By: Chris Laskodi M.S., Fisheries Ecologist, Yurok Tribal Fisheries Department
Stoneflies from the family Perlidae aka Golden Stones
If you are a fly fisherman on the Trinity River, you know one of the top flies in the winter is a golden stone nymph. Unsurprisingly, these stoneflies are one of the most common benthic macroinvertebrates found on the Trinity River. They are especially prevalent in the winter and early spring as most of the other insects have already completed their lifecycle and are growing to emerge the following year.
Photo: A stone fly imitation designed to look like the real thing. [Chris Laskodi, Yurok Tribal Fisheries Department]
These stoneflies typically emerge in late spring so they are almost fully grown and are just packing on calories for the next stage of their life cycle. They are avid hunters and consume anything that can fit in their mouths (mostly Chironomids and Baetid larvae). This hunting activity makes them susceptible to entering the drift either voluntary or involuntary potentially providing a tasty morsel for salmonids that are large enough to eat them. TRRP scientists have noticed an uptick of these stoneflies in the last few months during their regular benthic macroinvertebrate surveys providing insight into the stonefly’s behavior.
A stonefly from the family Perlidae captured in a recent benthic macroinvertebrate sample.A Steelhead caught by the author. Note the golden stone imitation in its jaw.
Photos provided by the author.
Chris Laskodi, M.S., Fish Ecologist – Yurok Tribal Fisheries Department
Chris serves as the fish biologist/ecologist for the TRRP in the program’s Science branch. Chris has worked on the Trinity River since 2015, previously serving as a fish biologist for the Yurok Tribe and a fisheries technician for the US Fish & Wildlife Service. Chris holds a B.S. in Wildlife, Fish and Conservation Biology from the University of California, Davis and a M.S. in Aquaculture/Fisheries from the University of Arkansas at Pine Bluff. In his free time, Chris enjoys taking friends and family fishing on one of the many watercraft available to him.
By: Kiana Abel, Public Affairs Specialist – Trinity River Restoration Program
Family: Lycosidae
Wolf spiders are an incredibly common spider worldwide with 2400 described species that range in many different habitats, vary in size and coloration, have incredible eyesight and hunt by ambushing, chasing, pouncing and or tackling its prey. In fact, wolf spiders are classified to the Lycosidae family of arachnids, so named after the Greek word (from Ancient Greek λύκος (lúkos)) for wolf due characteristic hunting tactics of the two species.
Thin Legged Wolf Spider [Howard Bruner, inaturalist – Lewiston]
Carolina Wolf Spider (Hogna carolinensis). [wikimedia commons]
McCook’s Split wolf spider (Schizocosa mccooki). [Joaquin Hale – Lewiston]
California is home to more than 120 species of wolf spiders, ranging from tiny ground dwellers in the genus Pardosa (thin legged wolf spider) to the quite large Hogna carolinensis (Carolina wolf spider). When discerning between genera of wolf spiders, they can be very difficult to identify in the field without holding each type in your hand [or by using this genius method]. Although the wolf spider’s bite is not dangerous to humans (akin to a bee sting) capturing one on camera or in your hand can be difficult because they are fast – and they are, well. Mostly big. Also hairy. And a spider.
Commonly all wolf spiders share traits such as parental care, eight eyes, active hunting techniques and coloration that hides them within their habitat. Knowing these identifying factors, the wolf spider can be distinguished quite easily from other common California spiders such as the brown recluse look alike, Titiotus californicus, tarantulas or black widow.
Desert Tarantula(c) LJ Moore-McClelland via iNatrualist
Western Black Widow. [Joaquin Hale – Lewiston]
Within the Lycosidae family there are 56 described spiders in the genus Schizocosa. Schizocosa mccooki, commonly known as the McCook’s Split Wolf Spider andcan be found in Trinity County. This spider is identified by its medium sized (about 1.5 inches) hairy body, active hunting style, eight eyes (two very large center eyes, four under and two upper eyes) and a distinctive “heart mark” on its abdomen. Most individuals live one year, with mating typically occurring in late summer or fall.
The rearing and mating process for wolf spiders is unique in the spider world. Common to female wolf spiders, S. mccooki carries her egg sac attached to their spinnerets at the end of their abdomen until their spiderlings hatch. Once hatched, the juveniles remain on their mother’s back until they are ready to disperse into the world.
