Sperm whales

Sperm whale (Physeter macrocephalus) tail fluke
Sperm whale (Physeter macrocephalus) tail fluke

There are thought to be about 200,000 sperm whales in the world, but there is considerable uncertainty about the figure, which may be anywhere between  200,000-1,500,000 according to one site (1). The IUCN Red List states that the pre-whaling global population of sperm whales was about 1,100,000, so the number is probably much lower than that, in the hundred’s of thousands (2). It is surprising to me that there are no reliable estimates for this iconic animal. Perhaps it shows how little we still know about our oceans.

I had the good fortune to come across a few of these creatures on a voyage between Bali and Komodo (Indonesia) in October, 2016, on board a little ship called Mermaid I (3).

Mermaid I at anchor
Mermaid I at anchor

There are some phenomenal images of sperm whales on the Internet; just google it and you will see fantastic underwater photographs of these huge whales floating majestically below the surface. They are relatively shy creatures, so how divers get so close I don’t know, perhaps they are less wary of humans in the water, than of ships. Sperm whales live for up to 70 years, perhaps more, and sperm whaling was being carried out by Japan until 1988, so many of them may remember being perused and seeing their companions slaughtered. The Japanese are still killing Antarctic minke whales (4).

The first thing you see, as ever child knows, is the blow or outbreath. The Sperm Whale’s blow-hole is set at an angle on the left-hand side of its head; which causes the blow to shoot to the left (below).

Sperm whale blowing to the left
Sperm whale blowing to the left

It is very exciting when you come across a whale! The first one we saw was on the way to Satonda Island, north of the large island of Surabaya. Our small ship approached slowly so as not the frighten the whale, and we managed to get relatively close, although I was using a long lens (150-600mm).

Sperm whale I (Physeter macrocephalus) on the surface
Sperm whale (Physeter macrocephalus) on the surface

Before we could get much closer however, the whale ‘turned tail’ and started to dive. The average dive apparently lasts for about 35 minutes and is usually ‘only’ down to about 400 m, although they can stay down for an hour or so and reach depths over 1,000 m (1). I guess it depends on what they find down there and whether they start chasing some prey item. Or perhaps they get into protracted fights with giant squids who do not relish being consumed by this giant predator of the depths!

Sperm whale I (Physeter macrocephalus) diving
Sperm whale (Physeter macrocephalus) diving

After this whale had disappeared beneath the waves, we realised that there was a small one still at the surface: probably a calf. Females have a calf about once every five years and they stay together for several years. Perhaps this one was too young to start deep diving? Although it has to learn at some stage, and presumably gets lessons from the mother?

Sperm whale (Physeter macrocephalus) calf at the surface
Sperm whale (Physeter macrocephalus) calf at the surface

The next sperm whale we came across was in the open ocean south of the Komodo national park waters. Once again there was the tell-tail blow in the distance. Once again the ship slowed and approached the whale gradually, hoping it would not get spooked and dive down before we could see it.

Sperm whale (Physeter macrocephalus) blowing at surface
Sperm whale (Physeter macrocephalus) blowing at surface
Sperm whale (Physeter macrocephalus) at surface
Sperm whale (Physeter macrocephalus) at surface

This whale was a little bit more co-operative and we managed to get slightly nearer than the first one, but it too soon decided that enough was enough, and it dived down. Being behind it this time, we got a better view of the great tail fluke as it turned and dove in its majestic swoop.

Sperm whale (Physeter macrocephalus) diving
Sperm whale (Physeter macrocephalus) diving
Sperm whale (Physeter macrocephalus)
Sperm whale (Physeter macrocephalus)
Sperm whale (Physeter macrocephalus) tail fluke
Sperm whale (Physeter macrocephalus) tail fluke

I would like to have got better photos, but one gets what one is given, and I am grateful to have seen it. The last image is of the big flukes disappearing beneath the waves.

Sperm whale (Physeter macrocephalus)
Sperm whale (Physeter macrocephalus)

You don’t have to go all the way to Indonesia to see Sperm whales, they have a global distribution and are found around the shores of the United Kingdom. Indeed, there have been a number of high-profile stranding in recent years. Six sperm whales beached in Norfolk and Lincolnshire in 2016 (5). And a total of 29 stranding on the shores of the North sea as a whole in 2016.

