Munia mayhem

Adult White-headed munia (Lonchura maja maja) Bali

One hotel I stayed at recently in Bali (the Ramada Bintang Bali Resort) had attractive gardens with a number of water fountains. These were a magnet for birds, specifically munias: small, gregarious seed eaters, also called minias or mannikins. One fountain was very much the preserve of White-headed munias (Lonchura maja) which were very abundant.

Water fountain with munias
Water fountain with munias

The White-headed munias flew down to the water fountain where they enjoyed a good bath, splashing and spreading their wings on the water.

White-headed munias (Lonchura maja maja) Bali
White-headed munias (Lonchura maja maja) Bali

There was also one Scaly-breasted munia or spotted munia (Lonchura punctulata) at the fountain (below). There were a few other scaly-breasted munias lurking in the bushes, but this fountain was dominated by the white-headed ones. The juvenile White-headed munias have a more brown, or cinnamon-coloured head.

White-headed munias (Lonchura maja maja) Bali
Scaly-breasted munia or spotted munia (Lonchura punctulata) Bali

There were birds of all ages having a bath. The adults have white heads; the male’s is usually whiter than the female and becomes more bright and extensive as he ages (1). These birds are kept as cage birds in some countries in South-east Asia.

White-headed munias juveniles (Lonchura maja maja) Bali
White-headed munias juveniles (Lonchura maja maja) Bali
White-headed munias (Lonchura maja maja) Bali
White-headed munias (Lonchura maja maja) Bali

After bathing, the birds flew up into the nearby bush, which provided more protection than the exposed fountain.

White-headed munias preening (Lonchura maja maja) Bali
White-headed munias preening (Lonchura maja maja) Bali

Some birds also seemed to be doing a bit of sun-bathing to dry off!

White-headed munias preening and sun-bathing (Lonchura maja maja) Bali
White-headed munias preening and sun-bathing (Lonchura maja maja) Bali

I saw munias all afternoon at the fountain, so either new birds were coming in to bathe (possible) or some were spending quite a lot of time there, moving back and forth between the trees and the fountain.

White-headed munias (Lonchura maja maja) Bali
White-headed munias (Lonchura maja maja) Bali
White-headed munias (Lonchura maja maja) Bali
White-headed munias (Lonchura maja maja) Bali

There was another fountain, rather more shaded and further away from the preening tree, where I came across a pair of White-bellied munias (Lonchura leucogastra) (below).

White-bellied munias (Lonchura leucogastra) Bali
White-bellied munias (Lonchura leucogastra) Bali
White-bellied munias (Lonchura leucogastra) Bali

It turned out that these pair of White-bellied munias were parents; they soon joined the youngsters back under the branches of a near-by tree (below).

White-bellied munia family (Lonchura leucogastra) Bali
White-bellied munia family (Lonchura leucogastra) Bali
White-bellied munia family (Lonchura leucogastra) Bali
White-bellied munia family (Lonchura leucogastra) Bali

The parents (on the right) were busy preening after having had a refreshing bath. It did not look however, like the youngsters had bathed. Perhaps they were still too young and it was too dangerous for them to venture out into the open?

White-bellied munia family (Lonchura leucogastra) Bali
White-bellied munia family (Lonchura leucogastra) Bali

The well-ordered line-up started to disperse and birds swapped places. The fluffy juvenile started to get some attention from one of the adults (below).

White-bellied munia family (Lonchura leucogastra) Bali
White-bellied munia family (Lonchura leucogastra) Bali

It was nice to see all of these birds enjoying the facilities of this hotel! Clearly, these are species which can thrive alongside man, if given a chance and not persecuted.

  1. http://www.finchinfo.com/birds/finches/species/white_headed_munia.php

Such good parents!

Black-legged kittiwake parent and chick on 20th July in Scarborough
Black-legged kittiwake parent and chick on 20th July in Scarborough

Kittiwakes are such good parents! They each spend roughly the same amount of time on the nest looking after the chick(s), whilst the other goes in search of food. During the day, each bird is away from the nest for about 2 hours and 48 minutes (on average) apparently, searching for food to bring back to feed the hungry mouth, or mouths. There may be one or two chicks, occasionally three.

Black-legged kittiwake parent and chick on 20th July, Scarborough harbour
Black-legged kittiwake parent and chick on 20th July, Scarborough harbour

They have a delightful greeting ceremony when one birds returns to the nest and reinforces its bond with the remaining partner. A short while after the greeting, without any ado, they change round and the other bird flies off.

Black-legged kittiwakes (Rissa tridactyla) greeting each other on return to nest
Black-legged kittiwakes (Rissa tridactyla) greeting each other on return to nest
Black-legged kittiwakes (Rissa tridactyla) bonding on return to nest
Black-legged kittiwakes (Rissa tridactyla) bonding on return to nest

The chicks get four or five feeds per day on average (data obtained from the Farne Islands) which provides them with up to 125g of fish per day, although this drops off as they approach fledgling. Despite the hard work of the parents, the chicks seem to beg continuously, even when the parent is dozing!

Black-legged kittiwake chick on 13th July
Black-legged kittiwake chick on 13th July

There is a week between the photographs above and below, of birds nesting in an old, disused electrical junction box by Scarborough harbour.

