2024 Firefly Recap

The 2024 firefly season is over, and the results of season 7 show a continuing downward trend. I started monitoring fireflies at my parents' house during the summer of 2018, counting the number of flashes seen in 3 separate 10 second periods. I spaced my observation periods in 10 minute intervals, each with deepening darkness. Season 3, in 2020, was the highest total count with 708 flashes counted. Every season since then has seen totals lower than the previous.

Generally, firefly populations, like other insects, are decreasing. Reasons for this include habitat loss and degradation, pesticide use, and increased light pollution. Of course, local conditions will drive population trends in different areas. What caused my population to decrease is unknown, although cooler than usual spring temperatures could contribute.

From 2022 to 2023, there was a 25% decrease in number of flashes. Naturally, I was very curious as to whether or not the population would rebound in 2024, or even remain steady. Sadly, the numbers got worse. In 2024 the count was only 276, a decrease of another 26% on top of the 2023 decrease. That's a decrease of over 60% of the peak in 2020.

The charts below show firefly activity annually by daily flashes and annually by total flashes per year. You can see peak activity in late June and early July until 2023. 2023 peaked late and 2024 peak. Both years peaked at a rate lower than previous years.

Annual firefly count by day

Annual firefly count by yearly total

Once again, I'm curious to see if the population will rebound or continue to dwindle. However, for personal reasons I'm considering ending my firefly observations, at least at the current location. If I do chose to continue, it will be interesting to see what happens.

I Scream, You Scream, We All Scream for Isoprene

Plants are well known for absorbing carbon dioxide from the atmosphere and replacing it with oxygen as part of the photosynthesis process. But that’s not the only thing they put into the air. Trees emit tons of a chemical known as isoprene every year, mostly during summer months. It’s surprising to learn that plants contribute to air pollution. 

An abundance of isoprene can lead to formation of greater amounts of ozone by combining with nitrogen in the form of NO and NO2. Ozone in higher levels of the atmosphere is good because it blocks harmful UV rays from the sun, but at our level it’s a major pollutant.  

The current theory is that plants produce isoprene as a method of heat resistance. Like water vapor and oxygen, it is emitted through the pores in a plant’s leaf. Not every plant produces isoprene, but the biggest producers in the US are oaks and poplars.  

Shenandoah National Park (NPS)

Isoprene is what gives the Blue Ridge Mountains their blue appearance. The chemical haze scatters blue light, which makes the mountains appear blue from a distance. It also gives the Smoky Mountains their smoky appearance. 

Great Smoky Mountains (NPS)

We learn such shocking things about nature. I had no idea before today that plants are polluting the air with volatile organic compounds, which when man-made seem to be about the worst thing under the sun. Yet here they are, also giving some of our national parks their distinguishing features and even namesakes. 

Information comes from National Center for Biotechnology Information and Department of Energy Office of Science.

Energy Alternatives

Energy is important at a biological level to sustain life, and at a societal level to sustain lifestyle. From
the discovery of fire to the Nuclear Age, energy consumption has changed over the years, and has also
changed the planet. Use of fossil fuels is largely to blame for an increase of atmospheric carbon dioxide
and accompanying changes in climate. The search for reliable, alternative energy sources leads down
many paths, each with its own strengths and weaknesses. Over the next few weeks, we will examine
several energy sources in an attempt to determine which the “greenest” is.

Before examining the benefits and drawbacks of alternative energies, a look at what they are an
alternative to, fossil fuels- petroleum, coal, and natural gas- is in order. Fossil fuels are still in use
because they are relatively cheap, easily refined, and provide many jobs.

Oil drilling (Bureau of Land Management)

The drawbacks of fossil fuels, in addition to the carbon dioxide output, is other environmental
degradation associated with extraction and transport. Finally, because it is a finite source, eventually
the supply will run out. As supply drops, more invasive techniques will be used to extract ever scarcer
supplies and price will go up.

