Week 6: Gannets to Sparrowhawks

Day 21: Blue-footed booby – Sula nebouxii

You know what they say about blue feet

The obvious thing about a blue-footed booby is, of course, its feet. Whilst the rest of the bird is relatively simple and dour, those cerulean feet are bright and eye-catching. I have previously discussed why male birds adopt bright and distinctive ornaments to prove their health and worth in the pursuit of female. Yet, in the case of this booby, both sexes have these flashy ornaments. Well, the argument follows that an individual should compete for a mate when that mate is the limiting factor, i.e. when the mate invests a lot of energy in offspring so cannot reproduce as often. For boobies, and a few other species, just as males compete for females, so females compete for males because the males too invest a lot in the offspring. Essentially this is mutual sexual selection and it is responsible for many of the ornaments found in monomorphic species. Pairs of blue-footed boobies engage in foot-waving dances where both sexes show off their bright, blue feet as an indicator of health and well-being. 

The blue footed booby is a member of the Sulidae which also includes gannets (Morus spp.). I had thought that boobies and gannets were very similar but for their colours and distribution but measuring the family members revealed gannets to be far larger. Gannets are famous for packing on to rocky islands where they compete in huge colonies for space and food. I have seen a gannet colony from afar, both off the coast of Pembrokeshire and adjacent to the Channel Island Alderney. What I didn’t realise was that any gannets I have seen cruising up and down the southwest coast are actually members of one of those two colonies on far-reaching foraging trips. Their ability to traverse huge distances in the search of food makes them robust to local fish depletion. Gannets are famous for their ability to plunge into the water from a great height to grab unsuspecting fish from their shoals. This ability has produced a skull built to absorb shock and internal nostrils to prevent a nose full of sea water. 

Day 22: European shag – Phalacrocorax aristotelis 

Crest the wave Together, shags and cormorants comprise the Phalacrocoracidae. Comorants are a staple of any rocky coastal community where they are often seen perched on the rocks closest to the water. In Britain we have two Phalacrocorax species, the European shag and the cormorant (P. carbo). One might ask what the difference is (and one might get a witty response) but actually it’s a useful question because the two species are not worlds apart. There are clear aesthetic differences with shags being much smaller. Shags are black to metallic green all over except for their bright yellow gapes whilst cormorants tend to be browner with a white cheek patch. The shag is notable for its crest, a great quiff protruding above the. However these visual differences are not the interesting answer. The intriguing question is how two similar species can co-exist. 

The theory goes that two very similar species which share the same home (are sympatric) cannot coexist indefinitely. Either one (the superior competitor) out-competes the other or the species change so that their niches do not overlap as much. The fact that two species of a similar nature do coexist on some shores means that their niches are not (entirely) the same. In the case of shags and cormorants, any birder will know that shags are most often found on rocky shores whereas cormorants are found more in bays, lagoons, estuaries, rivers and inland water. This niche differentiation allows them to occupy habitats in different places however they do overlap in some coastal areas. In this case it is the foraging strategy that differs as shags tend to dive deeper for but for pelagic fish in the water column whereas cormorants dive in shallow waters taking fish from the seabed.. Thus both species exploit different resources and so do not encroach on each other’s niche. We leave the 

Pelecaniformes now, passing the unusual darters (Anhinga), cormorant like birds with serpentine necks. You will have notice and absence of pelicans on the list. All pelicans are in the museums large collection so they will wait for another day. 

Day 23: Lappet-faced vulture – Torgos tracheliotus 

Top of the pecking order

 The lappet-faced vulture is one of a dozen scavenging raptors (Aegypinae) famed for their unsavoury reputation for devouring carcasses. Though perhaps not beautiful to behold they are very impressive birds. This species is one of the largest with a colossal wingspan of up to 2.9 m. To see this flying must be like watching two barn doors flying through the air. I have only seen Old World vultures once, two griffon vultures (Gyps fulvus) gliding through the Pyrenees. These birds were huge and awe-inspring yet smaller in comparison to the lappet-face. On the plains of Africa, smaller vulture species such as white-backed vulture (Gyps africanus) spot dead wildebeest and zebra from miles away and crowd towards the food source all around. 