Black-legged kittiwake chick begging for food
Black-legged kittiwake chick begging for food

The parents are also very dutiful; one parent is almost always present on the nest until the chick is about 33 days old and a reasonable size. In situations like in Scarborough, where there are greedy Herring gulls living cheek by jowl with kittiwakes, the parent needs to protect the growing chick from being predated.

Black-legged kittiwake parent and chick on 20 July, Scarborough harbour
Black-legged kittiwake parent and chick on 20 July, Scarborough harbour

In some sites in Scarborough, including by the lighthouse and on the window sills of the Grand hotel for example, kittiwakes have nests which are very close to where people walk by. They have presumably adapted to the stares and gazes of humans, but the parent birds are occasionally flushed off the nest by a disturbance, but they soon return. Unlike Herring gulls, kittiwake chicks seem better adapted to urban life and don’t seem to fall off their ledges very often!

Kittiwake chick on 20th July
Kittiwake chick on 20th July

We are I think, extremely fortunate to have this beautiful bird living with us in Scarborough. I for one, love their iconic call, and relish witnessing their live cycle every year. The fact that they can survive the rigours of the North Atlantic during the winter (see link 1 to previous blog), yet sit on a ledge above a shop every summer, increases my admiration for this remarkable bird.

  1. https://rcannon992.com/2015/10/26/kittiwake-kittiwake/
  2. Facts and figures taken from: Coulson, John. The kittiwake. A&C Black, 2011.

“Did you hear that?” Said the butterfly.

Blue morpho (Morpho peleides) and Owl butterfly (Caligo atreus)
Blue morpho (Morpho peleides) and Owl butterfly (Caligo atreus)

It used to be thought that butterflies could not hear; that they were deaf. Well I suppose it is understandable, as they do not have ears sticking out from their tiny heads! But it turns out that they can hear – at least some of them can – and they do have ears, but not where you might think. As we shall see, they are on the base of the fore-wings.

It’s long been known that moths (and some butterflies)  have ears which are sensitive to ultrasound – high frequencies above our audible range – and that this trait probably evolved separately numerous times in the family Lepidoptera. Night-flying moths use their high-frequency hearing to detect bats and there is an evolutionary sound war – driven by natural selection – going on between these two nocturnal contestants: predator and prey. The so-called tympanal ears of noctuoid moths, such as the one shown below which I snapped in Thailand, are located on the side of moth (the metathorax) and are said to be tuned to respond to the ultrasonic calls of insectivorous bats.

Asota plana plana (Erebidae). Moths like this have tympanal ears at the junction between the thorax and abdomen.
Asota plana plana (Erebidae). Moths like this have tympanal ears at the junction between the thorax and abdomen.

Butterflies in contrast, evolved into day-flying species, with no need to be able to echo-locate bats like their ancestors did. They have grown bat-deaf! What would be useful for them though, is a way of detecting their daytime predators: birds. It seems that the old bat-detecting ears ears have been adapted to this new purpose in some species like the Blue Morpho butterfly (Morpho peleides).

blue-morpho-morpho-peleides-feeding-on-oranges in a butterfly house
Blue Morpho (Morpho peleides) feeding on oranges in a butterfly house

Ear-like structures have long been noticed at the base of the wings in some nymphalid butterflies. This tiny structure is called Vogel’s Organ. In the Blue Morpho butterfly (shown below) it is an oval-shaped structure composed of inner and outer membranes, which it has been suggested, might allow it to hear two different types of sound frequencies (high and low). It is possible that these butterflies might be ‘listening to the flight sounds of avian predators’ (Lane et al., 2008) and M. peleides may use its two membrane ‘ear’ to ‘detect both singing and flying birds’ (Lucas et al., 2009). It’s not proven yet, but the fact that these butterflies can hear in the range which covers the lower frequency sounds associated with the flapping of bird wings, provides good circumstantial evidence for a putative bird detection system, which can be tested in future experiments (Link 1).

Blue morpho (Morpho peleides) with Vogel's organ at the base of the forewing
Blue morpho (Morpho peleides) with Vogel’s organ at the base of the forewing

The owl butterfly, Caligo eurilochus, also has an ear on the base of its forewings, but according to researchers it is a simpler structure than in the Blue Morpho butterfly. The C. eurilochus ear was most sensitive to sound at frequencies between 1 and 4 kHz, similarly the M. peleides Vogel’s organ is most sensitive to sounds between 2-4 kHz. These could be used to detect the low-frequency components of approaching birds. In other words, they are bird detectors.

Owl butterfly (Caligo atreus) feeding on oranges in a butterfly house
Owl butterfly (Caligo atreus) feeding on oranges in a butterfly house

The owl butterfly is crepuscular, which means that it is most active around dawn and dusk, i.e. during low-light conditions. The ear – or Vogel’s Organ – in C. eurilochus is said to be rather anatomically simple, in comparison to the Blue Morpho.

Owl butterfly (Caligo atreus) - approximate location of Vogel's organ
Owl butterfly (Caligo atreus) – approximate location of Vogel’s organ

We usually know if an animal like a dog or cat can hear us, because it responds in some way to what we say. But it is not easy working out whether something like a butterfly can hear, even if you can find what appears to be its ears.  And when you do work out that they can hear some sounds, it’s not easy to know exactly what they are listening too, and why.

