Experimental elevation of wildlife testosterone using silastic tube implants

Area of Science:

• Endocrinology
• Animal Behavior
• Wildlife Research

Background:

• Testosterone (T) is a crucial androgen influencing vertebrate behavior and reproduction.
• Manipulating T levels is valuable for researchers in animal behavior and reproductive studies.
• Silastic implants offer a method for sustained hormone delivery in wildlife.

Purpose of the Study:

• To review the use of silastic implants for hormone manipulation in wildlife.
• To present a method for manipulating testosterone levels in rock hyraxes (Procavia capensis) using silastic implants.
• To assess the efficacy and optimal dosage of silastic implants for T elevation.

Main Methods:

• In vitro and in vivo experiments to test silastic tube and glue secretion patterns.
• Measurement of endogenous T levels in wild-captured rock hyraxes.
• Insertion of T-filled silastic implants to elevate T levels.
• Analysis of factors predicting T levels and implant T depletion.

Main Results:

• Silastic tubes and glue exhibited similar secretion patterns.
• Seven 20mm implants were identified as the optimal dose for elevating T to maximal physiological concentrations.
• Implant insertion number predicted T levels; duration influenced remaining T in implants.
• Testosterone implants successfully induced sexual behaviors during the non-reproductive period.

Conclusions:

• Silastic implants provide a versatile and effective tool for manipulating testosterone levels in wildlife.
• This method allows for elevation of T to maximal breeding levels during non-breeding periods.
• The findings support the use of T implants for advancing wildlife behavioral and reproductive research.