However once these vultures touch-down next to the carcass they must wait their turn. First the animals’ killer must take its fill. Once the lion or jaguar has departed, scavenging hyaena and jackals move in to fight over the flesh. All the while the white-backs watch on, trying now and then to dart in and seize a scrap. Yet even when the mammals have departed, the white-backs must still wait for it is the turn of the lappet-faces. Though there are few of them in comparison to the white-backs they are far larger and see-off any infringement from the smaller species. However the larger species does provide a service for the smaller, tearing up the toughest bits of the carcass. In the vulture world, lapped-faces are top dog and will not be moved by the lesser species surrounding them. 

Today we began to measure the Accipitriformes (‘sparrowhawk-shape’), a large group of raptorial birds. Traditionally this group has undergone a lot of taxonomic changes due to the evolution of ‘birds of prey’. Firstly it was realised long ago that owls were separate from other birds of prey in their own order, the Strigiformes. The canonical raptors where then housed in the Falconiformes which included vultures, eagles, hawks and falcons. Since the 1980s genetic studies have started to turn up unusual results regarding the group. The New World Vultures were placed in their own family, the Cathartidae, and these were believed by some to be unrelated to other raptors and often placed with storks! The second change was that falcons now seemed to be unrelated, closer kin to parrots! The recently resolved taxonomy has removed some of the ambiguity. The Cathartidae are indeed a separate family from other raptors but they share a common, raptorial ancestor however the falcons are separate and distantly related keeping their order name and leaving the rest of the raptors now named for the genus Accipiter. 

 The Accipitriformes are thus composed of the New World vultures, the secretary bird (Sagitariidae), the ospreys (Pandionidae) and the true raptors (Aquilidae). Most raptors are included in that last family which is split into many subfamilies: elanid kites (Elaninae), honey buzzards (Perninae) true kites (Milvinae), Old World vultures (Aegypinae), sea eagles (Haliaetinae), harriers (Circinae), sparrowhawks/goshawks (Accipitrinae), snake-eagles (Circaetinae), buzzards/true hawks (Buteoninae), true eagles (Aquiilinae) and harpy eagles (Harpiinae). I apologise for the list but I wanted the reader to appreciate the stunning diversity of the raptors and this can act as a reference point for future discussion. 

Day 24: Little sparrowhawk – Accipiter minullus 

Underestimate at your own risk

From one of the largest to the smallest and from the ridiculous to the sublime we reach this tiny bird of prey. My obsession for the superlative meant that I chose the little as my focal species. I like looking at the extremes in a group because by looking at them you get an idea of every possibility in between. Additionally you catch yourself exclaiming ‘it’s so cute!’ or ‘it’s so huge!’. It was an interesting day as in the morning I measured the largest of the Accipitridae: the cinereaous vulture weighing up to 11.5 kg and with a wingspan of up to 3.1 m. By comparison, I finished the day with the smallest species, the little sparrowhawk which weighs 85 g and has a wingspan of as little as 39 cm! The vulture thus weighs 135 times more and its wingpan is eight times greater. To the vulture, the sparrowhawk would seem a tiny irritating fly! 

It is at this point that we acknowledge that size isn't everything especially when considering the foraging strategy of the vultures compared to sparrowhawks. Both Old World Vultures and the unrelated New World vultures include the largest raptors on earth and yet their diet is largely carrion based. If vultures ever do catch live prey it is generally small in comparison. Behind the vultures in size are eagles from a few genera including Steller’s sea eagle (Haliaeetus pelagicus), martial eagle (Ploemaetus bellicosus), wedge-tailed eagle (Aquila audax), harpy eagle (Harpia harpyja) and Philippine eagle (Pithecophaga jefferyi). Together these apex predators can seize anything from large fish to howler monkeys. 

I highlight the capabilities of large accipitrids to then make the case for the sparrowhawks. Sparrowhawks are famed for their ability to catch relatively large prey. Often garden reports provide photos of sparrowhawks wrestling with woodpigeons or magpies, birds which weigh at least 50% more, if not 3 times as much! That would be like a sea eagle taking a large swan or something even heavier. So you have to give it to these little balls of fury that they know how to hunt!

Week 5: Shearwaters to Herons

Day 17: Manx shearwater - Puffinus puffinus

An old friend

Manx shearwaters are fantastic and I would know because I had the joy of working with them for my undergraduate project. 

In August 2012 I found myself on a small boat departing from mainland Pembrokeshire, destined for the island of Skomer. Skomer, along with neighbouring Skokholm, is home to thousands of seabirds including guillemots, razorbills and puffins. But it is especially important for its huge population of Manx shearwaters. These medium sized tube-noses breed in burrows on a few rocky islands in the British Isles and the North Atlantic. Pairs return from South America every spring to renew their bonds and rear a single chick. Like other procellariiforms, Manxies are superb fliers and as such are not the best on land, as I witnessed first hand. The adults only come to ground under the cover of darkness to avoid beady-eyed gulls who might have them for breakfast.

