Cumulative metallicity distributions of GRB-SN and SN Ic-BL samples: SNe Ic-BL without GRBs on average prefer environments with higher metallicities (see discussion in Sect. 4). For SNe Ic-BL, we plot the distribution including all hosts with metallicities in Table 4 (full line) and the distribution including only the hosts studied in this paper (dashed). Upper and lower plots: metallicities measured using the calibrations of (Pettini & Pagel 2004; O3N2) and (Maiolino et al. 2008; M08), respectively. For comparison, we also plot the distribution of the z < 1 sample of long GRB host galaxies (Krühler et al. 2015; Japelj et al. 2016a) and the samples of SN Ib and Ic host galaxies from Sanders et al. (2012) and Modjaz et al. (2011). The vertical dashed lines indicate solar oxygen abundance of 12 + log(O/H) = 8.69 (Asplund et al. 2009).