Some butterflies known the ‘crackers’ – Hamadryas spp. – emit surprisingly loud clicks, or ‘clacks’! The clicking or clacking sounds – take your pick – is mostly, but not exclusively, made by males.

Epinome cracker (Hamadryas epinone) from Argentina
Epinome cracker (Hamadryas epinone) from Argentina

A study of the beautiful blue cracker, Hamadryas feronia, in Venezuela, by Jayne Yack (Link 2) and others (2000 paper) at Carleton University (Ottawa, Canada), showed that the males made the ‘sharp clicking sounds’ during chases involving both other males, and females. Typically, a male resting or perching, on the trunk of a tree will take off and fly after another butterfly of the same species as it flies past. If it is another male, they pursue each other, making clicks when they are close to one another. If the male ends up chasing a female, then he ends up conducting what the researchers described as an ‘on-the-wing pendulous display involving continuous clicking’ for the benefit of the female! If she is receptive, then he lands and copulates with her.

Epinome cracker (Hamadryas epinone) puddling
Epinome cracker (Hamadryas epinone) puddling

So it seems that there is a lot more to learn about the sound worlds of butterflies. It is very exciting to think that there may be more complex acoustic interactions going on between butterflies and their avian predators than we ever imagined. So much research has been carried out on the visual markings of butterflies, but it may be that they also rely on sound as well as startling images on their wings to help them avoid the depredations of birds.

All photographs taken by myself either in Argentina or Amsterdam Zoo butterfly house.

Links

  1. http://io9.gizmodo.com/now-we-know-why-butterflies-evolved-to-have-ears-1152166029
  2. https://carleton.ca/biology/people/jayne-yack/

Relevant references

Lucas, K. M., Windmill, J. F., Robert, D., & Yack, J. E. (2009). Auditory mechanics and sensitivity in the tropical butterfly Morpho peleides (Papilionoidea, Nymphalidae). Journal of Experimental Biology, 212(21), 3533-3541.

Lucas, K. M., Mongrain, J. K., Windmill, J. F., Robert, D., & Yack, J. E. (2014). Hearing in the crepuscular owl butterfly (Caligo eurilochus, Nymphalidae). Journal of Comparative Physiology A, 200(10), 891-898.

Conner, W. E., and A. J. Corcoran (2012). Sound Strategies: the 65-million-year-old battle between bats and insects Annual Review of Entomology 57: 21-39.

Ribarič, D., & Gogala, M. (1996). Acoustic behaviour of some butterfly species of the genus Erebia (Lepidoptera: Satyridae). Acta entomologica slovenica, 4(1), 5-12.

Vogel R. 1912. Uber die Chordotonalorgane in der Wurzel der Schmetterlingsflugel. Z Wiss Zool 100:210–244.

Yack, J. E., Otero, L. D., Dawson, J. W., Surlykke, A. & Fullard, J. H. (2000). Sound production and hearing in the blue cracker butterfly Hamadryas feronia (Lepidoptera, Nymphalidae) from Venezuela.Journal of Experimental Biology203(24), 3689-3702.

Yack, J. E. (2004). The structure and function of auditory chordotonal organs in insects. Microscopy research and technique, 63(6), 315-337.

 

 

 

Palawan peacock-pheasant

Palawan peacock-pheasant (Polyplectron napoleonis)
Palawan peacock-pheasant (Polyplectron napoleonis)

The Palawan peacock-pheasant, Polyplectron napoleonis, is endemic to the island of Palawan in the Philippines. I was not sure how easy it would be to see this species during my visit in April, but it proved to be surprising easy.

Palawan peacock-pheasant (Polyplectron napoleonis)
Palawan peacock-pheasant (Polyplectron napoleonis)

The best site to see one is probably at the Puerto Princesa (formerly St Paul’s) Subterranean River National Park on Palawan, Philippines. I came across one within five minutes of getting off the boat!

Puerto Princesa (formerly St Paul’s) Subterranean River National Park on Palawan
Puerto Princesa (formerly St Paul’s) Subterranean River National Park on Palawan

It was very confiding and suggested to me that it was regularly fed, although I could be wrong; certainly it was habituated to humans. Large numbers of people arrive at this site every day to visit the spectacular underground river. A few birders come to see the pheasant (and the underground river!).

Puerto Princesa Subterranean River National Park, waiting for boats
Puerto Princesa Subterranean River National Park, waiting for boats

The Palawan Peacock Pheasant (Polyplecton emphanum) has declined in number due to habitat destruction and hunting, but a thorough survey in the park (1) led to the numbers being revised upwards. The species’s population is now conservatively placed in the band 20,000-49,999 individuals by BirdLife International (2). I would not be surprised if that is an over-estimate though.

Palawan peacock-pheasant (Polyplectron napoleonis)
Palawan peacock-pheasant (Polyplectron napoleonis)

Also hopping around near the back of the generator shed – and looking suspiciously tame – was a hooded pitta. Still, I was very pleased to see it (sorry about the fill-in flash mate!). He/she didn’t seem to mind.

