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Manatees are not Florida natives

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Florida is very proud of its manatees.  It has a county named after them and has pictures of them on license plates.  These gentle creatures are part of Florida culture.  But recent research indicates that manatees – also known as sea cows – might only be relatively recent residents of the Sunshine State.

Manatees have been spotted in Florida waters for several centuries but might have only been tourists visiting briefly before returning to their home waters in the Caribbean in places like Cuba.

The new research suggests that manatees might not have actually taken up residence in Florida until after Europeans colonized the area in the 1500s.  There is a rarity of manatee bones on archaeological sites that date back further.  It was particularly striking that Crystal River, which is an epicenter for modern manatee populations, had little evidence of their presence in earlier times.

Even into the early 1900s, Florida newspaper reports treated manatee sightings as a spectacle rather than a common occurrence.  In the 1920s and 1930s, there started to be more routine sightings in places like yacht basins and canal harbors.  In the 1950s, manatees became more plentiful in Tampa Bay and Crystal River. The warming waters and human activities creating shallow warm water refuges increased manatee populations, particularly near places like power plants.

The current Florida manatee population is between 8,000 and 12,000 and is classified as threatened under the Endangered Species Act, an improvement over its previous endangered status.  But pollution is killing a lot of the seagrass that they eat, and their safety is by no means assured.

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Why manatees are likely not Florida natives

Photo, posted March 25, 2012, courtesy of David Hinkel / USFWS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Rainfall and sea turtles

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There are seven species of sea turtles that inhabit the world’s oceans. Six of the seven sea turtle species – all of them except the flatback – are present in U.S. waters, and are listed as threatened or endangered under the Endangered Species Act. 

Sea turtles, which have been around for more than 100 million years, spend the majority of their lives in the ocean, but they do periodically come ashore to nest.  Female sea turtles lay their eggs in the sand and then return to the ocean.  Survival odds for sea turtle hatchlings are quite bleak.  In fact, only one out of every 1,000 makes it to adulthood. 

Research shows that both air and sand temperatures are critical for sea turtle hatchling development.  Cooler temperatures produce larger, heavier hatchlings with more males.  Hatchling size matters because larger hatchlings, which can move faster, are more likely to survive because they spend less time on risky beaches.  But rising temperatures might shorten incubation periods, and erratic rainfall can disrupt growth, potentially affecting survival.

A new international study by researchers from Florida Atlantic University and the University of Tübingen in Germany found that fluctuating rainfall patterns have a greater impact than changes in air temperature on sea turtle hatchling development. 

The results, which were recently published in the journal BMC Ecology and Evolution, reveal that the impact of rainfall varies between species.  As climate change shifts rainfall patterns, the impact on sea turtle nesting sites suggests that global conservation strategies for some species – like loggerhead and green sea turtles – likely need to be updated.

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Rain or Shine? How Rainfall Impacts Size of Sea Turtle Hatchlings

Sea Turtle

Photo, posted August 27, 2015, courtesy of USFWS/Orsulak via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Confusion about monarch butterflies

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For years, we have heard that the iconic monarch butterfly is in great peril.  Monarchs east of the Rocky Mountains undertake a 4-generation, 3,000-mile migration in late summer to their winter home in central Mexico.  Since the 1990s, the overwintering monarch colonies began a steep decline causing scientists to fear for the sustainability of the species.  Trying to help, ordinary citizens have been planting milkweed – the food for the caterpillars – and have been rearing eggs and caterpillars on their porches and releasing adult butterflies.

A number of recent studies have rocked the world of monarch science.  A growing group of scientists now believe that monarchs are not in fact imperiled and that the home rearing and commercial breeding of monarchs is actually a major threat to the butterfly.

According to a comprehensive 2022 study, there has been no sharp decline in Eastern monarch populations across their summer breeding range.  The long-term declines in winter colony sizes are real but do not appear to be affecting the collective breeding population of Eastern monarchs. 