I went to Skomer at the end of the Summer to coincide with the emergence and fledging of Manxie chicks. Parent shearwaters are so eager to migrate that they depart before the chick is ready and after ten days of weight loss and feeling sorry for themselves, the chicks emerge from their burrows in the dark and begin to stretch their wings. They then fledge after around four days of physical and mental preparation. I was continuing work which involved weighing thousands of fledglings to see if there have been any long-term changes in fledging weight. I confirmed that fledglings of the 2010's were lighter than those of the 1960's and this could have important consequences for their survival.

Manxies were a joy to work with. My assistant and I would roam the islands paths at night, scooping up any chick we came across and weighing them in a plastic cone, The birds showed little fear of humans and could do little to avoid being picked up. It was amusing for us to watch the fledglings ascend rocky outcrops, squabbling as they went, to maximise their fledging chances but despite this they often crashed back to ground or even into us!

It was definitely a formative time in my life, confirming my desire to work in avian ecology. It was also valuable for the things I got to see and do such as caving to find seal pups. Finally I met some really great people that provided me with birding tips, good conversation and plenty of laughs. Manxies now have a place in my heart so that when I now see them shearing past our boat on the south coast I think fondly of my time and imagine that I may even have met one of those birds before.

Day 18: Slavonian grebe - Podiceps auritus

Loch Ness Devil

The Slavonian grebe is a member of the grebe family (Podicipedidae) and order (Podicipediformes). The grebes have much in common with the divers. They are a small order of 22 species across 6 genera ranging from the small-goose-sized great grebe (Podiceps major) to the thrush-sized least grebe (Tachybaptus dominicus). Like the divers, grebes are excellent swimmers using large, lobed feet to chase fish. They are cumbersome on land and fly little yet many species to migrate between southern coastal waters in winter and inland lakes and lochs in the summer. During the breeding season, both sexes sport impressive plumage and the Slavonian grebe is no exception with its golden horns set against thick, black tufts. With its piercing red eyes, the Slavonian grebe earned folk names such as devil-diver, hell-diver and water witch.

Taxonomically, grebes have been difficult to play, traditionally being grouped with the divers on account of their suite of shared characteristics. We now know that these traits were convergently evolved and the grebes are actually sisters of the flamingos within the clade Mirandornithes. Its hard to think of the similarities between these two groups other than their aquatic lifestyle!

The Mirandornithes themselves difficult to position on the bird tree. Taxonomic upheaval resulted this week from a paper in Science describing the relationships of the bird orders from whole-genome phylogenies. In theory this gives us the best estimation of these relationships and analysing whole genomes captures most of the evolutionary change of a species. Many historical relationships were challenged and  with few remaining. Some recently proposed groupings were validated, others thrown out. The grebe-flamingo sistership was supported, the group being named Phoenicopterimorphae. The new phylogeny places the group within the Columbea, which includes pigeons and soundgrouse. In terms of our ordering to date, in light of this new taxonomy, after the Anseriformes we should have moved straight to the grebes and then after the flamingos moved to the pigeons. The divers , tube-noses and penguins would have come later.

Day 19: James' flamingo - Phoenicopterus jamesi

Anyone for croquet?

James' flamingo is typical typical flamingo, tall, elegant and shockingly pink! James' flamingo lives alongside (sympatrically) in the same colonies dotted across the lakes of the Andes. It is one of four New World species in the genus Phoenicopterus (family: Phoenicpteridae; order: Phoenicopteriformes) with another two in the Old World. The pink plumage of flamingos comes from beta carotene, a pigment found in many aquatic algal species which the birds filter from the water using their unusually shaped beaks. A healthy flamingo with a good diet has brighter plumage which is judged when finding a mate.

Flamingos live in huge colonies on lakes around the world. The numbers fascilitate predator swamping whereby the chance of a given individual being attacked by a predator is minimised. Additionally, the patchy distribution of lakes means that flamingos muct cluster together but once on a suitable lake, the superabundance of food can sustain large numbers. The water is often hyper-saline meaning few species are sufficiently adapted to exploit it.