Hooded Pitta (Pitta sordida palawanensis)
Hooded Pitta (Pitta sordida palawanensis)

I also came across a pair of Palawan peacock-pheasants, plus chick, at the Palawan Butterfly Eco-Garden and Tribal Village, in Puerto Princesa City. They said they were keeping it for breeding purposes. Well it seems this pheasant is bred all around the world. Google it and you will find that you can buy one for £380! (3)

Palawan peacock-pheasant (Polyplectron napoleonis) captive PP
Palawan peacock-pheasant (Polyplectron napoleonis) captive PP

The background colour of the tail of the peacock-pheasant is black, but finely speckled with buff spots and with two rows of large and conspicuous green-blue ocelli (or eye-shaped spots). The male displays the spectacular tail to the female in a circular fan during courtship (4, 5).

In peacocks, the mating success of the males was correlated with the brightness and iridescence of the blue-green eyespots (6); the females are in effect choosing the fittest males based on these features. It seems likely, that sexual selection of Palawan peacock pheasant males by the females also involves these spectacular iridescent, light reflective, ocelli or eyespots. Why else would males invest so much energy into them? They are probably a true measure of the fitness of the male birds, as in the case of peacocks.

It makes me wonder what happens in the wild? Are there lek sites where the Palawan peacock pheasant females can evaluate a number of different males? If there are, they are deep in the hot forested hills of Palawan.

  1. Mallari, N. A. D.; Collar, N. J.; Lee, D. C.; McGowan, P. J. K.; Wilkinson, R.; Marsden, S. J. 2011. Population densities of understorey birds across a habitat gradient in Palawan, Philippines: implications for conservation. Oryx 45(2): 234-242.
  2. http://www.birdlife.org/datazone/speciesfactsheet.php?id=281
  3. http://www.allandoopheasantry.com/allandoo_pheasantry_pricelist.html
  4. http://www.arkive.org/palawan-peacock-pheasant/polyplectron-napoleonis/#ref8
  5. http://www.photomazza.com/?Polyplectron-emphanum
  6. Dakin, R., & Montgomerie, R. (2013). Eye for an eyespot: how iridescent plumage ocelli influence peacock mating success. Behavioral Ecology, art045.

Harbour sparrows

House sparrows (Passer domesticus) male and female on lobster pot or creel
House sparrows (Passer domesticus) male and female on lobster pot or creel

Much has been written about the demise of House Sparrows in the UK, which according to the BTO have declined in numbers by nearly 71% since 1977 (1). There are a number of reasons for this decline, including increased pollution, increased predation by resurgent sparrow-hawks and a loss of suitable nesting sites.

House sparrow (Passer domesticus) female on lobster pot
House sparrow (Passer domesticus) female on lobster pot

Crab or lobster pots (creels) provide the perfect solution for seaside sparrows!

House sparrow (Passer domesticus) male on lobster or crab pot
House sparrow (Passer domesticus) male on lobster or crab pot

They can quickly dive into the protected interior of the pots to avoid predation. The pots clearly provide a safe haven for the birds. They dive in and out as people walk past.

House sparrows (Passer domesticus) on lobster pots. Scarborough
House sparrows (Passer domesticus) on lobster pots. Scarborough

I’m not sure if the birds nest inside the pots. I think they probably retire to one of the ivy covered buildings nearby to roost.

House sparrow (Passer domesticus) male on lobster pot, Scarborough
House sparrow (Passer domesticus) male on lobster pot, Scarborough

There are no shortage of creels for the birds to hide in. As long as they don’t linger and get taken out to sea as crab bait!

Crab pots or creels, Scarborough harbour
Crab pots or creels, Scarborough harbour

The sparrows certainly seem to like these creel pots because they are always to be found there. Whether birds in other, non-coastal sites, would benefit from a few lobster pots being placed for their protection, I cannot say. But perhaps it is an idea worth considering?

  1. http://www.bto.org/volunteer-surveys/gbw/about/background/projects/sparrows

The amazing Purple Sandpiper!

Purple sandpiper (Calidris maritima), Scarborough on 20 Dec 2015
Purple sandpiper (Calidris maritima), Scarborough on 20 Dec 2015

A small flock of Purple Sandpipers overwinter in Scarborough, North Yorkshire, every year. It is very easy to see these beautiful birds roosting just above the water on the artificial concrete sea defences on the East Pier of Scarborough Harbour. They fly off to feed on nearby locations were they feed on a variety of marine invertebrates. The nice thing about Purple Sandpipers is that there are very confiding; meaning that they don’t much mind people looking at them! Numbers seen in Scarborough harbour vary, but as many as 77 birds were seen on 24th Dec 2015 (1).

Purple sandpipers (Calidris maritima) 20 Dec 2015
Purple sandpipers (Calidris maritima) 20 Dec 2015

Apparently, there are long and short-billed populations of Purple Sandpipers. There are long-billed birds which come over from Canada or east Greenland, and are found predominately in the north and west of the British Isles (3). The short-billed population found along the east coast of Britain (Scotland and England) – so presumably the birds we see in Scarborough – is said to originate from Norway. These birds have both shorter bills and shorter wings than their Canadian cousins, and comprise about a quarter of the British population (4); said to number about 21,000 birds (3). It seems that some of the birds seen on the eastern coasts of Britain return to breed in the beautiful mountain plateau, known as Hardangervidda, in central southern Norway (3). It would be nice to go there to see these birds in their attractive breeding plumage. A tiny number of birds have bred in Scotland (4) but this does not occur every year according to the BTO (6) and the location is a closely guarded secret to protect them.

