Mimic Spotlight: The Superb Lyre Bird (Menura superba)

Throughout the semester I've predominantly discussed visual mimicry, so I thought for the last "official" post I'd cover something a bit different; the Superb Lyre Bird. 

The Superb Lyre Bird (Menura superba) is a fairly well known example of vocal mimicry among birds, having the most complex syrinx of any Passerine (song bird) which gives it an unrivaled vocal repertoire and ability to mimic almost any sound imaginable. 

Figure 1: Superb Lyre Bird (Menura superba)

The song of the Lyre Bird is comprised of a mixture of its own song and a number of mimicked sounds/noises; Lyrebirds most commonly mimic other birds, or other animals (eg; koalas and dingoes). The male Lyrebirds call throughout the year, but are most intense during the breeding season (June to August) when they call and dance (showing off their tail feathers) to attract a female. The female Lyrebirds can also sing, but they are generally less skilled than the males (That's sexual selection for you).

Figure 2: Superb Lyre Bird (Menura superba)

FUN FACTS TIME! 

In addition to learning sounds from their environment, Lyrebirds can pass on sounds to other individuals, enabling songs to be passed on from generation to generation. Flute-like calls have been observed in a small number of Lyrebird individuals, and thanks to research by Neville Fenton after he observed such flute mimicry in 1969, it was discovered that this flute mimicry was originally learned by a pet Lyrebird in the 1930s.

Individual Lyrebirds have been known to mimic some very strange and unique sounds. Some of the more abstract examples of Lyrebird mimicry include; computer game sounds, car alarms, chainsaws and even the human voice.

- National Film and Sound Archive, Sounds of Australia
- Tapper, James (7 May 2006). "The nation's favourite Attenborough moment". Daily Mail (Daily Mail Online).
- Lill, Alan (2004), "Family Menuridae (Lyrebirds)", in del Hoyo, Josep; Elliott, Andrew; Christie, David, Handbook of the Birds of the World. Volume 9, Cotingas to Pipits and Wagtails, Barcelona: Lynx Edicions, pp. 484–495
- Reilly, P.N. (1988). The Lyrebird: A Natural History. Kensington, NSW: New South Wales University Press

- Figure 1: http://ih2.redbubble.net/image.8010946.1140/flat,550x550,075,f.jpg, photo by Donovan Wilson, retrieved 29/05/14.
- Figure 2: http://www.duadepaton.com/wp-content/uploads/2013/06/350-Superb-Lyrebird-North-Nowra-1061.jpg, unknown photographer, retrieved 29/05/14

Mimic Spotlight: The AntySpider (hurr hurr, puns)

Much like the Orchid Mantis I talked about in March, Myrmarachne melanotarsa uses mimicry both defensively and aggressively. This jumping spider (See Figure 1) is one of many jumping spider species which mimic ants, specifically the cocktail ant (Crematogaster sp.) in M. melanotarsa's case. 

Figure 1: Myrmarachne melanotarsa

Many jumping spiders (Salticidae) are afraid of ants, as they are often preyed on by the 6-legged fiends. Additionally ants are well-protected against salticids which might view ants as potential prey. For this reason it is common in ant-adverse jumping spiders, such as Menemerus sp. for the females to abandon their broods when in the presence of ants more often than when in the the presence of other salticids. Ants have trouble navigating the web-built nests of jumping spiders, and hence it is usually safe for mothers to leave their brood unattended for a short time as the risk of predation by ants is low.

Our ant-mimic uses this behaviour to its advantage, as it raids the abandoned nests of the aforementioned Menemerus sp. for eggs and newly-born young. Unlike the ants it mimics, M. melanotarsa has no difficulty entering the nest (it is a spider, after all). The figure below shows that M. melanotarsa is often mistaken for an ant by the females of  Menemerus sp - indicating a successful mimetic display by M. melanotarsa. 

Figure 2: Frequency of test spider (Menemerus sp.) females remaining inside nest with hatchlings or vacating nest when surrounded by groups of 20 individual ants (Crematogaster sp.), ant-like salticids (M. melanotarsa), non-ant-like salticids (Menemerus sp. and Pseudicius sp.), midges (Chaoborus sp.) and empty stimulus chambers (control). Black = outside nest; grey = inside nest.

In addition to the aggressive uses of its mimicry, M. melanotarsa also gains some protection from its ant disguise. As mentioned earlier, ants pose a serious threat to salticids - so jumping spiders tend to avoid ant encounters whenever possible. As a result, salticids which prey on other jumping spiders often mistake M. melanotarsa as an ant, and hence, our mimic avoids being eaten. Success. 

While Batesian mimicry relies on being seen by a potential predator, aggressive mimicry relies on blending in; not being seen. Other salticids, such as Cosmophasis bitaeniata, use this ant disguise to infiltrate ant nests and prey on the eggs. It is due to this that ant-mimicing spiders are generally regarded as being aggressive mimics, because the defensive aspect of their mimicry is a considered a secondary benefit.

- Nelson, X. J. and Jackson, R. R. 2009, ' Aggressive use of Batesian mimicry by an ant-like jumping spider', Biology Letters, vol. 5, pp. 755-757

- Figure 1: http://img3.rnkr-static.com/user_node_img/50007/1000134056/full/myrmarachne-melanotarsa-photo-u3.jpg, unknown photographer, retrieved 02/05/14
- Figure 2: Nelson, X. J. and Jackson, R. R. 2009, ' Aggressive use of Batesian mimicry by an ant-like jumping spider', Biology Letters, vol. 5, pp. 756