The Life of Birds - Finding Partners
Transcript
00:30Oh
01:00This
01:08Lava gull in the Galapagos like all the rest of those birds is sending a very clear message with its call
01:14It's saying I'm ready to mate and I've got a great place for a nest
01:30Some birds send the same message, but use an additional medium not just sound but vision as these frigate birds are doing
01:50Their visual signal is normally an inconspicuous patch of shriveled skin on the throat
01:57It takes about 20 minutes to blow one up
02:11The females who don't have a throat pouch cruise by assessing what is on offer
02:17The size of the balloon gives them a good indication of a male's figure and therefore his desirability as father of their chicks
02:36A female takes a closer look
02:41Males who haven't yet got a nest keep a close eye on developments
02:47The female leaves and one of the homeless males decides to make a challenge
03:04The throat pouch is an obvious target. Tear that and its owner won't be able to attract anyone
03:26A new proprietor takes over the nest site and pumps up his balloon
03:35Success is swift
03:45She's found what she was looking for
03:50A male hornbill's brilliantly coloured beak and wattles is also an indication of his fitness
03:57Having attracted a female's attention, he accompanies her on flights through the forest
04:03and at appropriate moments he cements their relationship with a few judicious gifts
04:16A little fruit
04:19Males worldwide ingratiate themselves with females in this way
04:25Wattled guans do in the tropical forests of Amazonia
04:29and so do great tits in the suburban gardens of Europe
04:34Seabirds, of course, like fish, though it's still the prerogative of the female to decline a gift the first time it's offered
04:48Grebes like fish too. These are on a lake in North America
04:55But for grebes in particular, exchanging presents is only the beginning of courtship
05:01There's a lot of dancing to be done before the partners are sure that they're meant for one another
05:08Their first routines involve repeating one another's movements
05:18One, two, three, four, five, six, seven, eight, nine, ten
05:25Ten, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20
05:3121, 22, 23, 24, 25, 26, 27, 28, 29, 30
05:37Once they've got to know each other really well, however, they perform their pas de deux together with immaculate timing
06:08Their wings don't contribute much to their costumes
06:12Like those of all diving birds, they're short and stubby
06:19But the dancers make up for that with impressive footwork
06:27The grebes are known to be the best dancers in the world
06:32But the dancers make up for that with impressive footwork
07:03After the dancing, more gift-giving
07:07Wee from the bottom of the lake, a sample of what the couple intend to contribute when they make their nest together
07:15After the dancing, more gift-giving
07:19Wee from the bottom of the lake, a sample of what the couple intend to contribute when they make their nest together
07:27Wee from the bottom of the lake, a sample of what the couple intend to contribute when they make their nest together
07:37A male swallowtail gull also declares his intentions with a down payment on the nest
07:48As a pair get to know one another better, they become sufficiently trustful to indulge in a little mutual preening
07:57As a pair get to know one another better, they become sufficiently trustful to indulge in a little mutual preening
08:07Albatross behave in the same way
08:18These powerful bills are quite strong enough to injure anything or anyone that dares to interfere with the birds
08:26But now, as the pair sit together on their nest site, they're used to deliver the most tender of caresses
08:47What follows may seem like duelling
08:51But actually, it is, once again, a kind of dancing
08:59The sequence of movements is long and complicated
09:21If both partners perform without mistakes and in harmony, then, at last, there comes the most intimate act of all
09:33If both partners perform without mistakes and in harmony, then, at last, there comes the most intimate act of all
09:41Mating in birds can be a very quick business, no more than a brief meeting of genital openings
09:47In albatross, it's unusually leisurely
10:01So, pairs are formed, and the union of the pair is formed
10:11For most birds, the pair will now stay together for several weeks, if not for several years
10:18In the case of these waved albatross in Galapagos, they'll stay together for the rest of their lives
10:23And that, when you come to think of it, is very unusual
10:27Insects don't stay together, frogs and toads don't, lizards and snakes don't
10:33Why should birds?
