:40 for the Crane Hawk from Central and South America,

8:43 which has the same double-jointed tree cavity hunting style,

8:47 and it's not closely related to the Harrier Hawk at all.

8:51 Just more convergently evolved coolness.

8:53 So really, having specializations best suited

8:56 for its distinct predatory style actually make

8:59 the African Harrier Hawk a very suitable fit for the bird of prey club.

9:03 Eating fruit and climbing trees may

9:05 not follow our traditional raptor assumptions, but that's more of an us problem.

9:10 Ultimately, this is just another example of humans

9:13 creating boxes purely for our own convenience,

9:16 even when those boxes don't necessarily have much meaning in nature.

9:20 Very often, the labels we create are entirely vibe-based.

9:24 Just ask any botanist what counts as a pumpkin.

9:27 What makes the African Harrier Hawk unique from other birds of prey

9:30 doesn't actually mean it's not still a bird of prey itself.

9:34 Though to be fair, the sight of a hawk scaling a tree or flopping

9:37 around with one foot in a hole is a bit bizarre on its own merits.

9:42 But this beast is simply living its best raptorial life,

9:46 even if it has to stretch the definition of the term just as far as its legs.

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9:52 at bizarrebeastshow.com and help keep this channel going.

9:55 If you want an African Harrier Hawk to be your first pin, sign up by May 20th.

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10:19 And now for some bonus facts.

10:24 Along with being great for sticking into tree holes,

10:27 the African Harrier Hawk's naked little face also lets us see them blush.

10:32 Their bare face is usually a pale yellow color,

10:35 but can flush bright red in a variety of circumstances.

10:39 Generally and unsurprisingly,

10:41 this seems to be something of an all-purpose excitement response,

10:44 including during courting and leading up to mating.

10:47 When nesting, African Harrier Hawk mates typically

10:50 take turns incubating the eggs and hunting.

10:52 They sometimes seemingly disagree when the time comes to swap roles,

10:57 resulting in shoving matches.

10:59 And curiously enough,

11:00 facial flushing seems to correlate with which parent is already at the nest

11:05 and which is returning from hunting and ready to take over.

11:08 While incubating the eggs,

11:09 the parent already sitting at the nest is more likely to turn red,

11:13 while the parent arriving stays pale.

11:16 But once the eggs hatch,

11:17 the parent at the nest stays pale while the arriving parent blushes.

11:21 Both individuals' faces go red during the shoving

11:24 instance until one of them backs down, at which point it goes yellow again.

11:28 These color-changing patterns seem to involve a system

11:31 of challenge and concession between nesting Harrier Hawks

11:35 and could be a form of communication between

11:37 them or just an incidental result of behavioral conditions.

11:41 It may sound like a pretty basic characteristic.

11:44 Skin has blood vessels in it and the amount

11:46 of blood pumped to the surface can change,

11:49 and that can certainly relate to experiences that crank up the heart rate.

11:53 But facial flushing has so far only ever been

11:55 observed in a couple dozen bird species around the world.

11:59 Chalk it up to yet another way that this beast defies bird norms.