In Alice's Adventures in Wonderland, Alice plays a game of croquet with the Queen of hearts. This event was illustrated in the Disney film where some unsurprisingly flustered flamingos are straightened into long mallets before being swung at hedgehog balls. As a croquet fanatic I am deeply distressed to see the Queen swing the mallets like golf clubs. Clearly the timid King of Hearts did not have the courage to instruct her properly!

Day 20: Little bittern - Ixobrychus minutus

Pint-sized heron

The little bittern is one of the smallest species of heron (Ardeidae) within a genus of miniatures including similarly diminutive dwarf bittern and least bittern. I really enjoyed measuring these birds because they had the same proportions as other herons only scaled down. I imagined one perching on the side of a fish bowl and decided they would make adorable pets.Like other herons, the little bittern has a very long neck relative to its body which it uses to strike at fish and other aquatic prey. For its size, this species occupies a wide range including Europe, Asia and Africa. The rest of the genus cover every continent apart from Antarctica.

The Ardeidae are a group of 63 water birds including herons, egrets and bitters. The Goliath heron is the largest standing at five foot. They share a very similar morphology and ecology with specialisms in size and habitat. They are always a charismatic bird to see and with such an extensive coverage, I can be sure that wherever I am in the world I will never be far from a heron. An old name for herons is shitepokes, apparently for their habit of defecating when flushed.

The Ardeidae are the first family discussed of the Pelecaniformes which also includes the ibises, frigate birds, cormorants, gannets and, of course, pelicans. The new taxonomy places the Pelecaniformes as sister to the Procelariimorphae (penguins and tube-noses).

Week 4: Sea Ducks to Albatrosses

Day 13: Harlequin duck - Histrionicus histrionicus

Commedia dell'arte

The harlequin duck was a stand-out choice for the sea ducks because of its truly splendid plumage. The colours are striking and the pattern distinguished yet it does not have the gaudy accoutrements of other species. The harlequin duck gets its name from the bright, chequered Harlequins of Commedia dell’arte (a sort of early, Italian pantomime). Despite already having a very apt name, it also has a suite of alternative monikers including painted duck, totem pole duck, squeaker and, my personal favourite, blue streak, a description perhaps based on tantalising viewings in the wild.

The sea ducks (Merginae) are a very interesting group of ducks and perhaps the most diverse in shape and sizes. It includes the goldeneye, beautiful, large-headed birds with piercing bright eyes; the eiders, fantastically ornamented ducks, famed for their soft down; scoters, dark sea ducks which form large ocean rafts in winter; and saw-billed ducks, adept at catching fish in their serrated bills. The sea ducks are proficient at catching food below the surface of lagoons and bays and use their large feed to propel them through the water. This can make them very difficult to keep track of as a birder! As with the other ducks, sexes are dissimilar with males often sporting bright or unusual plumage such as the tail feathers of a long-tailed duck or the fleshy bill of a king eider.

This is the last anseriform that I discuss and unfortunately I must bypass the stiff-tailed ducks (Oxyurinae) including the charismatic ruddy duck which now threatens the congeneric white-headed duck via hybridisation. However we will remain on the sea for now.

Day 14: Adélie penguin - Pygoscelis adeliae

Monte the penguin

This is a bird worth talking about on so many levels. Adélies are obviously penguins, one of around 20 species in the penguin order Sphenisciformes. Penguins are very special within the birds having completely abandoned flight in favour of water. We have met birds already, such as ducks and divers, that have moved along the spectrum from air to water. Giving up flight is necessary for this lifestyle because water is a very different fluid from air, requiring different shapes and bone densities. Penguins differ from other aquatic species in their use of their flipper-like wings for propulsion. Since the extinction of the dinosaurs, penguins have specialised in hydrodynamic ‘flight’ through the water in pursuit of fish prey and for this, they cannot take to the air again.

It may come as a surprise that, of the 19 penguin species, the Adélie is one of only four species that live and breed on the Antarctic mainland. Most of the other species inhabit the rocky islands of the Southern Ocean with a few on mainland New Zealand, Australia, South Africa and South America and one species as far north as the Galapagos Islands straddling the Equator. Millions of Adélies cluster into colonies called rookeries around Antarctica in summer to rear clutches of two eggs into tiny chicks.

