Climate change is affecting when grey seals give birth, scientists say

Scientists are continuing to discover ways in which climate change is already affecting animal species around the world -- including how it's changing the phenology, or timing of biological events.

Grey seals are the latest species to see phenological shifts due to warming ocean waters, a new study published Tuesday in the Royal Society Journals has found.

Researchers who monitored grey seals in the U.K.'s Skomer Marine Conservation Zone for three decades found that climate change has caused older seal mothers to give birth to pups earlier, an observation that favors the hypothesis that climate affects phenology by altering the age profile of the population.

When the researchers first began surveying grey seals in 1992, the midpoint of the pupping season was the first week of October. By 2004, the pupping season had advanced three weeks earlier, to mid-September, according to the study.

Warmer years were also associated with an older average age of mothers, the scientists found. Grey seals typically start breeding around 5 years old and can continue for several decades after. But the older the seals got, the earlier they gave birth, the researchers said.

The changes were not isolated to the U.K. There have been observable changes in the timing of seal life throughout the Atlantic and the world, according to the study.

Climate change has also recently been linked to a rising divorce rate in albatross couples, which mate for life, and to the shrinking of dozens of species of Amazonian birds, which are evolving to have smaller bodies and longer wing spans.

The causes and consequences of phenological shifts across ecosystems and geographical regions as a result of climate change have become a major area of interest in recent years, according to the study.

These changes can have a domino effect. Since species do not live in isolation, phenological changes can cascade through biological communities through trophic, competitive and mutualistic interactions, according to the study. This can be especially apparent in "mismatches in seasonal events," such as the those between predator and prey populations or flowering plants and their pollinators.

Eventually, phenological shifts in life-history events, such as breeding and pupping, can decouple biological communities and lead to critical transitions in population structure and even the collapse of ecosystems, the scientists said.