Although the low densities of resident waterfowl populations and unfavorable environmental conditions may impact virus circulation and epizootic dynamics, our findings showed that California waterfowl and wetlands may serve as a reservoir for AIv. Our findings justify further longer-term investigations about the dynamics of AIv infection in resident waterfowl populations to determine the importance of southern summer waterfowl areas as a potential source of infection for migratory wintering ducks, and to evaluate the potential to enhance virus exchange and favor virus reassortment through mixed infections. Such information is basic for the understanding of AIv epidemiology and ecology. Antimicrobial peptides constitute a broadly defined class of short, cationic peptides produced by virtually all organisms. Since their discovery microbiological methodologies have been employed to characterize their antibacterial action. In turn, the relative simplicity in sequence and secondary structure of AMPs, together with mechanisms that depend largely on membrane interaction, made biophysical methodologies the tools of choice to describe the molecular level action of AMPs. A gap, however, separates the two distinct approaches: information from biological studies is seldom correlated to the findings on peptide Hexyl Chloroformate behavior at the molecular level. Threshold behavior is a point where the two fields come together. On one hand, the activity of an AMP is commonly expressed as the threshold concentration upon which bacterial growth is inhibited. On the other, biophysical studies with model phospholipid membranes often identify concentration thresholds upon which the peptide behavior becomes disruptive �Ctipically through pore formation or membrane lysis. This is an expected point of convergence between biological activity and molecular-level behavior given that the bacterial membrane has long been identified as the primary target for most AMPs; indeed, connections between in vivo MICs and thresholds in model membranes have been recently proposed. In this work we describe a simple physical-chemical framework that models this correlation. We then fully explore its predictive power, with good predictions for the activities of the AMPs Omiganan and BP100. Our analysis is centered on the comparison of local membrane 2-Hydroxypropyl-BETA-cyclodextrin concentrations at the threshold events of the MIC and of molecular-level membrane disruption. It therefore requires that those concentrations be known or somehow estimated. The high obtained concentration also supports the proposed view that, rather than being unphysiological, such high bound AMP concentrations are expectable events in vivo. Furthermore, because the MIC estimate only depends on the intercept of the curve, the prediction is robust to the actual lipid concentrations as long as relative dilutions between data points are kept.