Purple sandpiper (Calidris maritima) 23 Dec 2015
Purple sandpiper (Calidris maritima) 23 Dec 2015

Purple Sandpipers overwintering in northern Scotland and southwest Ireland were fitted with tiny (1.4g) geolocators, which established that they were breeding in northern Canada (Baffin Island and Devon Island) (4). Incredible as it may seem, this study showed that the birds flew from Baffin Island to Scotland and Ireland in about 2.5 days, travelling about 1,400 km per day. To achieve that they would have had to average over 36 mph, day and night! It is also not clear why some long-billed Purple Sandpipers from Canada fly all the way to Scotland and Ireland, when others from the same breeding location only fly as far as south-west Greenland and Iceland (4). Some, like those breeding in Iceland, are said to be completely resident (3).

Purple sandpiper (Calidris maritima) 20 Dec 2015
Purple sandpiper (Calidris maritima) 20 Dec 2015

So amazingly, the Purple Sandpipers we see around the British Isles are a mixed bunch, though you would have to be a pretty skilled birder to differentiate them, and I have not seen a handbook which attempts to describe the short- and long-billed forms, so the difference must be very subtle. The bills vary in length by about 4 mm between the short- and long-billed populations (3), although the average lengths differ according to region (Iceland, Canada, Norway, Russia and so on). Still, it’s nice that these different populations have chosen to come to the British Isles to spend their winters!

Purple sandpiper (Calidris maritima) 23 Dec 2015
Purple sandpiper (Calidris maritima) 23 Dec 2015

 

Female Purple Sandpipers are larger than the males, although I have not found it easy to separate them in a flock!

Purple sandpiper (Calidris maritima) flock
Purple sandpiper (Calidris maritima) flock
  1. http://www.scarboroughbirding.co.uk/
  2. http://jncc.defra.gov.uk/pdf/UKSPA/UKSPA-A6-66.pdf
  3. Wernham, Chris. “{The Migration Atlas: Movements of the Birds of Britain and Ireland}.” (2002).
  4. http://www.birdwatchireland.ie/LinkClick.aspx?fileticket=LFPY0CTxO1E%3D&tabid=1486
  5. https://britishbirds.co.uk/wp-content/uploads/article_files/V76/V76_N12/V76_N12_P563_565_A146.pdf
  6. http://www.bto.org/about-birds/bird-of-month/purple-sandpiper

Peck me here! Butterfly predation.

Fluffy Tit (Zeltus amasa amasa) worn and damaged
Fluffy Tit (Zeltus amasa amasa) worn and damaged

It is said that  50% of wild butterflies are killed and eaten before they get a chance to mate and reproduce (1). Poor things! One way to avoid being eaten is to divert the lethal pecks of predatory birds towards body parts that can be sacrificed in the interests of survival. Obtaining direct evidence for the protective utility of eyespots is difficult, but the deflective function of marginal eyespots has been demonstrated in some studies. It has also been shown to work well under low light conditions – such as at dawn and dusk – when birds are most active (2).

Photographs of butterflies often show evidence of extensive damage. Whilst such evidence of ‘beak marks’ – damage caused by a would be predator – is only circumstantial, it is a good indication of the fact that it is a regular occurrence in nature. Indeed, photographs could perhaps be used as a research tool into the intensity of such attacks, although one would only observe the survivors! The others would be inside the birds stomachs. Once pecked, as in the above photograph, the eyespot may be lost, so the butterfly is presumably more vulnerable to subsequent attacks. It has also been shown that eyespots can function in different ways in different seasons: eyespot plasticity! In the dry season, eyespots are a liability, so natural selection has resulted in the evolution of a spotless form – able to blend in well against brown, dead leaf litter – and another form, with eyespots, in the wet season, where they have an evolutionary useful deflective function (3).

Another feature which has become obvious to me as I have taken more and more photographs of butterflies, is that they are seemingly able to fly about and carry out their lives, despite sustaining considerable damage to their wings. Some of this may be simple ‘wear and tear’ as well as predation damage. I have written about this before (4)! It’s a subject which fascinates me for some reason! Perhaps its something to do with our universal fragility? Compare these two images, below. The first, a highly worn and presumably ‘old’ butterfly – a male Clipper, Parthenos sylvia apicalis. The second, a much fresher specimen of the same species – but nevertheless, still sporting a beak mark on the left hind wing – which only became apparent to me after I photographed it and looked at the image on my computer. Yet both individual butterflies were gaily flying around and resting to feed on flowers. Indistinguishable to the casual observer. For some reason, perhaps to do with age, I take comfort in this fact!

Clipper Parthenos sylvia apicalis male, highly worn and damaged
Clipper Parthenos sylvia apicalis male, highly worn and damaged
Clipper (Parthenos sylvia apicalis) male, with small beak mark
Clipper (Parthenos sylvia apicalis) male, with small beak mark

All three images were taken in Doi Chiang Dao, in northern Thailand.