10:35The answer is there
10:40No female bird can manage to fly around with an egg inside her, let alone several, for the days or weeks it needs to develop
10:48As soon as she can, she lays it
10:51But then, caring for it is a major job
10:54And for these albatross, as for most birds, it's a job for two
10:59It would be nice to think that such a devoted pair was held together by mutual affection
11:05The evidence, I'm afraid, doesn't support that
11:08It's not so much the affection that one bird has for the other
11:12As the concern it has for its own genes, which are in the egg which the two produce together
11:18If, without jeopardising those, either bird could find a way of spreading its genes more widely
11:25The evidence suggests it would take it
11:31Here in Jamaica, some male birds are far from faithful
11:37Flame trees, when in flower, produce great quantities of delicious sweet nectar
11:43It's the staple diet for hummingbirds, and Jamaica has many different species of them
11:49The male streamer-tailed hummer is a vigorous and aggressive creature
11:54And a particularly strong individual will take control of an entire tree
12:07Other males, of course, have their eyes on it
12:12But the resident male won't allow others near his flowers
12:16Even though he might think there is more than enough for everyone
12:21But he's not fighting just because he wants to drink all the tree's nectar himself
12:27He's more devious than that
12:31The tree is the most prolific source of nectar around
12:36There are several female streamer-tails in the nation
12:39But the male is the most prolific
12:43The tree is the most prolific source of nectar around
12:47There are several female streamer-tails in the neighbourhood
12:51And they're busy building nests, which they do entirely by themselves
12:55They're relatively plain creatures, lacking the long streamer-like tails of the male
13:04There's so much nectar around that when the time comes, they will be able to feed their chicks single-handed
13:11But the main supply comes from the flame tree
13:14And sooner or later, they all visit it
13:19The male streamer-tail waits for them to call
13:24As soon as one appears, he shows off in front of her with a special courtship flight
13:32He erects little tufts like ears on either side of his head
13:42She accepts him
13:47He goes back to wait for the next diner
13:51While she pulls herself together and prepares for life as a single parent
14:00A good, secure home can also be a very effective lure with which to attract a female
14:06Red-headed weavers in Africa often nest in colonies
14:09And when they do, the females, who have yellow heads, keep an eye on which male is building what before committing themselves
14:18This one is only just starting
14:20It's too early to judge his skill as a builder
14:24This looks promising, but perhaps it's still too early to tell
14:40A lot of work goes into each nest
14:43It's very important that the weave should be tight
14:46If it's too loose, the eggs might drop through
14:55When one is finished and ready for judging, the male perches hopefully beside it
15:10She clearly doesn't think much of this one
15:25This, however, is good enough to warrant an internal inspection
15:29If she accepts, she will add the lining herself
15:34But there are lots of females around, and as soon as she's settled in, he starts building another nest
15:41In fact, this particularly skilled and industrious male has already built three earlier nests
15:47Each of which now holds chicks that he has fathered
15:53Each female, by choosing him as a mate, has provided her young with the best genetic inheritance possible
16:00And he, by keeping on building, has quadrupled the number of his offspring
16:07But some birds construct even bigger buildings to impress females
16:11And to see the most spectacular of all, you have to come to the dense forests of the islands north of Australia
16:20Some females can be persuaded to mate for rewards that are more abstract than merely the size of the nest
16:27There's a kind of bird here in New Guinea whose females select a male not because he's a better meal ticket
16:34but because he's a better artist
16:36How else would you describe this wonderful construction except as a work of art?
16:46This is its creator, the Vogelkop bowerbird
16:51He has a passion for interior decoration
16:54His hut, almost big enough for me to crawl into, is neither a home nor a nursery
17:00It's a gallery in which he can display his artistic creations to visiting females
17:08These flowers come from a creeper that has only just started to bloom
17:14Great new material for anyone who likes colour, and he loves it
17:33The iridescent wingcases of beetles also appeal to him
17:38The iridescent wingcases of beetles also appeal to him
17:42and he's amassed an impressive collection
17:44But they're always in need of a little rearrangement to show them off to their very best advantage
17:53He calls to invite female visitors
17:59There are several such bowers in this part of the forest
18:04A hundred yards away, there's another one, built by another male of the same species
18:09who has a slightly different artistic sense
18:13If a female decides that this is the best selection of jewels, then she'll mate with the owner
18:20So here, where living is easy, a female is not bowled over by practical things such as food or accommodation
18:27It's beauty that wins her heart
18:30And beauty can be found not only in jewels, but in costumes
18:39This is Bulwer's pheasant
18:42And this is Bulwer's pheasant
18:46This is Bulwer's pheasant, and he has got spectacular wattles
18:52He's impressive enough when he's going about his normal business
18:55but when she is around, he gets very excited indeed
19:16Impressive though he is, she is very critical
19:25He's not good enough, it seems
19:30Another pheasant, Temink's tragerpan
19:33His costume jewellery is even more elaborate
19:37And if you've got it, why not flaunt it?