Environmental impacts of drilling for oil and gas include habitat loss at the well site and access roads; noise pollution; air pollution from generators, vehicles, gas flaring, and particle matter; soil disturbance; increased erosion from vegetation loss; increased solid and industrial wastes; degraded water quality from runoff of soil and residues; and oil spills. There are also problems from end-use: air pollution, increased carbon emissions, contamination such as may be found at gas stations, and plastic litter (most plastics are petroleum-based).

Mountaintop removal coal mine (Center for Biological Diversity)

After all the environmental and health issues related to fossil fuels, it seems clear that we need an alternative energy source. There are plenty of green alternatives, which we will explore, starting with hydroelectric next week.

Herring Spawning

One of the great spectacles in North American wildlife watching is the Pacific herring spawning. It happens every year in late winter and early spring. Not only does the event produce the next generation of an important fish species, it also sustains the current generation of many other animals.

Pacific herring form an important strand in the food web. They are classified as forage fish, meaning they serve as meals for larger fish like salmon. As we'll see a little later, herrings feed the larger community beyond just the salmon.

Herring spawning turns the sea white (Prince William Sound Conservation Center) 

Herring move to shallower seas during spring, which happens to be right around the same time hungry humpback whales arrive from the tropics. The herring are looking for eelgrass or kelp beds for their sticky eggs to attach to. After the females lay their eggs over the vegetation, the males swim over and release their milt to fertilize the eggs.

Before reaching the spawning beds, the herring must navigate a maze of predators: sea lions, sea birds like cormorants and gulls, bald eagles, and those hungry, hungry humpbacks. Once the work is done, the eggs aren't safe and the smorgasbord continues as diving ducks pick them off. About two weeks later, the remaining eggs hatch and the herring larvae are carried by the tide and are subject to predation by fish of all shapes and sizes.

Herring eggs attached to kelp (US Geologic Survey)

With all that eating going on, it's a wonder any herring survive to adulthood. Females typically lay 20,000 eggs a year, and if she lives a long life, she'll do this three times. Multiply her by a million of her closest friends, and you have about 20 billion eggs. If only 1% hatch, that's 200 million baby herring.

Sea lions await their feast (Tillamook Coast)

In a good year, spawning herring will color the sea white. However, the spawning isn't nearly as good as it used to be. Overfishing is one reason, but loss of habitat (spawning and feeding areas) and pollution are also big contributors.
This week's information comes from Wayne Hoffman, Ph.D. and Washington Department of Natural Resources.
nm1: Prince William Sound Conservation Center https://pwssc.org/herring-spawn/
nm2: USGS https://www.usgs.gov/media/images/pacific-herring-eggs-macrophytes
nm3: Wayne Hoffman https://tillamookcoast.com/blog/spawning-of-pacific-herring/

A Breath of Fresh Air

If you like fresh air, you're probably a big fan of the Clean Air Act and its amendments. While the air in many places is far from ideal, prior to federal legislation it was downright deadly in American cities. A clear gray sky on a summer's day in Philadelphia is a little off-putting, but it beats a smothering fog in the valleys outside Pittsburgh. After the deadly Donora smog in 1948 killed 20 and sickened thousands of others. Federal investigators were asked to come in, and determined that air pollution was in fact the killer, among other factors.

Donora smog, 1948 (Smithsonian)

The government prefers to take baby steps when implementing positive change, rather than jumping in feet first, and tackling air pollution is no exception. The first step came in 1955 with the Air Pollution Control Act, which provided funding for research and led to the Clean Air Act of 1963 and Air Quality Act of 1967. These provided the first air quality monitoring.

Pittsburgh in the 1940s (Citylab)

The Clean Air Act of 1970 was a major step forward. It developed limits on pollution and expanded federal enforcement powers. Among the controls included were auto emissions. States were mandated to implement plans to reduce pollution.
The Amendments of 1990 aimed to reduce air pollution linked to acid rain and ozone depletion.
Looking at a picture of the summer sky over Los Angeles, it might be hard to believe the Clean Air Act is working. However, the number of ugly sky days is lower than prior to enactment. Air quality monitors in California frequently show poor quality, and geography is partly to blame. Ocean breezes carry pollution as far as the mountains, where it gets stuck and sometimes builds up for days.