Whilst there are records of these whales stranding as far back as 1577 (6), the fact that some of them have been found to have empty stomachs is very worrying. Especially, as the ones that beached in Germany, in Schleswig-Holstein, had stomachs which were filled with plastic debris (including discarded fishing nets) (7). Alas, we humans are fouling up this planet and the seas are filling up with plastic. It’s truly shocking. Unfortunately, it takes something like a dead sperm whale with a stomach full of plastic (or a dead albatross) to ram home the message that we are polluting the planet with our debris.

Plastic pollution
Plastic pollution
  1. http://www.fisheries.noaa.gov/pr/species/mammals/whales/sperm-whale.html
  2. http://www.iucnredlist.org/details/41755/0
  3. https://rcannon993.wordpress.com/2017/01/17/travelling-with-a-mermaid/
  4. https://en.wikipedia.org/wiki/Whaling_in_Japan
  5. http://www.bbc.co.uk/news/uk-england-norfolk-35491621
  6. http://www.seawatchfoundation.org.uk/the-sad-spate-of-sperm-whale-
  7. https://www.theguardian.com/commentisfree/2016/mar/30/plastic-debris-killing-sperm-whales

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

Lizard language

Javanese Flying Lizard (Draco volans) gular flap extended
Javanese Flying Lizard (Draco volans) gular flap extended

Flying lizards are a common group of agamids in southeast Asia. The Common Gliding Lizard, Draco Volans – also called the Javanese flying lizard – is found in Java and Bali (1). These photographs were taken in Bali Barat NP, so perhaps they should be called the Balinese flying lizard. The males have a very obvious, pointed yellow gular flag, which they constantly flick up and down to signal to other members of their species.

Javanese Flying Lizard (Draco volans) gular flap deflated
Javanese Flying Lizard (Draco volans) gular flap deflated

Spend a few minutes watching these lizards and they reveal a variety of different behaviours, including: push-ups (head bobbing), flattening themselves against the trunk of the tree, extending their peculiar throat (or gular) flap, raising their tail and so on. They are incredible fast-moving and energetic when they want to be and I got the impression that there was a constant buzz of activity going on, with males chasing females and challenging other males for territory. What is really incredible is when they launch themselves into the air and fly – gliding really – from tree to tree. It is quite startling if you have never seen it before. I couldn’t believe how adept they were at gliding through the forest. Unfortunately I did not manage to get a photograph of them flying. They are able to glide considerable distances, say 30m or so, by extending the expanding the loose skin – called the patagium – on the sides of the body. This ‘wing’ is usually folded away and can only be guessed at by the tightly folded skin on the sides of their body (below).

Javanese Flying Lizard (Draco volans) showing folded skin on sides of body
Javanese Flying Lizard (Draco volans) showing folded skin on sides of body

Lizards of many different species perform push-up movements and head-bobbing. Three different types of push-ups were recorded for the Sumatran subspecies, Draco volans sumatranus! (2) Quite what all these signals mean is only fully known to the lizards themselves, but probably has to do with communicating the attributes, size, status and so on, of the lizard carrying out the display. Some movements, like the so-called, dorsal flattening, is carried out when birds fly past overhead, and simply serves to improve the already excellent camouflage (see below).

Javanese Flying Lizard (Draco volans) Bali showing well-camouflaged dorsal view
Javanese Flying Lizard (Draco volans) Bali showing well-camouflaged dorsal view

They are said to mostly feed on ants, so serve a very useful ecological function.

Javanese Flying Lizard (Draco volans) Bali. Female eyeing ants
Javanese Flying Lizard (Draco volans) Bali. Female eyeing ants

The females have a small, mottled, bluish gular flag but I did not witness one waving it! All that can be seen on the females in these photographs is a blueish throat. Females of some species of lizard raise their tails in response to encountering a male (3); so perhaps this one (below) was doing just that?

Javanese Flying Lizard (Draco volans), female in profile with tail raised.
Javanese Flying Lizard (Draco volans), female in profile with tail raised.

It would be fascinating to watch and study the behaviour of these lizards in more detail. There is a repertoire of behaviours going on; I am sure that there is much to be discovered.

  1. http://ecologyasia.com/verts/lizards/common_gliding_lizard.htm
  2. Mori, A., & Hikida, T. (1994). Field observations on the social behavior of the flying lizard, Draco volans sumatranus, in Borneo. Copeia, 124-130.
  3. Radder, R. S., Saidapur, S. K., Shine, R., & Shanbhag, B. A. (2006). The language of lizards: interpreting the function of visual displays of the Indian rock lizard, Psammophilus dorsalis (Agamidae). Journal of ethology, 24(3), 275-283.

