  We present results of a Hubble Space Telescope (HST) UBVI-band study of star
clusters in tidal tails, using new WFC3 and ACS imaging to complement existing
WFPC2 data. We survey 12 tidal tails across seven merging systems, deriving
ages and masses for 425 star cluster candidates (SCCs). The stacked mass
distribution across all systems follows a power law of the form $dN/dM \propto
M^{\beta}$, with $\beta = -2.02 \pm 0.15$, consistent with what is seen in
other star forming environments. GALEX and Swift UV imaging provide star
formation rates (SFRs) for our tidal tails, which when compared with ages and
masses of our SCCs, allows for a determination of the cluster formation
efficiency (CFE). We find the CFE increases with increasing SFR surface
density, matching the theoretical model. We confirm this fit down at SFR
densities lower than previously measured (log $\Sigma_\text{SFR} \:
(\text{M}_\odot \: \text{yr}^{-1} \: \text{kpc}^{-2}) \approx -4.2$), as
related to the CFE. We determine the half-light radii for a refined sample of
57 SCCs with our HST WFC3 and ACS imaging, and calculate their dynamical age,
finding the majority of them to be gravitationally bound. We also provide
evidence of only low-mass ($< 10^4 \: \text{M}_\odot$) cluster formation in our
nearest galaxy, NGC 1487, consistent with the theory that this system is a
dwarf merger.
