Out of sight, out of mind: The role of carcass burial and maintenance in reducing competition in Nicrophorus investigator

Abstract

Competition for ephemeral resources like carrion is intense among necrophagous insects, particularly burying beetles (Nicrophorus spp.), where reproductive success is limited by access to carcasses. Burial and post-burial maintenance behaviors are hypothesized to reduce carcass detection by competitors through the suppression of volatile organic compounds (VOCs). I investigated the relative importance of burial and maintenance in reducing discovery of small vertebrate carcasses by other carrion beetles. In a field study in a montane meadow in Colorado, I established can-based enclosures containing Peromyscus maniculatus carcasses under three treatments: surface (unburied), N. investigator pairs allowed to bury carcasses, but then removed to prevent further maintenance, and -N. investigator pairs allowed to bury carcasses and continue maintenance behaviors. Carcasses were protected from direct intrusion but exposed to visiting insects via screened funnel traps. Over two trials of daily monitoring (3 days each) and one trial of delayed monitoring (7 days), I recorded visitor identity, sex, and size, and measured burial depth and soil temperature. Surface and unburied carcasses had significantly higher discovery rates than buried carcasses (χ² = 7.83, p = 0.005). Across all treatments, discovery proportions differed significantly (Fisher’s exact test, p = 0.011), with maintained carcasses having the lowest detection. Mean visitor counts trended higher for surface carcasses, though differences were not significant (p = 0.096). Burial depth did not significantly influence discovery (p = 0.586), indicating that even shallow burial reduced detection. These findings support the hypothesis that burial and maintenance function as effective exploitative competition strategies in N. investigator, likely mediated through VOC suppression. Such behaviors may contribute to priority effects that facilitate competitive coexistence. Future work should examine habitat- specific VOC dynamics and the individual contributions of maintenance behaviors.

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