20:08The male moanowl pheasant impresses his female with a greater expanse of unbroken iridescence
20:14than is possessed by any other species
20:18The male moanowl pheasant impresses his female with a greater expanse of unbroken iridescence
20:24than is possessed by any other species
20:48The Argus pheasant has the largest of all tail feathers
20:52and wing feathers that are certainly as spectacular
21:04And what can rival the train of a peacock?
21:11The costume put on specially for courtship dances by the Argus pheasant
21:16Courtship dances by the African widow bird may not be quite as extravagant and unwieldy as those of the pheasants
21:24But the widow bird displays by flying with his
21:38It's a hazardous business, exposing yourself like this even if you can fly
21:43You're making yourself an easy target for a hawk
21:46and there are many around on these grasslands in Kenya
21:54Evidently, the additional matings a male gets from displaying in this dangerous fashion make the risk worthwhile
22:02Up in the frozen north on the Arctic tundra, life is altogether too rigorous to allow such extravagance
22:09Here, males display in a more modest way
22:16The buff-breasted sandpiper. No spectacular plumes for him
22:21But he's a man of his word
22:24The buff-breasted sandpiper. No spectacular plumes for him
22:37But nonetheless, he has quite an attractive armpit
22:43Flashes like these can be seen a good 200 yards away
22:48A female has got the message
23:01She's definitely interested
23:13Now there are three females. It's time to reveal all
23:27He reinforces his appeal with quiet, clicking calls
23:35More and more females
23:42More and more females arrive
23:51Nearby, another male is having no success whatsoever
24:01Now there are four females with male number one. This hardly seems fair
24:07There must be something about number two's underwings that doesn't appeal
24:13So he comes over to where the action is
24:23The females don't know which way to turn
24:42But number one won't allow anyone else on his pitch for long
24:46There's not room on this part of the tundra for two
25:04So competing for mates only too often leads to physical violence
25:13Scotland. Here, in the pine forests of the highlands, fights between males are among the most violent of all
25:27The capercaillie is the biggest of grouse
25:31The arenas on which the males display are vigorously contested
25:35And the best, in the end, is claimed by the most powerful male, who will defend it against any intruder
25:54He is the most powerful male
26:00So charged up, this being the breeding season, that he will display to almost anything, including me
26:10No bow, no bow
26:25But here's a really serious rival
26:31He is being very reckless indeed
26:54Birds can get very badly injured in battles like this
27:00And even die from their wounds
27:02But the rewards they're fighting for are very great
27:05This is the most important moment of their year
27:19The females tour the duelling grounds to select the bonniest fighter of them all
27:25And they seem to agree on who the champion is
27:39Runners-up are almost universally rejected by the females
27:43While the winner attracts almost more mates than he can deal with
27:55Some males make the job of the females in choosing between them easier
28:00By gathering together and displaying in groups
28:03And there's one bird in the canopy of the Brazilian rainforest here
28:07Who has perhaps the oddest way of trying to impress a female
28:12It's called the calf bird
28:25They compete with calls
28:28The sound is greatly amplified by air sacs on their throats
28:35The skin surrounding the sacs is so thin that as they inflate, they can't be heard
28:41And they can't be heard at all
28:44The sound is so thin that it's hard to tell the difference between a male and a female
28:50The skin surrounding the sacs is so thin that as they inflate, you can see right through them
29:05This assembly is a hundred feet above the ground, high in the canopy
29:09So high that very few people have ever seen the birds performing this extraordinary chorus
29:14Let alone film it
29:21The top male, with presumably the best voice, occupies the best site
29:26A forked branch, totally free of leaves
29:36The females look exactly the same as the males
29:39As you might expect, the male is a little bit taller
29:42And the female is a little bit shorter
29:46The females look exactly the same as the males
29:49As you might expect, since the males are not using special costumes to compete with one another
30:00When a female flies down to the best branch, all the males call with renewed intensity
30:16More females arrive
30:32A female tells the male she has chosen him by giving him a peck on the neck
30:39She flutters to the other branch invitingly
30:43But he's concentrating so hard on his display that he doesn't seem to notice her
30:52She tries again
30:58That's the idea
