Table 1.
Examples of different approaches to unit definition, from different taxa and with different research aims.
| Unit criterion | Taxon | Goal of division into “units” | |||
|---|---|---|---|---|---|
| Descriptive | Production | Perception | Function (in bold) | ||
| Separated by silence | Birds | Swamp sparrow Melospiza georgiana note (Marler & Pickert, 1984) Black-capped chickadee Poecile atricapillus note (Nowicki & Nelson, 1990) Red-legged partridge Alectoris rufa and rock partridge A. graeca (Ceugniet & Aubin, 2001) |
Zebra finch Taeniopygia guttata syllable (Cynx, 1990) Emperor penguin Aptenodytes forsteri (Robisson et al., 1993) Canary Serinus canaria breaths (Hartley & Suthers, 1989) |
Swamp sparrow Melospiza georgiana note (Nelson & Marler, 1989) Black-capped chickadee Poecile atricapillus notes (Sturdy et al., 2000; Charrier et al., 2005) King penguin Aptenodytes patagonicus (Lengagne et al., 2001) |
Carolina chickadee Poecile carolinensis and black-capped chickadee P. atricapillus note composition → predator, foraging activity, identity(Freeberg, 2012; Krams et al., 2012) King penguin Aptenodytes patagonicus → individual identities (Jouventin et al., 1999; Lengagne et al., 2000) Emperor penguin Aptenodytes forsteri → individual identities (Aubin et al., 2000) |
| Terrestrial mammals | Meerkat Suricata suricatta calls (Manser, 2001) Gibbon Hylobates lar phrase (Raemaekers et al., 1984) Rock hyrax Procavia capensis songs (Kershenbaum et al., 2012) Free-tailed bat Tadarida brasiliensis syllable (Bohn et al., 2008) Mustached bat Pteronotus parnellii syllable (Kanwal et al., 1994) |
Lesser short-tailed bat Mystacina tuberculata pulses (Parsons et al., 2010) | Meerkat Suricata suricatta calls (Manser, 2001) | Meerkat Suricata suricatta calls → predator type (Manser, 2001) Rock hyrax Procavia capensis songs → male quality (Koren & Geffen, 2009) Free-tailed bat Tadarida brasiliensis syllable → courtship (Bohn et al., 2008; Parsons et al., 2010) |
|
| Marine mammals | Humpback whale Megaptera novaeangliae unit (Payne & McVay, 1971) Killer whale Orcinus orca calls (Ford, 1989) Bottlenose dolphin Tursiops truncatus signature whistles (Caldwell, 1965; McCowan & Reiss, 1995) Australian sea lion Neophoca cinerea barking calls (Gwilliam et al., 2008) |
Humpback whale Megaptera novaeangliae song (Adam et al., 2013) | Bottlenose dolphin Tursiops truncatus signature whistles (Janik et al., 2006) Subantartic fur seal Arctocephalus tropicalis pup attraction call (Charrier et al., 2003) Australian sea lion Neophoca cinerea calls (Charrier & Harcourt, 2006) |
Bottlenose dolphin Tursiops truncatus signature whistles → individual identity (Sayigh et al., 1999; Harley, 2008) Killer whale Orcinus orca calls → group identity (Ford, 1989) Australian sea lion Neophoca cinerea call → colony identity (Attard et al., 2010) Australian sea lion Neophoca cinerea call → threat level (Charrier et al., 2011) Australian sea lion Neophoca cinerea call → individual identity (Charrier et al., 2009; Pitcher et al., 2012) |
|
| Change in acoustic properties (regardless of silence) | Birds | Red junglefowl Gallus gallus elements (Collias, 1987) | Northern cardinal Cardinalis cardinalis song (Suthers, 1997) Anna hummingbird Calypte anna mechanical chirps (Clark & Feo, 2008) |
Anna hummingbird Calypte anna mechanical chirps (Clark & Feo, 2010) Male chickens Gallus gallus alarm calls (Evans et al., 1993) |
Blackcap Sylvia atricapilla song → species identity (Mathevon & Aubin, 2001) White-browed warbler Basileuterus leucoblepharus song → species identity (Mathevon et al., 2008) Yelkouan Shearwaters Puffinus yelkouan call → sex and mate identity (Cure et al., 2011) Grasshopper sparrow Ammodramus savannarum buzz/warble → territorial/social (Lohr et al., 2013) Rufous-sided towhee Pipilo erythrophthalmus song → species identity (Richards, 1981) |
| Terrestrial mammals | Black-fronted titi monkey Callicebus nigrifrons alarm calls (Cäsar et al., 2012b) Western gorilla Gorilla gorilla calls (Salmi et al., 2013) Red titi monkey Callicebus cupreus calls (Robinson, 1979) |
Banded mongoose Mungos mungo (Jansen, Cant & Manser, 2012) | Mustached bat Pteronotus parnellii composites (Esser et al., 1997) | Black-fronted titi monkey Callicebus nigrifrons alarm calls → predator type and behaviour (Cäsar et al., 2012a) Western gorilla Gorilla gorilla vocalisations → multiple functions (Salmi et al., 2013) Tufted capuchin monkeys Sapajus nigritus calls → predator type (Wheeler, 2010b) Banded mongoose Mungos mungo close calls → individual identity, group cohesion (Jansen et al., 2012) Spotted hyena Crocuta crocuta call → sex/age/individual identities (Mathevon et al., 2010) |
|