  1. http://www.learnaboutbutterflies.com/Enemies%20of%20Butterflies.htm
  2. Olofsson, Martin, et al. “Marginal eyespots on butterfly wings deflect bird attacks under low light intensities with UV wavelengths.” PLoS One 5.5 (2010): e10798-e10798.
  3. Lyytinen, Anne, et al. “Does predation maintain eyespot plasticity in Bicyclus anynana?.” Proceedings of the Royal Society of London B: Biological Sciences 271.1536 (2004): 279-283.
  4. 4. https://rcannon992.com/2013/12/15/predation-on-butterflies/

Little beggars!

Turnstones with rings, Scarborough, 7th Nov 2015
Turnstones with leg rings, Scarborough, 7th Nov 2015

Turnstones (Arenaria interpres) are a common sight all around the harbour, during the winter, in Scarborough. Many of them have been fitted with coloured leg rings and flags (PVC) which is part of an ornithological study to investigate where they migrate to in the summer. Turnstones which have been ringed in Great Britain & Ireland have been recovered, i.e. found and released again, in Greenland, Iceland, Scandinavia and all the way down the coasts of western Europe and West Africa (1).

Turnstones waiting for scraps, Scarborough
Turnstones waiting for scraps, Scarborough

Anyway, the ones that live in Scarborough during the winter are quite tame, and like to hang around the car parks near the pier waiting for people to throw scraps – the remains of their pasties or fish and chip lunches! – out of the car window. When a car door opens, they rush over to see if anything edible is being tossed out! It often is. In the meantime, they were waiting in a space, enjoying the winter sun. I liked the way they cast a shadow in the afternoon light.

Turnstones with shadows, Scarborough
Turnstones with shadows, Scarborough

Quite a few of them had rings and flags. They carry these little coloured markers with them on their journeys across the world. According to the British Trust for Ornithology, a bird with a coloured ring is a bit like wearing a watch is for us! (2) A bit like wearing a Swatch watch I expect! Well maybe, but bird rings are not totally without effects. Some studies have demonstrated problems caused by plastic rings (3). They are however, mostly benign and generate a lot of useful information which benefits the species in terms of conservation and knowledge. So these little beggars will have to keep wearing their coloured watches for a while yet!

Turnstones with shadows, Scarborough
Turnstones with shadows, Scarborough
  1. http://blx1.bto.org/ring/countyrec/resultsall/rec5610all.htm
  2. http://www.bto.org/volunteer-surveys/ringing/about/faqs
  3. Griesser, Michael, et al. “Causes of ring-related leg injuries in birds–evidence and recommendations from four field studies.” PloS one 7.12 (2012): e51891.

Kittiwake kittiwake!

Black-legged kittiwake (Rissa tridactyla), Scarborough
Black-legged kittiwake (Rissa tridactyla), Scarborough

The cliffs along Marine Drive, Scarborough, are bare and strangely quiet now that winter is coming. The kittiwakes have long since left and are far away, over the ocean. Only a pair of lonely peregrine falcons keep watch on the cliffs now, waiting patiently for their sandeel-packed lunches to return in the new year!

Kittiwakes on Castle Cliff, Scarborough (24-07-15)
Kittiwakes on Castle Headland cliffs, Scarborough (24-07-15)

According to a report prepared for Scarborough Borough Council, the kittiwakes first began nesting on Castle Headland in 1940; by 1959 the colony had increased to about 360 pairs and currently exceeds 1,500 pairs. This is in line with increases of about 3% per year in kittiwake populations – and the formation of many new colonies  – for much of the 20th Century (2). It is reassuring to learn that the kittiwake population in Scarborough is reportedly stable, unlike some other areas in the UK (see below).

Kittiwakes nesting on Castle Headland cliffs, Scarborough
Kittiwakes nesting on Castle Headland cliffs, Scarborough

At the end of the breeding season, the Black-legged kittiwakes (Rissa tridactyla) – to give them their full scientific name – leave their nesting sites and disperse widely, spending most of the winter in northern oceans ‘far from land and most humans’ according to John C. Coulson (2011) in a book called The Kittiwake (2). Until recently, our knowledge of where kittiwakes went during the winter was somewhat limited. Direct observations from ships revealed that they spread out across the whole North Atlantic during winter, reaching as far south as 30-35 degrees north (7). Once in the Atlantic ocean, they appear to be ‘nomadic’, in that their movements and locations are strongly influenced by weather conditions (7). Kittiwake movements along the coasts of Britain and Ireland in winter, have shown that they move away from Atlantic depressions and strong winds, flying perhaps as far as 1,000 km in a single day (2). According to Coulson, these ‘movements make their oceanic distribution fluid and variable’ (2). What clever birds they are!

Black-legged kittiwake (Rissa tridactyla), Scarborough
Black-legged kittiwake (Rissa tridactyla), Scarborough

Recently, technological advances in miniaturization have enabled researchers to attach geolocation devices to smaller birds such as kittiwakes, so that they can now be tracked through the winter. A total of 80 breeding kittiwakes were fitted with tiny (1.5 g) geolocation loggers – which amount to about 0.4% of the body weight – to a leg ring (1).  During the period between leaving the vicinity of the colony in late summer and returning the following spring, the birds dispersed to both sides of the Atlantic Ocean, as well as the North Sea. The routes taken by some birds are shown in the following diagram (Figure. 2 from Bogdanova et al., 2011). It’s amazing to think that the birds I watched nesting on a ledge above the entrance to a shop in Scarborough this summer, will be making similar such epic journeys this winter! What intrepid globetrotters they are.

