Survival
In adult House Sparrows, annual survival is 45-65%. After fledging and leaving the care of their parents, young sparrows have a high mortality rate, which lessens as they grow older and more experienced. Only about 20–25% of birds hatched survive to their first breeding season. The oldest known wild House Sparrow lived for nearly two decades; it was found dead 19 years and 9 months after it was ringed in Denmark. The oldest recorded captive House Sparrow lived for 23 years. The typical ratio of males to females in a population is uncertain due to problems in collecting data, but a very slight preponderance of males at all ages is usual.
Read more about this topic: House Sparrow
Famous quotes containing the word survival:
“The planet’s survival has become so uncertain that any effort, any thought that presupposes an assured future amounts to a mad gamble.”
—Elias Canetti (b. 1905)