| Marine mammals | Bottlenose dolphin Tursiops truncatus whistle loops (Caldwell et al., 1990) Killer whale Orcinus orca, subunit of calls (Shapiro et al., 2010) Humpback whale Megaptera novaeangliae subunit (Payne & McVay, 1971) Leopard seal Hydrurga leptonyx calls (Klinck et al., 2008) |
False killer whale Pseudorca crassidens vocalisations (Murray et al., 1998) Bottlenose dolphin Tursiops truncatus tonal calls (Parsons et al., 2010) |
Bearded seal Erignatus barbatus trills (Charrier et al., 2013) | Killer whales Orcinus orca calls → sex/orientation (Miller et al., 2007) Spinner dolphin Stenella longirostris whistles → movement direction (Lammers & Au, 2003) |
|
| Series of sounds | Birds | Song sparrow Melospiza melodia phrases (Mulligan, 1966; Marler & Sherman, 1985) Blue-footed booby Sula nebouxii call (Dentressangle et al., 2012) |
Emberizid sparrow trills (Podos, 1997) | Zebra finch Taeniopygia guttata syllables (Cynx et al., 1990) Little owl Athene noctua syllables (Parejo et al., 2012) Song sparrow Melospiza melodia songs (Horning et al., 1993) |
Carolina chickadee Poecile carolinensis D-notes → food availability (Mahurin & Freeberg, 2009) Kittiwake Rissa tridactyla call → sex/individual identities (Aubin et al., 2007) Shearwaters Puffinus yelkouan, Puffinus mauretanicus, Calonectris d. diomedea call → species identity (Curé et al., 2012) |
| Terrestrial mammals | Black-fronted titi monkey Callicebus nigrifrons alarm calls (Cäsar et al., 2012b, 2013) Mustached bat Pteronotus parnellii syllable (Kanwal et al., 1994) Free-tailed bat Tadarida brasiliensis calls (Bohn et al., 2008) Hyrax Procavia capensis social calls (Ilany et al., 2013) Chimpanzee Pan troglodytes pant hoots (Notman & Rendall, 2005) |
Diana monkey Cercopithecus diana alarm calls (Riede et al., 2005) Domestic dog Canis familiaris growls (Riede & Fitch, 1999) |
Black-fronted titi monkey Callicebus nigrifrons (Cäsar et al., 2012a) Colobus Colobus guereza sequences (Schel et al., 2010) Tufted capuchin monkey Sapajus nigritus bouts (Wheeler, 2010b) |
Chimpanzee Pan troglodytes pant hoots → foraging (Notman & Rendall, 2005) Free-tailed bat Tadarida brasiliensis calls → courtship (Bohn et al., 2008) |
|
| Marine mammals | Humpback whale Megaptera novaeangliae phrases (Payne & McVay, 1971) Bottlenose dolphin Tursiops truncatus whistles (Deecke & Janik, 2006) Free-tailed bat Tadarida brasiliensis syllable (Bohn et al., 2008) |
Humpback whale Megaptera novaeangliae songs (Frumhoff, 1983; Payne et al., 1983; Mercado et al., 2010; Mercado & Handel, 2012) Bottlenose dolphin Tursiops truncatus whistles (Janik et al., 2013) |
Humpback whale Megaptera novaeangliae songs (Handel et al., 2009) Bottlenose dolphin Tursiops truncatus whistles (Pack et al., 2002) Weddell seal Leptonychotes weddelli vocalisations (Thomas et al., 1983) Harbour seal Phoca vitulina roars (Hayes et al., 2004) |
Bottlenose dolphin Tursiops truncatus signature whistles → individual identity, group cohesion (Quick & Janik, 2012) Humpback whale Megaptera novaeangliae phrases → unknown (Payne & McVay, 1971) |
|
| Higher levels of organisation | Birds | Canary Serinus canaria song (Lehongre et al., 2008) | Swamp sparrow Melospiza georgiana trills (Podos, 1997) Nightingale Luscinia megarhynchos song (Todt & Hultsch, 1998) Canary Serinus canaria song (Gardner et al., 2005) |
Song sparrow Melospiza melodia songs (Searcy et al., 1995) Zebra finch Taeniopygia guttata song (Doupe & Konishi, 1991) Canary Serinus canaria song (Ribeiro et al., 1998) |
Skylark Alauda arvensis songs → group identity (Briefer et al., 2013) White-browed warbler Basileuterus leucoblepharus song → individual identity (Mathevon et al., 2008) |
| Terrestrial mammals | Red titi monkey Callicebus cupreus syllable (Robinson, 1979) Free-tailed bat Tadarida brasiliensis songs (Bohn et al., 2008) |
Rhesus-macaque Macaca mulatta vocalisations (Fitch, 1997) | Putty-nosed monkey Cercopithecus nictitans sequences (Arnold & Zuberbühler, 2006a) Red titi monkey Callicebus cupreus syllable (Robinson, 1979) |
Chimpanzee Pan troglodytes phrases → group identity (Arcadi, 1996) Putty-nosed monkey Cercopithecus nictitans sequences → predators presence, group movement (Arnold & Zuberbühler, 2006a) Tufted capuchin monkeys Sapajus nigritus calls → predator type (Wheeler, 2010b) Spotted hyena Crocuta crocuta call → dominance rank identity (Mathevon et al., 2010) |
|
| Marine mammals | Humpback whale Megaptera novaeangliae theme and song (Payne & McVay, 1971) | Humpback whale Megaptera novaeangliae song (Cazau et al., 2013) | Humpback whale Megaptera novaeangliae song (Handel et al., 2012) | Humpback whale Megaptera novaeangliae song → mating display - female attraction/male- male interactions (Darling et al., 2006; Smith et al., 2008) | |