Routes taken during pre-breeding trips by 10 kittiwakes from a colony on Isle of May National Nature Reserve, southeast Scotland (Bogdanova, M. et al., 2011)
Routes taken during pre-breeding trips by 10 kittiwakes from a colony on Isle of May National Nature Reserve, southeast Scotland (Bogdanova, M. et al., 2011)

Black-legged Kittiwakes usually lay two eggs (with one to three also occurring) in the Spring, around May (late April to early June)(2). After hatching, one parent always remains on the nest to brood the chick, whilst the other one goes off to look for food.

Black-legged kittiwake chicks with one parent bird, Scarborough harbour, 15-07-2015
Black-legged kittiwake chicks with one parent bird, Scarborough harbour, 15-07-2015

The chicks are not left by themselves until they have grown to a good size, perhaps after 33-40 days (2). The parents leave their nests for about 2 hours and 48 minutes on average, which Coulson calculates gives them a potential feeding range of 63 km (40 miles) if they fly at 45 km per hour (2). Although, they are going to need time to feed, and perhaps ever take a rest!

Two Black-legged kittiwake chicks by themselves, Scarborough harbour, on 15-07-2015
Two Black-legged kittiwake chicks by themselves, Scarborough harbour, on 15-07-2015

Another study, of kittiwakes breeding on the on the Isle of May in Scotland, found that during the breeding season the adults forage up to about 73 ± 9 km from the colony (3). During these trips the birds are looking for and feeding on a small pelagic fish: predominantly the lesser sandeel (Ammodytes marinus). Their remarkable tongue, must be an adaptation for feeding and catching such prey items on the surface of the sea.

Black-legged kittiwake (Rissa tridactyla) showing tongue
Black-legged kittiwake (Rissa tridactyla) showing tongue

In Scarborough, North Yorkshire, kittiwakes nest on suitable ledges all over the town, especially on old or abandoned buildings. Apparently, they only started doing this in 1994. They make quite a mess and some owners erect nets to prevent the birds from returning the following season. When this happens, and the birds arrive and cannot access their former nesting ledges, they stand around for a few weeks, before moving onto other suitable ledges or cliffs (8). I can imagine them silently muttering to themselves, who blocked off our nesting site! I shall have to watch what happens when the birds that used to nest over the entrance to M&S this year (2015), return next year and find their site covered by mesh! The birds nesting in town generally do not seem to be much bothered by the presence of people on the roads and pavements below them. I think most people like to see these birds, although some do not realise that they are very different from Herring gulls. They are all just grouped together as seagulls. Personally, I love the cry of the kittiwake!

Kittiwakes nesting on widow ledge near the harbour, Scarborough
Kittiwakes nesting on widow ledge near the harbour, Scarborough

Once the young kittiwakes have fledged and left the parental colony, they no longer receive any parental care. They only receive food from their parents at the nest site. The chicks spend about ten days around the colony after they have made their first flight (2). One morning in late July, I noticed many fledglings sitting on the breakwater on Marine Drive (below the breeding cliffs) or sitting on the water. At this stage they could presumably still return to their breeding ledge to receive a free meal from one of their parents.

Newly fledged kittiwake chick resting on Marine Drive, Scarborough, on 24-07-2015
Newly fledged kittiwake chick resting on Marine Drive, Scarborough, on 24-07-2015

It is remarkable to think that these young birds will soon be flying off, by themselves, for thousands of miles; many going as far as the other side of the Atlantic (wintering off Newfoundland and Greenland) (7). Once they leave the colony, the bond with their parents is abruptly broken, and they have to forage for themselves (2). Many of them will not return ‘home’ for a few years, and even then they will not begin to breed themselves, until they are at least three years old, possibly not until they are six (2, 7).

Newly fledged kittiwake chick below Castle Headland, Scarborough, on 24-07-2015
Newly-fledged kittiwake chick below Castle Headland, Scarborough, on 24-07-2015

So once they are ready to go, it is important that they find good feeding sites. Some fly as far as 4,000 km in six weeks after leaving, probably travelling with other more experienced birds and learning from them (2). After all, it cannot all be innate! Some kittiwakes have lived for over 28 years (2) and these individuals must have accumulated a great deal of experience (wisdom) during their journeys back and forth across the Atlantic. Where to find food at sea; how to avoid dangerous storms; and so on. The younger birds can learn from their elders!

Black-legged kittiwake (Rissa tridactyla)
Black-legged kittiwake (Rissa tridactyla)

In the North Sea, kittiwakes feed on planktonic crustacea in the early spring, then switch to larger sandeels in April and May, and later on, switch to feeding on the shoals of small, newly hatched, larval sandeels, which occur near the surface in June and July (6).  There have however, been declines in kittiwake populations, perhaps in association with sandeel fisheries, as well as with increases in late winter sea surface temperature (4, 5). According to Coulson, it is not clear ‘whether these fluctuations in sandeel abundance are natural or caused by intensive fishing’ (2). But many people would agree that it would be a sensible precaution to maintain a ban on sandeel fishing to protect kittiwakes.

