Herpetology Notes, volume 13: 925-929 (2020) (published online on 16 November 2020)

First record of male-male aggressive behaviour in the yellow- striped poison frog, Dendrobates truncatus Cope, 1861 (Anura: Dendrobatidae), with description of the aggressive call

Yeison Tolosa1,*

Territoriality has been observed in many animal Urabá, Caribbean region, and lowlands of the piedmont species and implies the defence of a relatively fixed site of central and western cordilleras (Frost, 2020; Páez et (Kaufmann, 1983). The defence of a territory enables al., 2002), between 10 and 1800 m a.s.l. Currently, there access to potential mates, reproduction areas, calling is few information about the aggressive behaviour and sites, hiding places, food, water, among others. Although vocalisation in this species. Although there are some obtaining these resources is energetically costly, they descriptive approximations of the advertisement call, might be necessary for the survival and reproductive this is an onomatopoetic presumption (like a “buzz success of individuals (Howard, 1978; Dhondt and call”), and the authors argue that advertisement call Schillermans, 1983; Whitham, 1986). One way of is infrequent because this is not easy to detect (Myers defending territories is through social interactions, and Daly, 1976). However, vocally active males were such as advertisement behaviour and contests, widely observed in a population of Tolima in the Mariquita humid observed in animals (Wells, 1977; Kluge, 1981; Dhondt forest (B. Rojas, pers. comm.). Gualdrón-Duarte et al. and Schillermans, 1983; Whitham, 1986). (2016) provides a short description of the advertisement In Dendrobatidae frogs, aggressive interactions are call, composed of a dominant frequency between 1.8- common and consist of visual displays, chases, calls 2.5 kHz and note rate of 59 notes/ second. Erdtmann and wrestling (Crump, 1972; Bunnell, 1973; McVey et and Amézquita (2009) described its advertisement call al., 1981; Sullivan et al., 1995; Pröhl, 2005; Méndez- with a duration of 2.35 s, a dominant frequency of 3.1 Narváez and Amézquita, 2014). Indeed, aggressive kHz and a note rate of 57.9 notes/s. Herein I describe interactions have been reported in males of the genus for the first time aggressive behaviours in D. truncatus, Oophaga (Galeano and Harms, 2015; Yang et al., 2018), involving two communication channels, the acoustic Colostethus (Duellman, 1966), Dendrobates (Summers, and the visual. 1992; Rojas and Pašukonis, 2019), Silverstoneia On 16 November 2016, I registered one aggressive (Summers, 2000), and Phyllobates (Summers, 2000; encounter between two males of Dendrobates truncatus Zimmerman and Zimmerman, 1985). in the locality “Reserva Natural El Neme”, municipality The yellow-striped poison frog, Dendrobates truncatus of Coello, Department of Tolima, Colombia (4.2868° N; (Cope, 1861), is a diurnal species, endemic of Colombia 74.9225° W, 379 m a.s.l.), between 16:00h and 17:00h. and presumably aposematic. It is found in the lowest The full record of the aggressive encounter was filmed stratum of humid and dry forests (Castro and Lynch, with a Canon PowerShot SX60HS digital camera and 2004), along the Magdalena Valley, western Gulf of housed in YouTube (https://youtu.be/y0XIhXrTx28). The aggressive behaviours were categorised, with modifications, according to Baugh and Foster (1994) (Table 1). Spectral and temporal parameters of the aggressive call of D. truncatus were described following Köhler et al. (2017). I considered the aggressive call of D. truncatus 1 La Cumbre, Proyecto de divulgación en Biología & Astronomía, Vereda Asociadas Km 20, Santa Isabel, Tolima, as a distinctive sound produced in an exhalation of air, 730560, Colombia. during an encounter between at least two males (Toledo * Corresponding author. E-mail: [email protected] et al., 2014). A call is separated from other calls by a 926 Yeison Tolosa

Table 1. Description of the aggressive behaviours in Dendrobates truncatus in the municipality of Coello, Tolima, Colombia, Table 1. Description of the aggressive behaviours in Dendrobates truncatus in the municipality of Coello, according to Baugh and Foster (1994). Tolima, Colombia, according to Baugh and Foster (1994).

