Intraspecific communication via chemosignals has been linked to important natural history aspects... more Intraspecific communication via chemosignals has been linked to important natural history aspects in lizards, including honest signaling tied to reproductive success and conspecific displays of sociality. Chemosignals can be used over significant spatial and temporal parameters, allowing for inconspicuous interaction by some species. This type of cryptic communication is not easily detected, but researchers can obtain baseline lizard signaling capabilities by quantifying tongue-flick (TF) rate toward conspecific scents. We tested chemosignaling behavior in endangered Guatemalan Beaded Lizards (Heloderma charlesbogerti) by evaluating TF response toward same-sex and opposite-sex conspecific stimuli and control treatments. Our suspected sources of pheromones for determining conspecific scent recognition were shed skin and used substrate. Age and reproductive cycle of trial subjects had no discernable effect on TF rate, but sex was a significant factor. Both males and females displayed differential TFs between treatments from opposite-sex and same-sex donor individuals. Male lizard TF response was significantly different between all treatments, including controls. Females had lower and less pronounced differential TFs towards treatments than males, as female TF response was only significantly different between opposite-sex stimuli towards control and same-sex stimuli treatments. We conclude that nonvolatile chemosignals are present in H. charlesbogerti biomaterials, with the degree of behavioral response varying depending on sex and presented stimuli. Our study not only adds to our understanding of intraspecific chemosignaling in helodermatid lizards, but also provides information that could lead to more comprehensive conservation programs for H. charlesbogerti.
Misdirected amplexus can yield disadvantages, including higher risk of predation and potential re... more Misdirected amplexus can yield disadvantages, including higher risk of predation and potential reproductive interference (Höbel 2005. Herpetol. Rev. 36:439–440), especially if prolonged mate-guarding is common (Pearl et al. 2005. Am. Midl. Nat. 154:126–134). Published intergeneric amplexus is rare amongst tropical hylids (Streicher 2010. Herpetol. Rev 41:208) and rarer still are interfamilial amplexus events. Observations of Boana intergeneric (Pedro 2020. Herpetol. Notes 13:791–793; García-Ayachi 2022. Herpetol. Rev 53:283) and interfamilial (Avelar 2018. Herpetol. Rev 49:299–300) amplexus have been documented, but not in the genus Cochranella. On 4 December 2022, at 2200 h in the Osa Peninsula near Puerto Jimenez, Puntarenas Province, Costa Rica (precise location withheld at request of landowner), we observed an adult Cochranella granulosa (Centrolenidae) in amplexus with a juvenile Boana rosenbergi (Hylidae; Fig. 1). The frogs were on a broad leaf ca. 2.5 m above a small stream. Weather conditions were 23.9°C, with a rain shower earlier in the day. This time period coincides with the end of the wet season, potentially contributing to a lack of suitable conspecifics which may have encouraged this event, similar to relative abundance increasing the probability of reproductive interference observed in other anurans (Hettyey 2003. Behav. Ecol. 14:294–300). We would like to thank Brian Kubicki for confirming the species identification.
encompasses the provisioning or assistance of food to offspring (Whitaker, 2007), has been histor... more encompasses the provisioning or assistance of food to offspring (Whitaker, 2007), has been historically deemed a hallmark to birds and mammals and traditionally assumed non-existent in crocodilians (Balshine, 2012). Although crocodilian parental investment of attending eggs is nearly ubiquitous (Gans, 1996; Reynolds, et al., 2002; Moore and Varricchio, 2016), there are sparse examples of parental feeding in the literature. Published examples of crocodilian parental feeding has been reported twice in Crocodylus siamensis (Brueggen, 2001; Whitaker, 2007), once in Crocodylus palustris (Whitaker, 2007), on eight separate occasions in Alligator mississippiensis (Mcllhenny, 1987), and an apparent attempt by Crocodylus intermedius (Blohm, 1982). Caiman latirostris are a medium-sized crocodilian with adults typically measuring less than a total length of 2.0 m, and are considered the southernmost South American crocodilian by geographic range. Populations extend into Brazil, Bolivia, Paragu...
Unprovoked mouth gaping behavior is ubiquitous throughout 24 extant members of Crocodylia, yet in... more Unprovoked mouth gaping behavior is ubiquitous throughout 24 extant members of Crocodylia, yet information on gaping is limited. Proposed hypotheses for gaping include thermoregulation and the evaluation of potential environmental conditions. To determine temperature effects, we tracked head surface (T sh), body surface (T sb), and ambient (T a) temperatures with insolation utilization and positions. To evaluate potential environmental stimuli, we tested behavioral effects (i.e., open-eye frequency) and recorded conspecific presence, day and night events, and interaction with flies and fish. We included 24 extant species representatives, with detailed assessments of American Alligators (Alligator mississippiensis), Crocodylus siamensis, Crocodylus intermedius, Crocodylus rhombifer, and Crocodylus halli. Observations occurred during a range of T a (3.89-32.228C) with mean T sh consistently higher than both T sb and T a across all crocodilians. Differences in T sh and T a were most pronounced with head in the sun. However, no significant differences in T sh and T sb were detected for A. mississippiensis and Cr. siamensis. Conversely, Cr. halli, Cr. intermedius, and Cr. rhombifer demonstrated statistically higher T sh. Gaping with open eyes was more common, yet modeling suggested a relationship with closed eyes and temperature. Anecdotal observations indicated weather changes may elicit mouth gaping, and we report the second nocturnal mouth gaping observation (the first for three species). Overall, mixed results indicated unprovoked mouth gaping is a complex behavior, making it difficult to draw clear cause and effect relationships. Future research may benefit from a focus on natural history and quantitative behavioral studies.