Wolf Spider Mothers Carry their Eggs – YouTube
Common to male Schizocosa is a complex leg-drumming display used to attract females during mating season. A 2022 study, published in Biology Letters, indicates that males use specific vibratory signals to court their desired female, creating unique and more complex patterns for larger females – the study hypothesizes this may be due to choosing a female that has a large carrying capacity for juvenile spiders once hatched (Choi etal, 2022). The study also found that females picked males with complex coordination of differing signals that may indicate her suiters athleticism (Choi etal, 2022).
Wolf spider, Schizocosa stridulans male courtship – YouTube
Spiders typically have eyes that suit their hunting styles, and unlike web-building spiders, wolf spiders rely on keen eyesight to capture prey. As mentioned earlier, wolf spiders have eight eyes, with a large pair front and center. Their eyesight is enhanced by a interior reflective layer called the tapetum lucidum that helps to shine light back into the spider’s vision effectively enhancing low-light conditions that aide them in nocturnal predation.
Tapetum lucidum is an evolutionary feature found in both predators and prey such as cats, deer, cows, and some spider species. If you are ever interested in hunting wolf spiders, simply head out with a headlamp on a moonless night, shine your light into the grass and look for two reflective eyes shining back at you from the darks of your backyard.
Araneomorph spider of which wolf spiders are categorized. Anatomy from Spidentify
Wolf spiders possess forward-pointing chelicerae, an appendage that almost resembles a well groomed mustache yet operates to aid immobilizing prey while fangs deliver venom at it’s tip. In wolf spiders, the chelicerae are relatively large and well-muscled, giving them the strength to subdue struggling insects during active hunts. Viewed closely, the chelicerae appear dark and glossy, sometimes with fine hairs, and the fangs curve slightly inward at the tips. This arrangement is both efficient for piercing prey and distinguish them from other spider groups such as tarantulas, whose fangs move vertically rather than side-to-side.
In S. mccooki, the chelicerae are proportionally large relative to the spider’s body size and are typically dark brown to black with a polished sheen that contrasts against the lighter patterned cephalothorax. Strong internal muscles allow the fangs to strike with enough force to quickly immobilize prey such as beetles or crickets. Fine sensory hairs line the cheliceral margins, helping the spider detect movement and handle struggling prey. In males, the chelicerae can also serve a communicative role, sometimes being lifted or vibrated in coordination with leg-drumming during courtship.
A Riparian Predator & Prey
Riparian corridors are home to a wide range of species that link terrestrial and aquatic food webs. Among these, the wolf spider is a key ground-dwelling predator that helps regulate insect populations and provides prey for higher trophic levels.
Wolf spiders are widespread in open habitats such as grasslands, chaparral, and riparian habitats where cobble bars, woody debris, and leaf litter provide hunting grounds and cover. These microhabitats are important refuges not only for wolf spiders but for the many insects they consume. As wolf spiders actively stalk prey such as earwigs, beetles, ants, and crickets, consuming them helps moderate insect communities which indirectly supports plant health thus contributing to ecosystem stability. S. mccooki and other wolf spiders also contribute to cross-boundary energy flow by serving themselves as prey for birds, amphibians, reptiles, and mammals.
Mccooks Split Wolf Spider carrying its eggsac. [Martin Galli, inatrualist]
Recognizing the ecological functions of wolf spiders highlights why observation is often a better response than eradication. These spiders are integral components of riparian and terrestrial ecosystems, regulating insect populations and serving as prey for higher trophic levels. Their hunting strategies, reproductive behaviors, and physiological adaptations illustrate the complexity of predator–prey interactions that sustain biodiversity. By taking time to identify and observe a spider before removing or killing it, we not only learn more about local species but also foster an understanding of the interconnected roles that maintain ecosystem stability. In this way, simple curiosity can translate into conservation-minded awareness.
As Public Affairs Specialist for the Trinity River Restoration Program, Kiana manages external communications, media relations, and stakeholder outreach. She acts as a liaison between program initiatives and the public, transforming technical findings into compelling narratives that promote understanding of restoration initiatives on the Trinity River. Kiana holds a Batchelor’s in Art History, has spent most of her career in marketing and is focused at the TRRP on bridging the gap between public awareness and resource restoration and management.
