This means some animals have started turning up in places they were never seen before. In recent years, Asian tiger mosquitoes have spread throughout the southern half of the United States, and research has suggested that global warming will enable the population to expand further north in the coming decades. Declining quino checkerspot butterflies, found in Mexico and California, amazed scientists in the last few years by rapidly shifting their range to higher altitudes to escape increasingly hot and dry conditions in their ancestral habitats. And several studies have indicated that many fish species are gradually making their way north to cooler waters.
While climate change is definitely wreaking havoc on Earth’s ecosystems in ways that we’re just starting to understand, that doesn’t mean that every wayward animal is definitely being driven by rising temperatures and other climate-related effects. Sometimes animals turn up in crazy places — and if they’re traveling alone and it’s a relatively isolated event, the explanation could be much simpler.
Simple curiosity can be enough to drive some animals out of their normal ranges. Just last week, a Florida manatee was spotted in Delaware swimming through a canal near the Chesapeake Bay. Since manatees usually don’t venture much further north than the Carolinas, the sighting attracted national attention and invited discussion on what could have caused the animal’s behavior.
But while it might be tempting to speculate that climate-related warming waters or changes in ocean currents might have drawn the manatee so far up the coast, the incident may have simply been the result of the animal’s curiosity or wanderlust, says Katie Tripp, director of science and conservation at Save the Manatee Club.
“Like people have different personalities, manatees do too, and some seem to have the traveling and exploring bug,” she says. Furthermore, while the behavior is unusual, it’s not shocking: Another manatee (or possibly the same one) was spotted in the Chesapeake Bay several weeks ago, and Tripp says every year a few end up swimming a little further north than the rest of their population.
And, she adds, “There are more manatees than there used to be. It’s possible that if you have more that the odds would say that you get more of these curious type individuals that would head north.”
Population increases may be able to explain the strange behavior of other wildlife, too. Last month, fishermen in Kenya’s Kiunga Marine National Reserve got a shock when they snagged an unexpected critter in one of their nets: an adult subantarctic fur seal, an animal usually found thousands of miles further south.
On June 23, the fishermen hauled their unlikely catch to shore, where conservationists helped identify it before releasing it back out to sea. According to George Maina, a marine project coordinator with The Nature Conservancy in Kenya, “The local people were so excited to see this new animal, they held a quick blessing ceremony before releasing it unharmed.”
It’s an exciting and unusual event — more unusual than the manatee sighting — but one that’s not altogether unprecedented. Subantarctic fur seals occasionally turn up far outside of their normal ranges. The seals usually hang out in the southern parts of the Atlantic, Pacific and Indian oceans and breed on islands in or around the Southern Ocean, which surrounds Antarctica. But “vagrants” have been known to appear in southern Africa and South America, as well as Australia, New Zealand and Madagascar.
These events have occurred several times in the past decade. In 2008, a young subantarctic fur seal was captured on Unguja Island in Tanzania’s Zanzibar Archipelago. And in 2010, another seal was spotted in Mayumba National Park in Gabon, an event that, at the time, was described as the northernmost sighting of the species so far. The Nature Conservancy claims that the new sighting in Kenya is more than 100 miles further north than any previous sighting.
Some experts believe the seal’s strange behavior could have been caused by expanding seal populations further south. In the late 19th and early 20th centuries, the fur seals were hunted nearly to extinction, says Greg Hofmeyr, a seal researcher with Port Elizabeth Museum in South Africa. Populations have been increasing since then, and while the seals are not experiencing overpopulation, they might be “approaching carrying capacity at some sites,” Hofmeyr told the Post by email.
Since more seals are present, “more will be likely to be found further afield,” Hofmeyr added. “Also with less breeding habitat available, it is possible that the younger, and therefore the likely inherently more exploratory seals, are searching further afield.” In other words, the fact that there are more seals around naturally increases the likelihood that some of them will venture out and wind up by chance in strange places like Kenya.
That said, climate change was a tempting explanation in both the case of the manatee and the seal. According to Tripp, with Save the Manatees Club, climate-related changes in the waters off the East Coast, such as rising water levels in some places, could still be causing changes in manatee behavior — but it’s hard to say for sure from just a few isolated incidents.
And in his blog post about the wandering fur seal, Maina (with The Nature Conservancy) suggested that warming waters in the Southern Ocean could also have driven the seal to explore new territory.
“The Kiunga Marine National Reserve, where the [seal] was caught, is positioned near a colder Somali Current,” Maina wrote. “This current may have led him north with an abundant supply of food and probably some relief from the warmer surrounding waters.” However, Hofmeyr says he doubts climate change had much to do with this seal’s behavior — and Marthán Bester, a seal expert at the University of Pretoria in South Africa, agrees.
“They forage in colder water, so with climate change … it would be more profitable to forage further to the south from their usual range,” Bester wrote in an email. He also added that only a few individuals have been observed straggling so far out their range — not enough to establish a trend in their behavior. The seal discovered in Kenya could have simply ventured a little further out usual and gotten lost, Bester suggested.
If large groups of animals start changing their behavior together over a period of time, that could be the indication of a trend, maybe caused by climate or maybe by some other environmental influence. The world is, indeed, a changing place, and climate change is one of the biggest causes. Temperatures are rising, weather patterns are changing, ocean currents are shifting and many species are already adjusting their ranges as they try to stay within the climate conditions that best suit them.
But if one curious animal ventures out of its comfort zone, we can’t always interpret it as a sign of something bigger. In many cases, like that of the manatee and the seal, it’s probably better chalked up to a freak incident — not necessarily cause for alarm, but a rare but exciting event for scientists and wildlife enthusiasts nonetheless.