抄録
An increase in the number of breeding attempts per year by Tree Sparrows Passer montanus in urban areas has been suggested as one of the factors contributing to the increase in its population in urban environments. To test this hypothesis, I compared the results of a sparrow survey conducted in central Japan in 2010 with those of a field survey conducted in 2025. In rural areas, there was no significant difference in the number of breeding attempts per year between 2010 and 2025; however, in urban areas, the number was significantly higher in 2025. The breeding season of the Tree Sparrow began earlier in 2025 than in 2010, suggesting that the longer breeding season resulting from an earlier onset of breeding may have contributed to the increase in breeding frequency. In addition, green spaces has expanded in urban areas, and improved feeding conditions may also have contributed to the increase in breeding frequency. Urban Tree Sparrows breed significantly more frequently than rural populations, possibly due in part to lower breeding success in rural areas where predators are more abundant.
https://ror.org/0162y3f52 