Though robins are one of the most common birds in the country with one of the most recognizable and easy-to-spot nests, they are actually very picky about nesting conditions—not so much about placement (hence nests found in door wreaths and outdoor light fixtures), but weather. Robins often lay three broods a year, but only when the temperature and humidity are just right. A study of 8,500 robin nests across the US showed that they lay eggs when the average noon temperature is 45-65 degrees and noon humidity is right around 50%. Otherwise they will hold off laying eggs until conditions are met!