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<div><p>The common house mosquito <i>Culex pipiens</i> s.l., widely distributed in Europe, Africa, and North America has two recognized biotypes, <i>Cx</i>. <i>pipiens</i> biotype <i>pipiens</i> and <i>Cx</i>. <i>pipiens</i> biotype <i>molestus</i>, which hybridize. Despite their morphological similarities, these biotypes may exhibit ecological differences. This complex ecological mosaic may affect the interaction of <i>Cx</i>. <i>pipiens</i> with pathogens like avian <i>Plasmodium</i>, which is transmitted to wildlife. Although the vector competence for <i>Cx</i>. <i>pipiens</i> biotype <i>molestus</i> has been well studied, there is a lack of studies comparing the vector competence of <i>Cx</i>. <i>pipiens</i> biotype <i>pipiens</i> and their hybrids for the transmission of avian <i>Plasmodium</i>. Here, we evaluated the vector competence of the <i>Cx</i>. <i>pipiens</i> biotypes <i>pipiens</i>, <i>molestus</i> and their hybrids for the transmission of two avian <i>Plasmodium</i> species. Mosquitoes were allowed to feed on blood of wild infected birds and the presence of DNA of <i>Plasmodium</i> in head-thorax and saliva of mosquitoes was molecularly evaluated at 13 day-post exposure. The transmission rates (i.e., the detection of parasite DNA in mosquito saliva) for <i>Plasmodium cathemerium</i> were similar for the two biotypes of <i>Cx</i>. <i>pipiens</i> and their hybrids while <i>Plasmodium relictum</i> DNA was only found in the saliva of <i>Cx</i>. <i>pipiens</i> biotype <i>pipiens</i>. In addition, <i>P</i>. <i>cathemerium</i> was significantly more prevalent than <i>P</i>. <i>relictum</i> in the saliva of <i>Cx</i>. <i>pipiens</i> biotype <i>pipiens</i>. Our results suggest that avian <i>Plasmodium</i> is transmitted by both <i>Cx</i>. <i>pipiens</i> biotypes and their hybrids although differences could be found depending of the parasite species studied. Differences in the abundance of each biotype and their hybrids within areas characterized by distinct environmental conditions, along with variations in their blood-feeding patterns and the parasites infecting birds, could ultimately determine differences in the relevance of each <i>Cx</i>. <i>pipiens</i> biotype in the transmission of avian <i>Plasmodium</i>.</p></div>