This hybrid background might explain the high fertility of the breed.

Each year the river brings fertile silt which may be responsible for high fertility of the area.

They are prolific and with high fertility controlled by environmental conditions.

Due to its high fertility Oahu became the most important of the islands.

Farming has always been present in the area, due to the high fertility of the soil.

It cited high fertility and immigration rates among Hispanic people.

Owing to the high fertility, 70% of Russian cereal production in the 1850s was here.

Under some circumstances high fertility may be rational (Caldwell 1982).

But the growth of these areas was also substantially due to their higher fertility (see Chapter 9).

Dual graduate couples have the highest fertility of all, if family size up to four children only is considered.