Observations of Aggressive Defensive Display Behavior in P. platyrhinos
www.youtube.com/watch?v=MNTJy15ayv8
www.youtube.com/watch?v=e9JoSreKadE
www.youtube.com/watch?v=nPSBxIpap58
The subject is a male P. platyrhinos that has been captive here since being rescued and treated for respiratory illness and eye symptoms over a year ago. He came from southern Idaho with 3 other males at the same time ( all wild caught by the surrendering party's younger brother ), and resides in the same tank only with them. Occasionally, they are allowed to co-habitate for short periods for less than a day with other HLs, but particularly only P. solare for any length of time. This day, all HLs were basking together outdoors. Two of these four males have demonstrated defensive posturing before, with body tilting, juking, feigned biting and other posturing, but this one is the only one to demonstrate actual attempts to bite, and ever to successfully bite.
It was noted that his aggressive responses increased in proportion to the decrease in his avenues of escape. As he had more space to back up or turn, he was more likely to hop, run, tilt the body downward in the direction of the perceived attack, and only threatened to bite. When he had less room to escape, or was confronted with a more threatening frontal hand movement, he was more likely to actually bite. This is not surprising for some wild animals, but it is not typical in the horned lizard. Most in this situation still attempt escape, or remain absolutely still and close their eyes as the threat becomes more aggressive or closes on them. Others may attempt blood squirting at this point of agitation.
The P. platyrhinos is one of the leanest in build and most agile of the Phrynosoma native to the US. Many can actually jump an impressive height for a HL, and I have previously found one of them hanging half way up the side of the tank glass, suspended by his nails from a strip thermometer. He had launched from a nearby basking rock attempting to grab the sides of the tank, and actually did this repeatedly in one day. ( that is why I warn those of you with platyrhinos to watch how you stack your decor, as they also like to dig. )
This species seems to stand a better chance than others of actually getting away from a threat if it decided to run. This particular DHL appears to be the exception to the rule, in being so aggressive in standing his ground and actually biting, as opposed to just threatening to bite or even bloodletting.
Mike
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Wichita Falls Reptile Rescue
