Local Fidelity Is Key to Humpback Whale Recovery
It is widely known that humpback whales can migrate thousands of miles to reach feeding grounds each year. But, a new study concluded that their fidelity to certain local habitats, passed on through generations of whales, and the protection of these habitats are key to understanding a global recovery of the endangered species.
This study, published in the journal Endangered Species Research, documented the local recruitment of whales in the Glacier Bay and Icy Strait in Alaska over a 30-year period. Researchers found that contemporary whales that utilize these rich feeding grounds were usually descendants of whales that previously used the area. In order words, the population recovery of humpback whales in the Alaskan region depends on cultural knowledge of migratory routes passed on from mothers to their calves. It is not a product of whales from outside the area “discovering” a rich feeding ground.
On a global scale, humpback whales are recovering. But, Scott Backer, associate director of the Marine Mammal Institute of Oregon State University and co-author, says “ultimately, their individual success is on a much more local scale. Humpback whales travel globally, but thrive locally.”
In the study, scientists kept records of all individual whales returning to Glacier Bay, dating from the 1970s of what is considered the “founder’s population”. They include whales documented by a local high school teacher, Charles Jurasz. He was one of the first researchers to realize that individual whales could be identified by photographs of natural markings, a technique now widely used to study living whales.
Over the years, other researchers, including the authors of this study, continued to record the return of these whales by photo identification. Later, they collected genetic samples to confirm the relatedness between individual whales.
The large database was maintained by Glacier Bay National Park and the University of Alaska Southeast with the records of the founding population compared to records of the contemporary population. Of the 25 “founding females” that were also sampled for genetic analysis, all but one was represented in the contemporary group as a direct descendant and still alive. Several of the founding females were even grandmothers of individuals in the contemporary population.
Lead author Sophie P. Pierszalowski, a master’s student in OSU’s Department of Fisheries and Wildlife argues that:. “It is clear that the contemporary generation of whales is based on local recruitment, highlighting the importance of protecting local habitat for recovering species, especially those with culturally inherited migratory destinations.”
Before commercial whaling took a toll, North Pacific humpback whales were once estimated to more than 15,000 individuals based on catch data. However, by 1966, the population was reduced to less than a thousand. In 1965, the species was first protected by the International Whaling Commission and in 1973, it was listed under the U.S. Endangered Species Act.
Since the protection, the global population has estimated to 21,000 individuals based on photo-identification studies and other evidence. Recovery is driven primarily by local fidelity and recruitment.
Study Describes the Mangrove Finch as a “Slow Motion Extinction”
One of the Charles Darwin’s fabled finch species, the mangrove finch is slowly disappearing despite the efforts of conservationists and scientists in the Galapagos Islands working desperately to save it. Plagued by invasive species for decades, the finches have completely vanished from the Fernandina Island. Only one small population of 80 to 100 birds on the west coast of Santa Isabel Island.
This “slow-motion extinction,” as this newly published paper puts it, reveals that the invasive species had a lasting after-effect: the mangrove finches on Santa Isabel Island now have half of the genetic diversity that they had a century ago.
However, this news was actually expected. University of Cincinnati lead author Lucinda Lawson says that “we weren’t particularly surprised by the low level of current genetic diversity, knowing that the last remaining population has been at critically low population size for quite some time, and nearly decimated by the rats and flies”.
In addition, the researchers also discovered something else in their genetic tests. Apparently, the mangrove finches have been breeding and hybridizing with another species, the woodpecker finch. Both species share an overlapping range and look remarkably alike. Other than the males’ different breast colors and songs, they are almost impossible to tell apart.
Scientists have known that hybridization occurs after capturing a few individuals with traits of each species. But, Lawson states they were surprised by the number of hybrids they had found. And the genetics indicate that they have been breeding for at least two generations.
Furthermore, when they investigated a nest of chicks being reared by a mangrove finch father expecting mangrove finch chicks, they found unrelated woodpecker finches.