31:03And then he notices a second female
31:06Call as they might, none of the males on other branches get a look in
31:15The calf bird has a cousin whose males also display in groups
31:19They compete not with sound, but with colour
31:23The cock of the rock
31:37The males assemble in groups of a dozen or so, perching low down on lianas
31:42Watching out for females and squabbling among themselves
32:07The female is dull-coloured, she has no use for bright feathers
32:15Her arrival beside the display ground has an immediate effect
32:20The males flop down
32:22Each one owns a particular pattern
32:25The male is a little bit shorter
32:27The female is a little bit shorter
32:29The male is a little bit shorter
32:31The female is a little bit shorter
32:33They flop down
32:35Each one owns a particular patch of ground he's caught
32:38On which he and he alone displays
32:46Each now has the problem of how to persuade her to land beside him
32:51And the cock of the rock's idea for doing that is to bounce competitively
33:03They adjust their positions slightly to try and stay in a patch of sunshine if they possibly can
33:18Once again, a peck on the neck says, I'm yours
33:24And once again, the male is not very quick on the uptake
33:29But he gets there eventually
33:33After this is over, she will go off and rear her chicks by herself
33:42Another female
33:48She makes exactly the same selection
33:59By gathering together, the males make sure that the females know where the marriage market is
34:06But the price of doing so is that only one or two males will make a sale
34:14In just a few species, however, the males in a neighbourhood don't compete with one another
34:19But collaborate to form a team
34:22This is the blue mannequin
34:25He is captain of this team and he whistles to summon the other members
34:37The team is complete and the show begins
34:42They're striving to prove that they are the best team of acrobats in the neighbourhood
34:49A female arrives
34:51She is going to get a close-up view of the performance from the actual dancing perch
34:58If she's sufficiently impressed, she will mate with the captain
35:02But why should the assistants help him?
35:05Because if something happens to the captain, one of them will have the chance to inherit his position
35:10It may not be a large chance, but it's better than performing solo and having no chance at all
35:22That's enough to show how expert they are
35:25So the captain dismisses his assistants with another special call
35:35If the lady decides to accept the invitation, the male will have the chance to inherit his position
35:41And if the lady doesn't, the male will have the chance to inherit his position
35:47If the lady decides to accept him, she will mate with him nearby
35:52She will then fly away and he will just keep on dancing, hoping for another success
35:58He will never knowingly see his offspring
36:01But not all polygamous birds are so neglectful of their parental duties
36:06Here on the pampas of Argentina lives another male with many wives
36:11Here on the pampas of Argentina lives another male with many wives
36:14Who takes his nursery duties very seriously indeed
36:20These eggs are all looked after by one single male
36:25And even now, he's trying to entice another female to come here to add another egg to this huge clutch
36:33He's a rhea, a South American ostrich
36:36And he's mating with one of the group he's managed to attract into his territory
36:40Tomorrow, she will lay
36:45The whole party now moves towards his nest
37:02He settles down to continue incubating
37:11And one of the females with whom he mated yesterday is now ready to lay
37:29She settles down within a yard or so of the nest
37:37An egg is on its way
37:41She settles down within a yard or so of the nest
37:48She leaves
37:51And he rolls her egg into the nest to join the rest of his collection contributed by his other wives
37:58He may accumulate as many as 40 of them
38:05Because the male has taken total charge of the nest
38:08The females can be just as promiscuous as he is
38:11And that female, having laid here, will now be going away to find another male with another nest
38:18To see if he'll accept another egg
38:22That's unusual behaviour for a male
38:25Taking total responsibility for incubation and for chick rearing
38:31On the tundra of the Arctic, however, another species has taken this reversal of roles further still
38:42These are red phalarims
38:46Red phalarim
38:55In almost any other species, you would be right to think that the bird with the brighter markings on its head and neck is the male
39:05And that judgement will be reinforced when you see two brighter birds fighting in front of a duller coloured one
39:12That's typical male behaviour
39:16But the truth becomes apparent when you see them mating
39:21It's the duller coloured one who mounts on the other's back
39:24It's the duller one who is the male
39:34That is the female