Los Angeles skyline (LAist)

Acid rain has been reduced as a result on the 1990 amendments. pH testing has shown freshwater pH levels in many areas have risen closer to neutral 7. Pure water is neutral, but in nature, water is rarely pure. Pristine rain is slightly acidic because of carbon dioxide in the atmosphere forming carbonic acid. However, the lowered pH in rivers and lakes nationwide was far lower than caused by carbonic acid. Targets of the 1990 amendments were nitrogen oxides (NOx) and sulfur dioxide (SO2). Emissions have been greatly reduced over the last 30 years, and ecosystems are continuing to slowly recover.

Visuals of higher pH meaning less acidic water samples
(National Atmospheric Deposition Program)

Information this week comes the EPA (Clean Air Act overview), Smithsonian Magazine (Donora), and more EPA (acid rain). For a great visual on showing higher pH and lower NOx and SO2, check out the National Atmospheric Deposition Program.

EPA: https://www.epa.gov/clean-air-act-overview/evolution-clean-air-act
Smithsonian: https://www.smithsonianmag.com/history/deadly-donora-smog-1948-spurred-environmental-protection-have-we-forgotten-lesson-180970533/
EPA: https://www.epa.gov/airmarkets/acid-rain-program
nm1 LAist: https://laist.com/2018/10/30/why_las_smog_has_been_extra_smoggy.php
nm2 Citylab: https://www.citylab.com/design/2012/06/what-pittsburgh-looked-when-it-decided-it-had-pollution-problem/2185/
nm3 Smithsonian
nm4 National Atmospheric Deposition Program http://nadp.slh.wisc.edu/data/animaps.aspx

Wisdom of the Ages

While it’s cold and snowy where you are, it’s a warm sunny day on the Pacific atoll of Midway Island, where mating season just ended for the Laysan albatross. Most famous of these large seabirds is Wisdom, the oldest known wild bird. She’s at least 67 years old and still laying eggs. Being that old and still raising young makes me wonder just how long these birds can last.

Wisdom’s age was discovered in 2002 when her band was replaced. The biologist who replaced her band looked up her number and noticed that he originally banded her in 1956, and at that time she was an adult of at least 5 years old.

Wisdom (right) and her mate during nesting season (USFWS)

What is remarkable about this particular bird so special, at least to me, is that she managed to survive so many threats in her time, beyond the normal dangers like predators, disease, and typhoons. Working in her favor are the Migratory Bird Treaty and the US Wildlife Refuge System, protecting her and her kind from human predation and habitat loss at their nesting sites on Midway.

Working against Wisdom and other albatrosses are a whole host of man-made problems. Foremost among them is ocean plastic. Laysan albatrosses feed at night, and their food is fish, squid, and fish eggs that come near the surface. Sadly, floating garbage is also at the surface. In a tragic sequence of events common to marine life everywhere, they mistake plastic for food and either eat it themselves or feed it to their chicks. Despite having full stomachs, the birds and other critters die of starvation because plastic is not very nutritious.

Invasive species are also beginning to take a toll on the albatrosses. They have already been extirpated from the Hawaiian Islands, outcompeted or outright killed by the dogs, cats, pigs, and rats that accompanied Europeans as they traversed the Pacific. Now, the Midway colony is under attack by mice. While the birds are much larger than the mice, they succumb to bite wounds rather move to a mouse-free area because of their dedication to their eggs. US Fish and Wildlife Service is working on eradicating mice from Midway, but having lived with them for thousands of years I think we all know how well that will work out.

Mouse attack victim (Audubon)

This week's information comes from the US Fish and Wildlife Service and the National Audubon Society