Tigers mating

There is however, no guarantee that the female will be receptive. Females might reject males for a number of reasons; he just might not look right (being a different subspecies perhaps); he might be too small (she may be seeking a large spermatophore produced by a large male); he might not smell right (the sex pheromones and volatile cuticular hydrocarbons); or she may have already mated (1). Bad luck! She indicates her refusal by bending her abdomen in a certain way and flapping her wings.

Source: Tigers mating

Tigers mating

Danaus chrysippus bataviana male and female in copulation
Danaus chrysippus bataviana male and female in copulation

The Plain Tiger, Danaus chrysippus (Linnaeus, 1758), is a butterfly with an enormous distribution – from West Africa to New Zealand (1, 2). There are a large number of different forms or subspecies comprising what is called a ‘species complex’. This is a name given to a group of insects by taxonomists when they don’t really know, or disagree, as to whether the different forms are genuine species, or subspecies, or semi-species, or just a confusing plethora of hybridizing populations evolving before our eyes!

Danaus chrysippus bataviana male nectaring
Danaus chrysippus bataviana male nectaring

Evidence of the variation in this ‘species complex’ is reflected in the variety of common names for this butterfly: Plain Tiger, Common Tiger, African Monarch, Lesser Wanderer, African Queen and so on. There is an even longer list of synonyms, that is to say, alternative scientific names that have been used, superseded or revised down the centuries.

Danaus chrysippus bataviana male showing ups right wing pattern clearly
Danaus chrysippus bataviana male showing ups right wing pattern clearly

To get round the problem of trying to come up with a name for an entity which includes a number of different forms or subspecies, biologists use the term sensu lato, meaning ‘in the broad sense’. Hence Danaus chrysippus sensu lato (s.l.) is the term used to describe all of the different forms, subspecies, or what have you, of this polytypic butterfly, which occur throughout most of the Afrotropical, Oriental and Australian Regions. There are of course definitive biological features which distinguish the butterflies within this D. chrysippus complex, i.e. from all other Danaus species. These include the presence of certain white scales and black spots on the hind-wings (1).

Danaus chrysippus bataviana male nectaring
Danaus chrysippus bataviana male nectaring

The Oriental form of the Plain Tiger, Danaus chrysippus chrysippus Linnaeus, 1758 – has perhaps the widest distribution, from Morocco all the way across the Old World to southern Japan. The life history of this butterfly has been comprehensively described and illustrated on the excellent, Butterflies of Singapore, website (3). There are also a large number of photographs of this subspecies on the Butterflies of India website (4).

Danaus chrysippus bataviana male nectaring
Danaus chrysippus bataviana male nectaring

The subspecies shown here, Danaus chrysippus bataviana, has a much more limited distribution and occurs only on Java, Sulawesi (part) and the Lesser Sunda Islands, which include Bali, all in Indonesia. These photographs were taken on Bali. The upper hind wings of this subspecies appear to be darker (described as brown by one authority) than those of D. c. chrysippus (5). There are also reports of this subspecies occurring in Malaysia, together with D. c. chrysippus, in isolated but sometimes dense colonies (6), which makes me wonder just how geographically distinct these different subspecies are. Indeed, Smith (2014) states that: ‘D. c. bataviana and D. c. chrysippus are distinct subspecies separated by a narrow, dynamic hybrid zone which has, and may still be, on the move’. It would be interesting to know whether anyone has studied this butterfly across these regions?

Danaus chrysippus bataviana male showing upper (dorsal) side on wings
Danaus chrysippus bataviana male showing upper (dorsal) side on wings

It is fairly easy to tell the sexes apart in these species. The males have a large black spot on the hind-wings which the females lack. On the dorsal or upper-side of the hind-wing, this feature bulges outwards (see photo below, of Plain tiger butterfly in profile) and is called an alar pocket (7).

Danaus chrysippus bataviana male in profile showing alar pockets bulging on upper-side of hind-wing (white circle)
Danaus chrysippus bataviana male in profile showing alar pockets bulging on upper-side of hind-wing (white circle)

On the ventral, or underside, of the hind-wing, the so-called, subtornal brand is also visible as a black spot, but unlike on the top (dorsal) side, it has a prominent white spot within it. This lies alongside the third wing vein from the left (or central) side of the hind-wing, looking down. This white spot is the surest way to identify a male. The female has no such black mark with a white centre (see directly below).