The behaviour of Adelies was first documented during Captain Scott’s expedition to the South Pole. Tentative groups of penguins were observed to wait on a precipice of ice for the bravest individuals to dive into the sea. Their reverence for potential enemies lurking in the water (such as leopard seals) was not matched by their behaviour towards the dogs and men of the expedition. With no knowledge of the snarling canines they could approach with no fear, merely inquisition. Often this ended in disaster for the unwitting penguin! Among the more unusual observations was ‘the frequency of sexual activity, auto-erotic behaviour, and seemingly aberrant behaviour of young unpaired males and females, including necrophilia, sexual coercion, sexual and physical abuse of chicks and homosexual behaviour.’ This can be ascribed in part to the resemblance of prostrate penguins to enticing females and in part to the lack of knowledge and experience in young males.

This behaviour should be blocked out when watching Monty the penguin waddle at the heels of his doting owner and friend in the John Lewis advert. This advert won the hearts of millions and it certainly came as a surprise to me to see one of my favourite bird species baring my name (near enough anyway). Monty the penguin should be enjoyed as a paragon of love and Christmas spirit and not as a sexually depraved animal attempting to subvert the morals of the British public.

Day 15: Great northern diver - Gavia immer

The bird that created the world

The great northern diver marks a foray into one of the smaller orders, the Gaviiformes. There are only five gaviiform species, all in the genus Gavia and all can be seen in Britain. The great northern, black-throated (Gavia arctica) and red-throated (Gavia stellata) divers spend their winters around the shores of Britain at which time they are grey and dour. In the spring and summer they adopt their striking breeding plumage with the latter two species beginning courtship in lochs and coves in Scotland and the former returning to Iceland and North America. The Pacific (Gavia pacifica) and yellow-billed diver (Gavia adamsii) are only vagrants to the area.

Divers present interesting etymology on three fronts. Firstly, Gavia is actually the Latin for a smew (Mergellus albellus), a small, black-and-white saw-billed duck. This is odd given that the two share less than a passing resemblance with the divers far exceeding the smew in size (among other differences). Secondly, and perhaps less interestingly, the European name diver comes from the very obvious feeding ecology of diving to catch fish. Measuring them, I was impressed at how powerful and blade-like the bill of a great northern diver was. Like the diving ducks, they use their feed to propel them through the water yet their adaptation to this pursuit has greatly diminished their walking ability which brings me to my third point. 

In North America, divers are known as loons which, I thought, was because their eerie cries sound like people short of a few marbles. In actual fact their name derives from either the Old English lumme, which means lummox, or the Scandinavian lum which means clumsy, both of which pertain to their inept walking. I think this is unfair because a diver gliding across the water in breeding plumage is an elegant and beautiful thing.

The wailing call I mentioned has inspired many tales in Native American folklore. According to tribes in British Columbia, rain was predicted from an excess of calls whilst in the Micmac saga a loon named Kwee-moo is a messenger akin to Hermes for the tribal hero Glooscap. For the Ojibwe, a loon actually created the world.

In terms of classification, divers have been difficult to place. For a long time they were thought the most primitive extant birds because of their resemblance to the extinct Hesperornithiformes, an unrelated group which dived for food in a similar manner. Now their placement is anyone’s guess but most favour probably lies with a sistership with penguins, hence their placement on this list.

Day 16: Buller's albatross - Thalassarche bulleri

Foolish gull or ocean chief?

Albatrosses form the family Diomedeidae, the largest of the tubenoses (Procellariiformes), an order so called for their unusual tubular nostrils which they use to smell prey amid the ocean spray. In addition they have enlarged nasal glands used to excrete the excess salt from their diet of fish and seawater. Tubenoses all have similar ecologies differing mainly in their size. They are all true ocean wanderers, usually only returning to land to breed on remote islands. Isolation is needed to protect them from predators as their aerial ability has meant the impairment of walking on land.

Most tubenoses practise natal philopatry, returning to breed at the colonies of their birth. This has probably lead to their genetic isolation from each other despite the fact that they overlap so much when at sea. Whilst foraging, tubenoses can cover vast areas in search of food but they are able to expend little energy doing so, using their supremely aerodynamic wings to fly over the water. Dynamic and slope soaring are techniques which utalise energy from the wind and waves allowing albatrosses to fly up to 1000km a day without flapping their wings!

The Buller’s albatross is a member of the genus Thalassarche, the most numerous of the albatross genera. I could have chosen one of many species within the genus for they are beautiful and noble looking birds with bright, powerful bills and dark frowns. The Thalassarche are commonly called mollymawks, a name deriving from the Dutch Mallemugge which means foolish gull. By contrast Thalassarch means ocean chief. I know which name I prefer.