Tropical bird species tend to produce smaller clutches of eggs than temperate bird species. One hypothesis put forward to explain the difference in clutch size is that the time available for gathering food differs between tropical and temperate species. Another hypothesis is that tropical and temperate species have different strategies that affect the quality and overall robustness of individual nestlings. Match each piece of evidence with the hypothesis that it supports. 1. Food-gathering time influences clutch size
2. Quality of each nestling influences clutch size

a. Tropical nestlings develop longer flight feathers and are better fliers when they leave the nest than temperate nestlings.
b. Temperate bird species make more foraging trips per day than tropical bird species.
c. Tropical bird species do not gather food at a faster rate than temperate bird species.
d. Temperate bird species have lower survival rates as adults than tropical bird species.
e. Bird species from both regions can usually at least provide enough food to keep the nestlings in their clutch from starving.
f. Tropical bird species make more foraging trips per nestling than temperate bird species.