Behaviour Description Calling Vocalisation is a common outcome of male-male encounters. The calling male orients toward his opponent, inflates his vocal sac and emits an aggressive call. Locomotion Spontaneous displacement from one place to another without any aggressive stimulus. Tracking It can be either static, when a frog orients its body towards other frog without locomotion, or with an advance, when the male orients towards its conspecific while moving forward. Chase One male retreats following an encounter (visual, acoustic or both), and the other one pursues him. Escape In response to aggressive behaviour, one frog attempts to hide beneath the substrate or escape. Statue behaviour In response to aggressive behaviour, the submissive frog freezes in one position. Wrestling Physical contact that results from the chase. This behaviour can be divided into snout blows (Fig. 1F and 1I), and crush behaviour (Fig. 1G, 1H and 1J), in which one frog presses the other to the ground by sitting on him (see Baugh and Foster, 1994).

period of silence, typically much larger than the call of fast strokes with forehead movements, here called (Köhler et al., 2017). For the analysis of the calls, I “snout blows” (Table 1; Fig. 1F and 1I). At times, a extracted the audio file from the video in WAV format, contestant stood on top of the other with movements which was visualised in Raven Pro 1.3 (Cornell Lab pushing him toward the ground, which lasted almost of Ornithology) using the Blackman Algorithm with a 120 seconds. This behaviour, denominated “crush window size of 256, and in R Studio using the seewave behaviour”, may prevent movement from the opponent and tuneR packages (Sueur and Simonis, 2008; R Studio and was reported in Oophaga pumilio (Table 1; Fig. 1G, Team, 2015; Uwe et al., 2018). 1H, 1J; Baugh and Foster, 1994). The contestant that Prior to the initiation of the agonistic encounter, the was underneath continued to jump until it was released, males were far away from each other (roughly 5 m), after which the chases and escapes continued and ended calling from their locations with no apparent visual in wrestling. Finally, the contestants decreased both the contact. The aggressive encounter began with the arrival escapes and chases, and the aggressive encounters. Once of an intruder male within the calling site of a resident males stopped wrestling, each one vocalised from their male, accompanied by a series of aggressive calls, and new locations (ca. five meters distant from each other), lasted ca. 712 seconds. The interaction took place close indicating the end of the agonistic interactions. to a brook, on trunks, branches and leaf litter. When I quantified the budget time as the percentage of the the intruder emitted an aggressive call, the resident behaviours exhibited between the two males during displayed a behaviour called “tracking-static” (Baugh the whole aggressive encounter, based on the video and Foster, 1994), in which one male orients his body in recording. The most prominent was wrestling (30.25% the direction of the other male without locomotion (Table of the total duration) followed by chases (21.07%), 1; Fig. 1C), probably tuning and locating the origin of showing that the aggressive behaviour between them the signal. After this behaviour, the resident male usually involved mostly physical contact. Also, statue behaviour emitted an aggressive call, as an antagonistic response was observed 19.88% of the time, and is considered a to the call of the intruder. The vocal dispute among passive behaviour resulting from a chase or escape (Fig. contestants generated a behaviour of approaching 1A). Escapes (12.40%) were displayed after wrestling towards the opponent, called “advance tracking” (Table or calling. Likewise, males performed calling (11.44%) 1). This proximity caused a series of chases and escapes as an antagonistic response to an acoustic or visual (Table 1; Fig. 1D and 1E), followed by a vocal dispute behaviour. The advance tracking behaviour occurred less with some tracking-static behaviours, in which acoustic frequently (3.05%), because this behaviour is displayed and visual contact remained despite not moving towards before the chases. When males moved towards or to each other. In general, the chases and escapes ended in avoid the opponent, I considered this as chase or escape, physical contact or wrestling. Wrestling is composed respectively. Finally, locomotion (Table 1) was the less First record of male-male aggressive behaviour in the yellow-striped poison frog 927

Figure 1. Aggressive behaviours observed between two males of Dendrobates truncatus (Coello, Tolima, Colombia). (A) Statue behaviour; (B) Vocalisation, (C) Tracking-static; (D) Chase; (E) A male performs a chase while the other escapes; (F, I) Snout blows; (G, H, J) Crush behaviour. Photographs and illustrations by the author.