By: Michael Dixon, Executive Director – Trinity River Restoration Program
Wait, bats? Of the river? Yes! A river is more than its bed and banks, it is also intricately tied to the valleys, canyons, and forests through which it flows. Many North American bats are tightly associated with proximity to both forest cover and water (e.g. Dixon 2012), and the bats of the Trinity River watershed follow suit. In fact, some of our bats do almost all of their foraging over and near water, which in a dry, mountainous landscape like ours, means over the Trinity River and its tributaries.
Bats fly into a Texas sunset. [US Fish and Wildlife Service]
Bats are the second largest order of mammals in the world, with >1,400 species on every continent except Antarctica, though a majority of those species are in the hyper-diverse tropics. The Klamath Mountains, through which the Trinity River flows, are home to at least 18 species (Reiss, Kauffman, and Feldman 2022). Some of these are year-round residents and are known to hibernate locally, whereas others migrate to warmer climates during the winter. All of our local bat species echolocate, meaning they essentially “yell” in very high frequency sound and then listen for the echoes (the same concept as sonar), which helps them navigate and feed in a dark world.
While the incredible worldwide diversity of bats includes many unique feeding styles such as nectar-feeding flower pollinators, fruit eaters, and (a bat fan favorite) bats that fish for food like the super cool fish-eating myotis, all of the bats in the Trinity watershed eat invertebrates like insects and spiders. That said, there’s a remarkable range of ways that they do that. Let’s take a look at a few of the species that call the Trinity River watershed home.
Myotis species
A little brown bat. [USFWS/Ann Froschauer]
Of the bats discussed here, the five or more small, brown, round-eared species of Myotis in our area are perhaps the closest to what people think of when they think of a “bat”. Their appearance exemplifies the German word for bat, Fledermaus or “flutter mouse”, though bats are much more closely related to deer, whales, and carnivores than to rodents.
Yuma myotis (Myotis yumanensis) are among the most frequently encountered species in the region and are “aerial insectivores”, meaning they forage on flying insects. They can be found flying along forest edges but most commonly over slow-moving water, typically only a couple feet above the river. This is because while they will also take things like moths and beetles, they are strongly predisposed to hunting emerging aquatic insects like caddisflies and midges. They make low, repeated passes over water smooth enough for their echolocation to detect the disturbance of insects on the waters’ surface. In areas where few large trees are found, they will form maternity roosts in buildings; these are where large groups of females gather together to raise their pups until they are old enough to disperse. However, in areas of the West including parts of the Trinity River where there are healthy riparian areas with large, old trees, they will roost in things like hollowed-out old cottonwood trees. This is one of the reasons that the Trinity River Restoration Program attempts to avoid impacts to mature riparian forests when building our restoration projects.
Another Myotis worthy of note is the little brown bat (Myotis lucifugus). While they are less abundant than Yuma myotis in the Trinity River region (Pierson and Rainey 2007), they are strongly predisposed to roosting in buildings and thus relatively commonly encountered. They are noteworthy in that, while fairly generalist in their feeding habits, they eat disproportionately large numbers of mosquitoes, making them allies of their human neighbors (Wray et al 2018). They have quite a large range, extending from the subarctic to the southern US, and through the late 2000s were among the most common bats on in North America. However, they are now classified as endangered by the International Union for Conservation of Nature because of the catastrophic impacts of an introduced disease called white-nose syndrome; it is estimated that the eastern and midwestern populations of the species have declined by 90% since 2010.
Little brown bat (Myotis lucifugus) in a historic building. [Mike Dixon, Bureau of Reclamation]
Pallid bat
A pallid bat (Antrozous pallidus). Photo originally posted on ANAMALIA by Michael Durham/Minden Pictures, BCI
In contrast to the myotis bats described, pallid bats (Antrozous pallidus) are quite large, with a wingspan of up to 16 inches. Beyond their large size, they also have enormous ears that can be a third of their body length. This is because rather than catching insects on the wing, they are gleaners, meaning they hunt prey on structures or, in their case, the ground. They are still capable of echolocation, but their over-large ears also allow them to listen for the sounds of their prey and target them that way. They are particularly fond of scorpions, of all things. Their inconsistent use of echolocation and ground-hunting behavior also means they tend to hunt in more arid or open areas, but they still stay relatively close to water. They frequently roost in trees in northern California (Baker et al. 2008) but can also be loyal users of strategically located buildings as night roosts. Night roosts are places that bats hang out for a variety of reasons including rest, digestion, picking apart large prey items, and various social interactions including information sharing (Ormsby et al. 2007). For several years, I have observed congregations of 5-20 pallid bats in the same corner under my eaves almost every night when overnight lows temperatures exceed 45oF. I appreciate them keeping the front of my house scorpion-free!