An undisputed major threat to monarchs is a parasite known as OE, which weakens butterflies and also makes it unlikely for them to complete migrations.  It turns out that overcrowding of butterflies resulting from the efforts of backyard and commercial breeders is increasing the spread of the disease.  The butterflies are in need of social distancing.

Monarch scientists are split into two camps.  One group calls for the protection of the butterfly under the Endangered Species Act.  The other says that what monarchs most need is for us to leave them alone.  It is a confusing situation.

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Rethinking Monarchs: Does the Beloved Butterfly Need Our Help?

Photo, posted October 1, 2021, courtesy of Renee Grayson via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Lots of female turtles

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Green sea turtles were listed under the Endangered Species Act in 1978.  Since that time, there have been conservation measures put in place in many locations.  One such place is Florida, where restrictions on beachfront development and careful monitoring of turtle nests has helped to get hatchlings safely into the water.  A gill net ban in 1995 sharply reduced the number of young turtles killed by fishing gear.

All of this has resulted in what is described as an explosion in turtle populations in Florida.  Volunteers monitoring the 2023 nesting season on Florida’s beaches have counted more than 74,000 nests.  That beats the previous record – set in 2017 – by an incredible 40%.

Unfortunately, this does not represent a guaranteed great future for the species.  Sea turtles are particularly sensitive to the warming climate.  The sex of a baby sea turtle is not determined by DNA, but rather by the temperature of the sand in which its egg develops.  Cooler temperatures mean more males; warmer ones mean more females.

In recent years, the proportion of male green sea turtles has dwindled substantially.  In the past few seasons, between 87 percent and 100 percent of the hatchlings tested in Florida have been female.

In the short term, the skewed sex ratio might be a boon for the species.  Lots of females laying lots of eggs means lots of turtles.  Sea turtles don’t reach sexual maturity until their twenties or thirties.  So, for the next few decades, there are likely to be growing numbers of turtle nests.  But down the line, there is going to be a real problem.  Where will for all the female turtles find the mates to populate the species in the future?

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Florida Turtle Nests Are Recovering. When They Hatch, Expect Mostly Girls.

Photo, posted October 5, 2011, courtesy of Keenan Adams / USFWS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Chasing The Ivory-Billed Woodpecker | Earth Wise

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The ivory-billed woodpecker is or was the largest woodpecker in the United States. The last unassailable sighting of the bird was in 1944.  Since then, there have various reports of glimpses of the bird or of hearing its distinctive sounds.  But there has not been anything resembling proof that the bird still exists.

Despite this, the ivory-billed woodpecker has been legally protected under the Endangered Species Act.  There has been a proposal to end that protection and formally declare the species extinct.  Because of the controversy surrounding the bird, a final ruling on its status has been repeatedly delayed by the US Fish and Wildlife Service.

Very recently, a peer-reviewed study in the journal Ecology and Evolution makes the case that the ivory-billed woodpecker still exists and that it is premature to declare it extinct.  The study cites visual encounters by expert observers, audio recordings, tree-damage, and rather grainy video evidence.  The authors claim that there is intermittent but repeated presence of birds that at least look and behave like ivory-billed woodpeckers.

One might ask:  why does it matter whether this bird is declared extinct or not?  The answer is that there are limited federal funds for conservation efforts, and they should be spent on saving genuinely endangered species and habitats.  The authors of the new study say that removing federal protection would be bad for any remaining ivory bills, which may be living in some swampy old-growth forests in Louisiana.  Other scientists consider conservation resources expended on the ivory-billed woodpecker to be chasing a ghost.

As is the case for several other notorious objects, one really clear photograph of an ivory-billed woodpecker could solve a long-standing mystery.

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A Vanished Bird Might Live On, or Not. The Video Is Grainy

Photo, posted October 19, 2014, courtesy of James St. John via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Manatees And Pollution | Earth Wise

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Manatees are large, gentle, and curious marine mammals measuring up to 13 feet long and weighing up to 3,300 lbs.  There are three living species of manatees:  The Amazonian Manatee, the West African Manatee, and the West Indian Manatee, which is commonly found in Florida and the Gulf Coast.  Manatees inhabit the shallow, marshy coastal areas and rivers of the Caribbean Sea, the Gulf of Mexico, the Atlantic coast, the Amazon basin, and West Africa. 