represented behaviour (1.86%), since it was considered was 3.78 ± 0.17 kHz (3.45-4.06 kHz, N = 19 calls from spontaneous without any relation with acoustic, visual two males). or aggressive behaviour. Locomotion occurred in the The aggressive encounter of D. truncatus included first seconds of the aggressive encounter and in some mostly a combination of wrestling and chases final moments when the intensity decreased. (approximately half of the time). Chases, escapes, The aggressive call of D. truncatus was a pulsed call acoustic and visual exhibitions can be considered as composed of several notes distributed in pulse groups behaviours that increase the probability of physical (Buzz call) (Fig. 2). The following results are shown contact between intruder and resident. These intrasexual as average ± standard deviation (range; number of physical aggressions are arguably costly in terms of observations). Aggressive call duration was 1.60 ± 0.56 energy, and can increase the risks of both contestants to s (0.81 - 2.81 s, N = 19 calls from two males). Calls be seriously injured (Maynard-Smith and Price, 1973; were composed by 105.57 ± 32.89 notes (56 - 180 notes, Maynard-Smith and Harper, 2003). To avoid these costs, N = 19 calls from two males). Notes had a duration of intraspecific conflicts may occur as a “limited war” type, 0.006 ± 0.0018s (0.0038 - 0.0101 s, N = 2006 notes involving inefficient weapons or “ritualised behaviours” from 19 calls from two males) and inter-note duration of that seldom cause serious injury to either contestant, so 0.0090 ± 0.0013 s (0.0062 - 0.0115 s, N = 1968 intervals that the contestant that fights the longest wins the contest from 19 calls from two males). The note repetition rate (Maynard-Smith and Price, 1973). To that sense, if was 68.73 ± 8.84 notes/s (56-99 notes/s, N = 2006 notes most members of a population adopt a specific strategy from 19 calls from two males). The dominant frequency (without a “mutant” strategy that would give higher 928 Yeison Tolosa

Figure 2. Spectrogram (top), oscillogram (middle) and power spectrum (bottom) of an aggressive call in Dendrobates truncatus, municipality of Coello, Colombia. Figures (A), (B) and (C) depict the aggressive call, and figures (D), (E) and (F) represent notes with pulse groups.

reproductive fitness), then it will be transmitted to Acknowledgments. I am very grateful to the museum team future generations with higher frequencies compared to of biological collections of Villa de Leyva of the Instituto other strategies (the Evolutionary Stable Strategy - ESS; Humboldt (Boyacá, Colombia) for giving me the opportunity Maynard-Smith and Price, 1973). Hence, all behaviours to share the academic and learning environment. This work was made possible by the project “Diseño de dos corredores de observed in D. truncatus can be considered as “ritualised conectividad ecológica en fragmentos de bosque seco tropical behaviours”, so visual and acoustic displays might en el departamento del Tolima”, convenio 026, Universidad del be selected over physical aggression. The aggressive Tolima-Cortolima. I thank Sandra V. Flechas, Ana María Ospina- encounters documented in other dendrobatids and Larrea, Estefanía Guzmán, and referees for their comments. I am also in D. truncatus often include physical aggression, immensely grateful to Zuania Colón for her advice in R Studio when visual and acoustic displays are recalcitrant in and finally Bibiana Rojas for her advice on both the manuscript the contest (Duellman, 1966; Goodman, 1971; Crump, and the English version. 1972; Silverstone, 1973; Summers, 1992; Summers and Amos, 1996; Summers, 2000; Pröhl, 2005; this study). References The type of wrestling observed in D. truncatus rarely Baugh, J.R., and Forester, D.C. (1994): Prior residence effect in injures the contestants, and thus we hypothesise that the dart-poison frog, Dendrobates pumilio. Behaviour 131: visual, acoustic and physical aggression can be selected 207–224. as ESS, and the winner will be the one that fights the Bunnell, P. (1973): Vocalizations in the territorial behaviour of the longest using these ritualised behaviours. frog Dendrobates pumilio. Copeia 1973: 277–285. First record of male-male aggressive behaviour in the yellow-striped poison frog 929

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