Despite our re-visitation of winter last week, many of our migrating songbirds have arrived. Even through snow and cold, they have been quite busy doing all those things birds do in spring. If they have seemed unusually noisy recently, there may be several reasons for that.
First of all, songbirds are notoriously noisy during mating season, what with marking territory and finding mates and all. But in the days following the snowstorm, with snow covering the ground, some of the noisiness was likely due to a natural amplification.
Cold air is a more efficient medium for sound waves. Also, snow on the ground causes a temperature inversion which acts to reflect sound waves back to the ground. Finally, the snow itself absorbs some of the quieter sounds, allowing the noisy chirping to be even more noticeable.