The West Indian Manatee, which includes the Florida Manatee, is protected under the Endangered Species Act.  Today, the range-wide population is estimated to be at least 13,000 manatees, with more than 6,500 in the southeastern United States and Puerto Rico.

In Florida, an uptick in nutrient loading from nonpoint sources is triggering algal blooms in Indian River Lagoon and neighboring areas.  These algal blooms have decimated seagrass, manatees’ primary food source. 

As a result , manatees have starved to death by the hundreds along Florida’s east coast.  The state has recorded 974 manatee deaths in 2021, shattering previous annual all-time highs with still approximately two months to go.  Manatees, which need to eat between 100-200 pounds of seagrass daily, are now eating the seagrass roots, which permanently kills the aquatic plants.

Efforts are being made to replant seagrass and to restore clam and oyster beds so that the mollusks can help clean the water.  But manatees face a myriad of additional threats, including collisions with boats and ships, temperature changes, disease, and crocodile predation.

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Florida lawmakers hear Fish & Wildlife agency response to manatee death ‘catastrophe’

West Indian manatee

Preliminary 2021 Manatee Mortality Table by County

Photo, posted May 7, 2010, courtesy of Jim Reid/USFWS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

What Is An Endangered Species? | Earth Wise

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Biodiversity is declining rapidly throughout the world and people are mostly the reason.  Species are disappearing because of changes in land and sea use, the direct exploitation of organisms, climate change, pollution, and invasive alien species resulting from globalization.  The challenges of conserving the world’s species are many and difficult.  Among these challenges are determining which species are endangered and how and when to protect them.

What constitutes an endangered species is not necessarily obvious. 

Extinction risk increases as a species is driven to extinction from portions of its natural range.  Most mammal species have already been driven to extinction from half or more of their historic ranges because of human activities.

According to a recent survey of ordinary Americans, three-quarters of participants said that a species deserves special protections if it had been driven to extinction from any more than 30% of its historic range.  This compares with the language of the U.S. Endangered Species Act that defines an endangered species as one that is “in danger of extinction throughout all or a significant portion of its range.”

Experts and decision-makers are more accepting of risks and losses because they believe greater protection would be impossibly expensive.  Decision-makers tend to be influenced by special interest groups with a vested interest in not instituting protections.

Before human activities began elevating extinction risk, a typical vertebrate species would have experienced an extinction risk of 1% over a 10,000-year period.  Current policies consider a 5% risk over 100 years to be acceptable.  Policies consider whether we can afford to protect species.  Given the dangers of declining biodiversity, we should ask whether we can afford not to.

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What Is An Endangered Species?

Photo, posted July 29, 2018, courtesy of Sergio Boscaino via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Is The World’s Largest Sea Turtle No Longer Endangered?

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The rapid disappearance of many plants and animals around the world has many scientists saying we are experiencing a sixth mass extinction – the first since the dinosaurs were wiped out some 66 million years ago.  Despite all sorts of conservation efforts, living things are struggling as a result of climate change, habitat loss, and countless other natural and manmade pressures.  Conservation success stories have been few and far between. 

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Sea Turtle Populations Are Rebounding

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The increasing disappearance of so many plants and animals around the world has made many scientists believe that we are experiencing a sixth mass extinction.  Despite ongoing conservation efforts, living things are struggling with habitat loss, climate change, and many other natural and man-made pressures.  Conservation success stories seem to be rare events.

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Endangered Bees

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It’s no secret that pollinators around the world are under threat.  According to a U.N. sponsored report released earlier this year, 40% of invertebrate pollinator species, such as bees and butterflies, are facing extinction.  And since approximately 75% of the world’s food crops depend on pollination, the decline of these pollinators poses a major threat to food worldwide. 

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