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The soil burial context of a bird bone assemblage is affected by many different taphonomic factors. In this pilot study, we examined the potential effects of soil shrink-swell on white-tailed dove (Zenaida asiatica) bones experimentally buried in three soils of different clay contents. We predicted that bones buried in high clay soils would experience the most damage from soil shrink-swell. Dove wing and leg bones were buried and exposed to 60 days and eight episodes of cyclic soil shrink-swell. We recovered all bones (humeri, ulnae, radii, femora, and tibiotarsi) and found 77.1% of them to exhibit damage. Significant damage occurred among the humeri, ulnae, radii, and femora buried in high clay soil, supporting our prediction. Each bone experienced at least one of the 10 fracture types we recorded. We found the greatest damage in humeri, for which all experienced damage from pitting. The humeri sample also displayed eight fracture types across bone portions and landmarks. Our pilot study is exploratory and meant to provide information useful for further experimentation with additional bird bones using whole carcasses and excised specimens placed in additional positions and soil conditions.

We present a simulation model for risk assessment of the impact of insecticide inhibitors of cholinesterase (ChE) applied in irrigated agricultural fields on non-target wildlife. The model, which we developed as a compartment model based on difference equations (Δ t = 1 h), consists of six submodels describing the dynamics of (1) insecticide application, (2) insecticide movement into floodable soil, (3) irrigation and rain, (4) insecticide dissolution in water, (5) foraging and insecticide intake from water, and (6) ChE inhibition and recovery. To demonstrate application of the model, we simulated historical and “worst-case” scenarios of the impact of ChE-inhibiting insecticides on white-winged doves ( Zenaida asiatica ) inhabiting natural brushland adjacent to cotton and sugarcane fields in the Lower Rio Grande Valley of Texas, USA. Only when a rain event occurred just after insecticide application did predicted levels of ChE inhibition surpass the diagnostic level of 20% exposure. The present model should aid in assessing the effect of ChE-inhibiting insecticides on ChE activity of different species that drink contaminated water from irrigated agricultural fields, and in identifying specific situations in which the juxtaposition of environmental conditions and management schemes could result in a high risk to non-target wildlife.

Electrographic and behavioral observations were made in five adult birds of the genus Zenaida asiatica. Five different vigilance states were quantitated: (1) Active waking (Aw) was characterized by constant behavioral activity; the nuchal electromyogram was tonically active with bursts associated to movements. The electroencephalographic pattern was low voltage and high frequency. (2) Quiet waking (Qw) was characterized by diminished behavioral activity and the EEG pattern was similar to that of Aw. (3) Drowsiness (D) was characterized by behavioral calm. Frequency of cerebral activity diminished progressively, but there were short periods of desynchronization corresponding to brief awakenings. (4) Slow wave sleep (SWS); during this period there was behavioral rest and EEG pattern of continuous slow waves and the nuchal EMG was tonically reduced. Spindles of sleep were not observed. (5) Paradoxical sleep (SP), behaviorally characterized by phasic manifestations consisting of noddings originated by rapid falling down of head and bursts of rapid eye movements. EEG activity was like that of waking state. EMG activity was maintained at the same level as during SWS but sometimes it decreased lightly. Total atonie was not observed. Sleep percentages were higher when recordings were done during the nocturnal period.