Question

8. (3pts) Parents are often trying to maximize their lifetime reproductive success. In general, which types of birds (northern vs southern) are more likely to put themselves at risk in order to protect their nestlings (1 point) :

and why? (2 pts)

Answer 1

Parental care refers to the level of investment provided by the mother and the father to ensure development and survival of their offspring. In most birds, parents invest profoundly in their offspring as a mutual effort, making a majority of them socially monogamous for the duration of the breeding season. This happens regardless of whether there is a paternal uncertainty.

Parental care is any form of investment made by a parent that increases an offspring's rate of survival (reproductive success) at the expense of the parent or parent's ability to divert investment towards a new brood. The cost must yield sufficient benefits to ensure current and future breed survival. If parents invest too much parental care into the current brood their future brood will be at risk or cease to exist entirely. An ideal level of parental investment that will ensure the survival and optimal quality of both broods exists. In most bird species, females invest in parental care more than males at the expense of reproductive success.

Northern versus Southern types of Birds:-

(1) A hypothesis was tested in South America to see if species of birds would respond more aggressively to an adult predator (a hawk) than their Northern counterparts because they care more about future reproductive success due to a smaller brood size. On the other hand, those in North America respond more aggressively to an offspring predator (a jay) because they care more about their current brood due to a larger brood size.

(2) Often parents change the level of parental care provided to manage the cost and benefits of parental care. Passerine species in North America have a large brood size containing 4–6 offspring and a 50% adult survival rate, and those in South America have a smaller brood size containing 2–3 offspring and a 75% adult survival rate. An increase in parental investment (shown by the number of trips made) also increases the threat of predation.

so southern types of birds put themselves at risk to protect their nestlings.