Danaus chrysippus bataviana female on Rinca Is (Komodo National Park, Indonesia).
Danaus chrysippus bataviana female on Rinca Is (Komodo National Park, Indonesia).
Danaus chrysippus bataviana male
Danaus chrysippus bataviana male

Male milkweed butterflies (subfamily, Danainae, in the family Nymphalidae) have a pair of specialised scent-producing organs, called hair-pencils, at the tip of their abdomens. During courtship the hair pencils are everted to form two round bundles of hairs that look rather like toilet brushes! (See image on website below, #9). The function of these organs is to brush the females antennae and transfer a fine dust of pheromone particles. If the female is responsive to this advance, she flies down to the ground, where the male joins her.

Danaus chrysippus bataviana male in flight
Danaus chrysippus bataviana male in flight

It is known that the hair pencils of the male are first inserted into their alar pockets in order to make contact with the glands in this organ which produce a pheromone. Presumably they do this before everting the bristles? Males are unable to excite the females into copulation without first extracting the substance emanating from these alar glands. Armed with the dust-like pheromone particles he is able to dance in front of the female and transfer the magic potion!

Danaus chrysippus bataviana male nectaring and showing abdomen
Danaus chrysippus bataviana male nectaring and showing abdomen

There is however, no guarantee that the female will be receptive. Females might reject males for a number of reasons; he just might not look right (being a different subspecies perhaps); he might be too small (she may be seeking a large spermatophore produced by a large male); he might not smell right (the sex pheromones and volatile cuticular hydrocarbons); or she may have already mated (1). Bad luck! She indicates her refusal by bending her abdomen in a certain way and flapping her wings. It would be nice to be able to photograph these behaviours.

But if the courtship sequence is successful, the pair will remain locked together in copula for a good number of hours. Smith (2014) recorded an average time of 3.5 hours in copula for captive D. chrysippus (5), with some couples remaining together for up to 5 hours. The pair fly off together in what is called a post-nuptial flight. According to Smith (2014), the male is usually larger than the female – although other websites, including Wikipedia, state that the male plain tiger is smaller than the female – and he easily carries her off to a site where they can remain undisturbed for the remainder of the time they are locked together. The male aedeagus (penis) fits into a pocket beneath the ovipositor of the female and the sex organs are locked tightly together whilst the spermatophore is transferred. The female remains passive with limbs folded (see photo below). Smith (2014) reports a sighting of large female carrying a smaller male, so as is often the case in biology, there are no hard and fast rules about who is on top! It is possible that there is variation between subspecies with regard to size and role in terms of who is carrying whom?!

Danaus chrysippus bataviana male and female in copulation
Danaus chrysippus bataviana male and female in copulation

Much of this blog was based on information contained in the excellent volume on African Queens by David Smith, FRES, FLS. The main focus of the book is Danaus chrysippus (L.) sensu strico, which he considers is a ‘superspecies’ – a ‘complex of actively evolving populations’ comprising ‘incipient (imperfectly formed but actively evolving) semi- and subspecies’, rather than a single polymorphic species. Recent research has however, suggested that the D. chrysippus species complex should be separated into two separate species: a polytypic – meaning containing more that two subspecies – D. chrysippus, and monotypic D. petilia.  So not a very big change, as most of the subspecies remain. These two new species occur in distinct but contiguous areas, separated by Lydekker’s Line, separating Australian and Oriental faunas (see map in reference 1). Danaus petilia, known as the Lesser Wanderer, is a migratory species, found in Australia (8).

Whether there are one, two or three species, or seven or eight subspecies – or semi-species – need not concern us! Such matters are best left to taxonomists to sort out! As far as I am concerned it is a beautiful butterfly and I look forward to seeing and photographing some more of the different forms of this butterfly, which represents evolution in action.

Whilst writing this blog, I came across a similar account of mating in Plain tigers by another blogger: Krishna Mohan (10).

All of these images, apart from the one of the female from Komodo NP, were taken in Bali Barat NP, Bali, Indonesia, in October 2016.