39:39He now goes away to the nest that he has already built
39:44The brighter coloured female comes back to him for several days thereafter
39:48To mate again and to add more eggs to the nest
39:54While she sits, he stands aside
40:06Now it will be up to him and him alone to incubate the eggs and look after the chicks
40:13No one really understands why the phalarims, almost alone among birds, have reversed the role of the sexes
40:24But mating openly with multiple partners is the exception
40:28In most species, both male and female are needed to bring up the young
40:32So most birds, after mating, stay together as a pair, at least during the breeding season
40:39An indication that this is the basis of their relationship is that the sexes are broadly similar in appearance
40:47But even so, living as a pair doesn't preclude a little infidelity now and then
40:54Perhaps the most bizarre behaviour of all takes place in the suburban gardens of England
41:02And it seems that until very recently, nobody even noticed
41:09A young female head sparrow, a dummock, ready to lay
41:18This is her mate, Alpha, singing lustily
41:21Declaring his ownership of the nest and the territory around it from which he gathers food
41:29The pair often feed together, a devoted couple if ever you saw one
41:39He seldom lets her out of his sight, for she is not as faithful as she might be
41:49There's a third bird around, Beta, another younger male
41:55He's not popular with Alpha, and they're continually squabbling
42:00Sometimes the fights can get quite vicious and feathers fly
42:09But in spite of that, Beta stays around, skulking in the hedge
42:20Alpha, it seems, doesn't care
42:25Alpha, it seems, has the female to himself once more
42:30But she has got her eye crocked
42:34Beta is still in the hedge, calling quietly to her
42:45She joins him, and now, while Alpha is preoccupied with feeding
42:50She and Beta get together
42:53Twirling her tail is an invitation, and in a split second they mate
43:03Beta flies away
43:06But now, out in the open, she is courting Alpha with that same old tail twirling
43:13He takes precautions to ensure his paternity
43:17He pecks her genital opening
43:33And she eventually ejects a droplet, it's Beta's sperm
43:40He persists for up to three weeks
43:44He persists for up to two minutes, until his rival's sperm is all gone
43:52And now he mates with her
43:54It will be his sperm that will fertilise her eggs
44:01She has kept two males happy, both of whom will help to feed the young when they hatch
44:06And Alpha has managed to ensure that he will be the father of the eggs she will soon lay
44:12Or, at any rate, most of them
44:17But it's here, in the southeast woodlands of Australia
44:21That infidelity reaches its most astounding, indeed you might think its ultimate height
44:30And it occurs among the families of this dazzling little bird
44:37The superb fairy wren
44:42He is an attentive male, courting his female with little gifts of food
44:54But there are other males around, identifiable by the different rings on their legs
45:00One of them dances for her, flaring the blue fans on his cheeks
45:07Yet another male is also flirting with her
45:19And here's another
45:28And she selects one of them
45:37But her first established male is not around to see all this
45:41He is visiting a female neighbour
45:43And what is more, he's carrying a bouquet, a flower petal
45:47Something he never does at home
46:07And his flashy courtship behaviour pays off too
46:14Now he's back beside his own nest and with his first mate
46:18Looking after the chicks that the nest now contains
46:27So, the female fairy wren chooses the flashiest males to father her chicks
46:34And allows her partner only just enough matings to ensure that he helps feed the family
46:39And the males, while they may have chicks in as many as six nests around here
46:45May not have a single one in the nest that they actually tend
46:49They say it's a wise child that knows its own father
46:53But that's never more true than in the bird world
46:57But extreme infidelity, like polygamy, is not widespread among birds
47:03Among swans, as amongst most birds, male and female stay together
47:08And by a combination of bonding with one another
47:11And driving away any who try to interfere with the partnership, they stay together
47:27Male and female conduct their courtship on equal terms
47:31And when they're convinced they're compatible, they work together to build a nest
47:37Protected on most sides by water
47:39And with a strong and aggressive mate to see off intruders
47:43These swans will probably hatch their egg successfully
47:47But for many birds, they are now entering on the most difficult part
47:52And they'll have to employ all kinds of ingenious stratagems if they're to raise a family
47:57As you'll see in the next program in The Life of Birds
48:21The Life of Birds
48:51The Life of Birds