“To purely speculate on the situation, it’s possible that the female was a woodpecker finch who shared a nest with a male mangrove finch, yet was involved in extra-pair paternity with a woodpecker finch, so the pure woodpecker babies raised by a mangrove ‘father,’” Lawson says. “It’s only one small story within the larger dataset, but it’s an interesting anecdote when evaluating mating within a ‘dying’ population.”
Usually hybridization results in sterile or unhealthy young, but Lawson notes that it probably isn’t hurting the chicks of these two finch species. It is likely due to their being closely related with very small differences between the two.
This hybridization may have occurred to give the mangrove and woodpecker finches an advantage over the parasitic fly, Philornis downsi. Other research has shown that hybrid nests have fewer flies, possibly having gained a specialization that they could use to defend themselves.
Despite the “slow-motion extinction”, Lawson has hope that the mangrove finches can rebound.
“Other bird species have bounced back from near extinction, and there’s no reason to think that these couldn’t as well if their immediate threats are kept in check,” she says, noting in particular the efforts of the Charles Darwin Foundation to control P. downsi levels. “It seems to me that if they can get the flies under control—which they are making some progress on—and keep the rats away, then they may be able to maintain this species and possible see the population grow.”
On the other hand, if the mangrove finch continues to hybridize and “absorbed” by its related species, Lawson argues that it should not “be seen as a particularly negative outcome”.
Major Step Forward: U.S. Hunters Banned from Importing Trophies from Captive Lions
Every year, some 8,000 lions are bred for the sole purpose of being hunted on game ranches in South Africa. With conditions of being confined in small spaces, this practice of canned lion hunting is considered cruel and unrelated to conservation by experts. Every year, thousands of hunters, mostly Americans, pay handsomely to kill these lions.
But now, these hunters will be no longer be able to bring back the heads, skins, claws, teeth, and other lion parts from these kills. On Thursday, the U.S. Fish and Wildlife Service (FWS) banned the import of trophies taken from captive-bred lions in South Africa.
December 2015, the U.S. FWS listed the African lion under the Endangered Species Act, which adds protections and regulations on the import of live lions and trophies into the country. These new permitting requirements give countries with lion populations a “powerful new incentive to work with [the U.S.] to implement sustainable, scientifically sound management strategies,” wrote Dan Ashe, director of U.S. FWS, in a Huffington Post blog.
“Beginning today, the United States will not allow the import of lion trophies taken from captive lion populations in South Africa. While U.S. law has not prohibited such imports in the past, the protections now afforded to lions by the ESA do not allow us to issue import permits.”
Now, to permit the import of lion trophies, exporting nations like South Africa “must provide clear evidence showing a demonstrable conservation benefit to the long-term survival of the species in the wild”. FWS hopes that the decision will substantially reduce the total number of lion trophy imports to the U.S. as the vast majority in the recent years have been from these captive populations in South Africa.
“This is huge,” comments Ian Michler, a conservationist and the narrator of Blood Lions, a documentary released last year that exposed the canned lion industry. “If we can start seriously clamping down on the demand side, then it will impact things here in south Africa.”
After Blood Lions premiered, Australia and France banned the import of captive and wild lion trophies. South Africa’s hunting association, which long had sided with the canned hunting industry, also voted to disassociate itself from the industry.
The new import rules followed the vote at the CITES meeting that gave wildl ions new protections from international trade, but failed to extend them to captive-bred lions. CITES new protections still allow wild lions to be hunted, but it is illegal to buy and sell their bones, teeth, and claws.
The U.S. Fish and Wildlife Service will continue to allow the import of some trophies from wild lions because “scientifically sound conservation programs that include sport hunting of wild lions can significantly contribute to the long-term survival of lions”.
However, the import permits must reflect whether a trophy is from a wild or captive-bred lion. If inspectors have any doubts, they are to reach out to their counterparts in South Africa to confirm. This is to ensure that trophies “from any nation whose lion conservation program fails to meet key criteria for transparency, scientific management, and effectiveness” will not enter the United States.