  1. Braby, M. F., Farias Quipildor, G. E., Vane-Wright, R. I., & Lohman, D. J. (2015). Morphological and molecular evidence supports recognition of Danaus petilia (Stoll, 1790)(Lepidoptera: Nymphalidae) as a species distinct from D. chrysippus (Linnaeus, 1758). Systematics and Biodiversity, 13(4), 386-402.
  2. Lushai, G., Zalucki, M. P., Smith, D. A., Goulson, D., & Daniels, G. (2005). The lesser wanderer butterfly, Danaus petilia (Stoll 1790) stat. rev.(Lepidoptera: Danainae), reinstated as a species. Australian Journal of Entomology, 44(1), 6-14.
  3. http://butterflycircle.blogspot.co.uk/2010/11/life-history-of-plain-tiger.html
  4. Lovalekar, R., K. Saji, T. Bhagwat & Manoj P. 2017. Danaus chrysippus Linnaeus, 1758 – Plain Tiger. Kunte, K., P. Roy, S. Kalesh and U. Kodandaramaiah (eds.). Butterflies of India, v. 2.24. Indian Foundation for Butterflies.
    http://www.ifoundbutterflies.org/sp/744/Danaus-chrysippus
  5. Smith, D. A. (2014). African queens and their kin: a Darwinian odyssey. Taunton, UK: Brambleby Books.
  6. Smith, D. A., Gordon, I. J., & Allen, J. A. (2010). Reinforcement in hybrids among once isolated semispecies of Danaus chrysippus (L.) and evidence for sex chromosome evolution. Ecological Entomology, 35(s1), 77-89.
  7. Urquhart, F. A. 1976. Alar pocket of the male Monarch butterfly (Danaus p. plexippus) (Danaidae: Lepidoptera). Canadian Entomologist 108:777-782.
  8. http://www.brisbaneinsects.com/brisbane_nymphs/LesserWanderer.htm
  9. http://www.flickriver.com/photos/lionyang/2228664296/
  10. http://drkrishi.com/mating-trouble/

Bluff and deception in Blues

Longbanded Silverline (Spindasis lohita)
Longbanded Silverline (Spindasis lohita)

The Longbanded Silverline (Spindasis lohita), Family Lycaenidae, is a beautiful insect with a remarkable structure – a tail, or ‘false head’ – at the end of its hind wing. There is a bright orange tornal patch – the tornus is the posterior corner of the butterfly wing – on both sides of the wing. There is also a black eye-spot and two pairs of white-tipped, filament-like black tails, or ‘false antennae’, at the end of the wing. Interestingly, many lycaenids have similar black and orange eye-spots and single or double tails.  For example, the Common Tit (Hypolycaena erylus himavantus) also has white-tipped, double tails similar to this species (1). So presumably it was a feature that evolved at sometime during the history of this family. Black and orange make a very eye-catching colour combination.

It is widely assumed that these structures are a ‘false head’ (or ‘fake head’), which acts to divert predatory attacks, e.g. bird pecks, away from the real head (and body) and towards the back of the butterfly. There is plenty of evidence that butterflies really do get pecked at, or on, these hindmost eye-spots (2). It is surprising therefore, that very little rigorous experimentation has been carried out to thoroughly investigate this phenomenon. In other words, the ‘false head’ hypothesis has not been tested scientifically. That is not to say it is not true, it is just a subject that ‘remains ripe for testing’ according to Professor Martin Stevens (3).

Long-banded Silverline (Spindasis lohita) - close-up of false head
Long-banded Silverline (Spindasis lohita) – close-up of false head

The fact that these butterflies invest so much time and energy into producing these deceptive structures and moving the little tails about like false antennae, is to my mind, quite convincing circumstantial evidence for their utility in avoiding predation, or surviving an attack. It is clear how prominent the ‘false head’ is – and might appear to a bird – when looking down on the butterfly from above (see photo below) like a bird might see it. The real head is partly hidden underneath the wings, but the ‘false head’ is very prominent.

Long-banded Silverline (Spindasis lohita), looking down from above
Long-banded Silverline (Spindasis lohita), looking down from above

The lovely wing colours of this butterfly are a tapestry, to borrow a term used by lepidopterists, of tiny overlapping scales of different colours: red, silver, orange, white and black. The scales can be seen in two excellent close-up photographs of the wings of this butterfly on this webpage (4). Males of this species also have bright, iridescent blue patches on both dorsal fore- and hind-wings. It is possible that these, together with the contrasting orange patches, could also act to startle and deter a predator and give the butterfly time to make its escape.

  1. https://rcannon992.com/2015/01/30/pushmi-pullyu-butterfly/
  2. https://rcannon992.com/2016/01/17/peck-me-here-butterfly-predation/
  3. Stevens, M. (2016). Cheats and Deceits: How Animals and Plants Exploit and Mislead. Oxford University Press.
  4. http://butterflycircle.blogspot.co.uk/2010/09/life-history-of-long-banded-silverline.html