Pallid bats (Antrozous pallidus) have frequently used this night roost on a cabin next to the East Branch of East Weaver Creek. [Mike Dixon, Bureau of Reclamation]
Hoary bat
Hoary bats (Lasiurus cinereus) are striking in appearance. Rather than the shades of brown with which bats are often portrayed, the hoary bat has dark fir with brightly frosted tips and a yellowish face. Also unlike many bats of the temperature regions, it doesn’t hibernate – rather, it spends its summers from the northern U.S. (including northern California) well into Canada, and then in the fall migrates sometimes over 2,000 km south to a winter range that extends from the Southwest into Central America (Cryan et al 2004).
A hoary bat (Lasiurus cinereus) roosting on the branch of a tree. [Paul Cryan USGS]
Rather than flying low over the water or ground or on the edges of forest, the hoary bat is a high-flying moth specialist that makes long passes over open water or the top of the forest canopy, sometimes flying almost 25 miles in a night of hunting. The coevolution of bats and moths has been a subject of long study, as there is evidence that echolocation by moth-hunting bats drove the evolution of ears and evasive behaviors in moths, which in turn changed how moth-specialist bats echolocate (Ter Hofstede and Ratcliffe 2016).
Hoary bats are more solitary than most of our bats and tend to roost individually by hanging from tree branches like dead leaves, but they can form large aggregations around landmarks during their long southward migrations. This means that after they leave our Klamath Mountains, they are often recorded in what would seem to be pretty unusual places for a bat – they have been observed swarming ships at sea and commonly recorded over the Farallon Islands 30 miles off the coast of San Francisco. These long, sometimes over-water migrations also presumably led to one of the more unlikely events in the history of bats – the colonization of the Hawaiian Islands over 1.3 million years ago by hoary bats from what is now the west coast of the U.S. In this single founder event, wayward bats established the most isolated bat population in the world, which has since diverged significantly into its own species, the critically endangered Hawaiian hoary bat (Lasiurus semotus).
Bats and people
I have already mentioned how a couple of our native bats benefit people by controlling pests, and that topic has been the subject of many publications. Suffice it to say, bats are very important to the ecology of the Trinity River watershed and provide services to its people here and throughout the world, but they can also be inconvenient and, occasionally, dangerous to people. Here are a few suggestions for living with bats.
First and foremost – while bats don’t “carry” rabies (it is also deadly to them), the abnormal behavior of rabid bats is what often brings them into contact with people. NEVER pick up a bat that you encounter. It is unlikely that it has rabies, but the consequences of contracting rabies are so serious that it is not worth the risk. If you encounter a bat in your house, shoo it out but do not handle if it all avoidable – you’d be surprised how thick of a glove a bat can bite through!
If you have the space for it, embrace an untidy yard. Long grass provides a home for large insects like crickets that are preyed upon by our gleaning bats. Leaving fall leaves until the following spring allows many types of caterpillars and beetle grubs to use them as winter cover, providing food for our aerial insectivores the following summer. Trees with loose bark cavities or large are used by many species for roosting and can be left as habitat where they do not cause a hazard.
Many species like to use buildings for day or night roosts or for hibernation. Sometimes this isn’t a huge deal – I already mentioned that I appreciate the night roost above a seldom-used door at my house, and even use their guano as a garden amendment. However, in confined spaces like the walls and attics of buildings, the guano can become smelly and damage walls, and bats roosting in those places sometimes find their way into parts of those buildings with people (not a good thing, as already discussed). Many pest control companies have experience with excluding bats in a humane way (essentially letting them fly out but not back in). If you need bats evicted from your home, try to wait until late summer when the pups have fledged, so as not to separate foraging mothers from their flightless pups.