Newly-fledged kittiwake chick on Marine Drive, Scarborough, 24-07-2015
Newly-fledged kittiwake chick on Marine Drive, Scarborough, 24-07-2015

Coulson also downplays the effects of climate change, writing: ‘it is difficult (for me) to believe that these [changes in average sea surface temperatures of about 1 deg C in the past 30 years] have already appreciably influenced the kittiwake throughout its whole range’ (2). That may be the case, since the kittiwake has such a broad distribution, but locally there have been steep declines: for example an 87% decline in kittiwakes on Orkney and Shetland since 2000, according to the RSPB (9). The RSPB are unequivocal in putting the blame on climate change for these massive declines in Scotland’s seabird populations (9). If this is the case, there is probably not much we can at this stage, to reverse the predicted rise in ocean temperatures – perhaps as much as 2-3 deg C – in the near future. So the kittiwakes are going to have to try to adapt, as best they can, to this uncertain future. The kittiwake does have an extremely large range – in both the North Pacific and the North Atlantic – and a very large global population, estimated to be between 17-18 million pairs, according to BirdLife International (10). According to this website, the decline in the global kittiwake population is not believed to be sufficiently rapid to approach the threshold for being classed as Vulnerable (i.e. a >30% decline over ten years or three generations). It is to be hoped that if climate change does impact the food availability for kittiwakes in some areas, there are enough colonies in areas where there are alternative prey species which may be available to them. We can only hope so, and it makes one realise how lucky we are to have this beautiful bird nesting on our doorstep, and sometimes literally on our windowsills (!), here in Scarborough. Long may it prosper.

Adult Black-legged kittiwake (Rissa tridactyla), Scarbourgh harbour
Adult Black-legged kittiwake (Rissa tridactyla), Scarbourgh harbour

References

  1. Bogdanova, Maria I., et al. “Seasonal interactions in the black-legged kittiwake, Rissa tridactyla: links between breeding performance and winter distribution.”Proceedings of the Royal Society of London B: Biological Sciences (2011): rspb20102601.
  2. Coulson, John. The kittiwake. A&C Black, 2011.
  3. Daunt, Francis, et al. “Foraging strategies of the black-legged kittiwake Rissa tridactyla at a North Sea colony: evidence for a maximum foraging range.”Marine Ecology Progress Series 245 (2002): 239-247.
  4. Frederiksen, Morten, et al. “The role of industrial fisheries and oceanographic change in the decline of North Sea black‐legged kittiwakes.” Journal of Applied Ecology 41.6 (2004): 1129-1139.
  5. Frederiksen, Morten, et al. “Regional and annual variation in black-legged kittiwake breeding productivity is related to sea surface temperature.” MARINE ECOLOGY-PROGRESS SERIES- 350 (2007): 137.
  6. Lewis, Sue, et al. “Diet and breeding performance of black-legged kittiwakes Rissa tridactyla at a North Sea colony.” Marine Ecology Progress Series 221 (2001): 277-284.
  7. Wernham, C. V., et al. “The Migration Atlas: Movements of the Birds of Britain and Ireland (T. & AD Poyser, London).” (2002).
  8. http://democracy.scarborough.gov.uk/documents/s63134/SCR1502%20GULLS%20FINAL%20REPORT%2020150309.pdf
  9. http://www.rspb.org.uk/news/details.aspx?id=366903
  10. http://www.birdlife.org/datazone/speciesfactsheet.php?id=3255

Heron Food II

Heron with fish
Heron with fish

Retirement is having enough time to sit and watch herons feeding! I watched this Grey heron (Ardea cinerea) feeding in a rock pool, at low tide, at Scalby Mills, which is located at the north end of North Bay, Scarborough, North Yorkshire. It had just discovered and picked up a fish – maybe a grey gurnard? It then spent about ten minutes trying to swallow it.

Heron with fish
Heron with fish

First of all it tried to align it length-ways – head first along the beak – and had a first attempt at swallowing it. For some reason this did not work, so it gripped the fish by its head and placed in down on the seaweed.

Heron with fish
Heron with fish

Placing the fish on the seaweed (below). It then picked it up very quickly, and performed this operation of trying to swallow it, followed by putting it down again, about three times.

Heron with fish
Heron with fish

It did not wait long before picking it up again each time (below).

Heron looking at the fish on the seaweed
Heron looking at the fish on the seaweed

The heron almost seemed to be saying to itself “I can swallow this, I can!”

Heron with fish
Heron with fish

Eventually, it picked up the fish for the last time – was it waiting for it to die and stop moving? – and aligned it headfirst. But once again it moved the fish about until it was content to have a go at swallowing it. Was this fish approaching the upper size limit for prey items?

Heron grappling with a fish
Heron grappling with a fish

Eventually, the heron swallowed the fish. It did this quite quickly and I only just managed to get the money shot of the fish going down!

Heron swallowing fish
Heron swallowing fish

The heron then stood up and I imagined it gulping the fish down into its stomach.

Heron, seconds after swallowing a large fish
Heron, seconds after swallowing a large fish

When I look at herons now, I will always have the unsavory thought of what hapless creature – fish, duckling, crab etc. – has just disappeared down into its belly!