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An unresolved question in galaxy evolution is whether the star formation histories of low mass systems are preferentially dominated by starbursts or modes that are more quiescent and continuous. Here, we quantify the prevalence of global starbursts in dwarf galaxies at the present epoch, and infer their characteristic durations and amplitudes. The analysis is based on the Hα component of the 11 Mpc Hα UV Galaxy Survey (11HUGS), which is providing Hα and GALEX UV imaging for an approximately volume-limited sample of ∼300 starforming galaxies within 11 Mpc. We first examine the completeness properties of the sample, and then directly tally the number of bursting dwarfs and compute the fraction of star formation that is concentrated in such systems. To identify starbursting dwarfs, we use an integrated Hα EW threshold of 100˚A, which corresponds to a stellar birthrate of ∼2.5, and also explore the use of empirical starburst definitions based on σ-thresholds of the observed logarithmic EW distributions. Our results are robust to the exact choice of the threshold, and are consistent with a picture where dwarfs that are currently experiencing massive global bursts are just the ∼6 % tip of a low-mass galaxy iceberg. Moreover, bursts are only responsible for about a quarter of the total star formation in the overall dwarf population, so the majority of stars in low-mass systems are not formed in this mode today. Spirals and irregulars devoid of Hα emission are rare,
Lee et al. (Fri,) studied this question.