Intraspecific communication via chemosignals has been linked to important natural history aspects... more Intraspecific communication via chemosignals has been linked to important natural history aspects in lizards, including honest signaling tied to reproductive success and conspecific displays of sociality. Chemosignals can be used over significant spatial and temporal parameters, allowing for inconspicuous interaction by some species. This type of cryptic communication is not easily detected, but researchers can obtain baseline lizard signaling capabilities by quantifying tongue-flick (TF) rate toward conspecific scents. We tested chemosignaling behavior in endangered Guatemalan Beaded Lizards (Heloderma charlesbogerti) by evaluating TF response toward same-sex and opposite-sex conspecific stimuli and control treatments. Our suspected sources of pheromones for determining conspecific scent recognition were shed skin and used substrate. Age and reproductive cycle of trial subjects had no discernable effect on TF rate, but sex was a significant factor. Both males and females displayed differential TFs between treatments from opposite-sex and same-sex donor individuals. Male lizard TF response was significantly different between all treatments, including controls. Females had lower and less pronounced differential TFs towards treatments than males, as female TF response was only significantly different between opposite-sex stimuli towards control and same-sex stimuli treatments. We conclude that nonvolatile chemosignals are present in H. charlesbogerti biomaterials, with the degree of behavioral response varying depending on sex and presented stimuli. Our study not only adds to our understanding of intraspecific chemosignaling in helodermatid lizards, but also provides information that could lead to more comprehensive conservation programs for H. charlesbogerti.
Misdirected amplexus can yield disadvantages, including higher risk of predation and potential re... more Misdirected amplexus can yield disadvantages, including higher risk of predation and potential reproductive interference (Höbel 2005. Herpetol. Rev. 36:439–440), especially if prolonged mate-guarding is common (Pearl et al. 2005. Am. Midl. Nat. 154:126–134). Published intergeneric amplexus is rare amongst tropical hylids (Streicher 2010. Herpetol. Rev 41:208) and rarer still are interfamilial amplexus events. Observations of Boana intergeneric (Pedro 2020. Herpetol. Notes 13:791–793; García-Ayachi 2022. Herpetol. Rev 53:283) and interfamilial (Avelar 2018. Herpetol. Rev 49:299–300) amplexus have been documented, but not in the genus Cochranella. On 4 December 2022, at 2200 h in the Osa Peninsula near Puerto Jimenez, Puntarenas Province, Costa Rica (precise location withheld at request of landowner), we observed an adult Cochranella granulosa (Centrolenidae) in amplexus with a juvenile Boana rosenbergi (Hylidae; Fig. 1). The frogs were on a broad leaf ca. 2.5 m above a small stream. Weather conditions were 23.9°C, with a rain shower earlier in the day. This time period coincides with the end of the wet season, potentially contributing to a lack of suitable conspecifics which may have encouraged this event, similar to relative abundance increasing the probability of reproductive interference observed in other anurans (Hettyey 2003. Behav. Ecol. 14:294–300). We would like to thank Brian Kubicki for confirming the species identification.
encompasses the provisioning or assistance of food to offspring (Whitaker, 2007), has been histor... more encompasses the provisioning or assistance of food to offspring (Whitaker, 2007), has been historically deemed a hallmark to birds and mammals and traditionally assumed non-existent in crocodilians (Balshine, 2012). Although crocodilian parental investment of attending eggs is nearly ubiquitous (Gans, 1996; Reynolds, et al., 2002; Moore and Varricchio, 2016), there are sparse examples of parental feeding in the literature. Published examples of crocodilian parental feeding has been reported twice in Crocodylus siamensis (Brueggen, 2001; Whitaker, 2007), once in Crocodylus palustris (Whitaker, 2007), on eight separate occasions in Alligator mississippiensis (Mcllhenny, 1987), and an apparent attempt by Crocodylus intermedius (Blohm, 1982). Caiman latirostris are a medium-sized crocodilian with adults typically measuring less than a total length of 2.0 m, and are considered the southernmost South American crocodilian by geographic range. Populations extend into Brazil, Bolivia, Paragu...
Unprovoked mouth gaping behavior is ubiquitous throughout 24 extant members of Crocodylia, yet in... more Unprovoked mouth gaping behavior is ubiquitous throughout 24 extant members of Crocodylia, yet information on gaping is limited. Proposed hypotheses for gaping include thermoregulation and the evaluation of potential environmental conditions. To determine temperature effects, we tracked head surface (T sh), body surface (T sb), and ambient (T a) temperatures with insolation utilization and positions. To evaluate potential environmental stimuli, we tested behavioral effects (i.e., open-eye frequency) and recorded conspecific presence, day and night events, and interaction with flies and fish. We included 24 extant species representatives, with detailed assessments of American Alligators (Alligator mississippiensis), Crocodylus siamensis, Crocodylus intermedius, Crocodylus rhombifer, and Crocodylus halli. Observations occurred during a range of T a (3.89-32.228C) with mean T sh consistently higher than both T sb and T a across all crocodilians. Differences in T sh and T a were most pronounced with head in the sun. However, no significant differences in T sh and T sb were detected for A. mississippiensis and Cr. siamensis. Conversely, Cr. halli, Cr. intermedius, and Cr. rhombifer demonstrated statistically higher T sh. Gaping with open eyes was more common, yet modeling suggested a relationship with closed eyes and temperature. Anecdotal observations indicated weather changes may elicit mouth gaping, and we report the second nocturnal mouth gaping observation (the first for three species). Overall, mixed results indicated unprovoked mouth gaping is a complex behavior, making it difficult to draw clear cause and effect relationships. Future research may benefit from a focus on natural history and quantitative behavioral studies.
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