If you’d like to encourage bats to use your property, you can build or buy prefabricated bat houses. The trick in a climate like that of the Trinity watershed with sometimes intensely hot days and cool nights is to find the right sun exposure. Nursing mothers and pups want a spot that will gather and retain heat into the evening but will not get so hot during the day as to be uninhabitable. There’s an element of trial and error (and luck) to getting bats to move in, but it’s a great way to provide wildlife habitat and help keep your bugs down. For more resources on gardening and bat houses, this is a great place to start: Bat Gardens & Houses – Bat Conservation International.
References
Baker, Michael D., Michael J. Lacki, Greg A. Falxa, P. Lee Droppelman, Ryan A. Slack, and Scott A. Slankard “Habitat Use of Pallid Bats in Coniferous Forests of Northern California,” Northwest Science 82(4), 269-275, (1 September 2008).
Dixon, Michael D. “Relationship between land cover and insectivorous bat activity in an urban landscape.” Urban Ecosystems 15 (2012): 683-695.
Ormsbee, Patricia C., James D. Kiser, and Stuart I. Perlmeter. 2007. Importance of night roosts to the ecology of bats in Michael J. Lacki, John P. Hayes, and Allen Kurta, eds. Bats in Forests – Conservation and Management. The John Hopkins University Press: pp 129-151.
Pierson, Elizabeth D. and William E. Rainey. 2007. Bat distribution in the forested region of Northwestern California. Report for California Department of Fish & Game, Contract #FG-5123-WM.
Reiss, Karen, Michael Kauffman, and Chris Feldman. Mammals in Michael Kauffman and Justin Garwood, eds. (2022). The Klamath Mountains – A Natural History. Backcountry Press. Pp. 428-430.
Ter Hofstede, Hannah M., and John M. Ratcliffe. “Evolutionary escalation: the bat–moth arms race.” Journal of Experimental Biology 219.11 (2016): 1589-1602.
Mike Dixon is the Executive Director of the Trinity River Restoration Program and a northern California native. He fell in love with the Trinity River and Klamath Mountains while assigned to his first duty station at Coast Guard Air Station Humboldt Bay. He received a Ph.D. in Conservation Biology from the University of Minnesota, Twin Cities, where his dissertation focused on the landscape ecology and population genetics of bats. He lives on a small, perennial tributary of the Trinity River near Weaverville.
Photo: The [much younger] author with a little brown bat in Voyageurs National Park
The northwestern pond turtle (Actinemys marmorata) has lived in the waters of the Trinity River for thousands of years. This species has undergone several taxonomic revisions since first being first described in 1841 (1, 2, 3). It was originally considered a single species with the southwestern pond turtle (Actinemys pallida) and called ‘Emys marmorata’. Then both species were renamed ‘Clemmys marmorata’. The northwestern and southwestern groups were more recently split into two species based on genetic and physical differences between them. So, you may read our local turtles described with different common and scientific names depending on when the document was published (3). But no matter when it was published, there is only one native freshwater turtle known to the Klamath Mountains and the current name is “northwestern pond turtle” (Actinemys marmorata).
Photo: A female northwestern pond turtle. [Don Ashton]
Actinemysmarmorata
actin = ray or beam // emys = turtle // marmorata = marbled
As its common name suggests, the northwestern pond turtle is known to inhabit ponds and lakes, but within the Klamath Mountain ecosystem they are commonly associated with riverine habitats. Northwestern pond turtles are poikilothermic, meaning that they regulate their temperature by basking in the sun when they are cold, and seek cool water or shade when they are too warm. They distribute in sunny, slow water reaches with boulder lined pools that, importantly, have connectivity to broad floodplain habitat (5, p. 353).
A male Northwestern Pond Turtle in underwater refugia on the Southfork Trinity River. [Don Ashton]
The northwestern pond turtle has an acute sense of sight and low-frequency hearing, and while they are often seen basking in the sun above water, they will quickly retreat when they feel threatened (5). Reader, a river enthusiast we surmise, we are sure you’ve witnessed the sound of a plopping western pond turtle off a river log – but did you see them?
Male turtles are known to migrate from river to upland areas to overwinter in riparian shrubs or leaf litter. This trait is not ubiquitous among all turtles as some choose to stay close to their summer habitat by overwintering in banks near the river or pond. Local herpetologist Don Ashton of McBain Associates/Riverbend Sciences has spent decades studying turtles in the Trinity River and said, “Turtles are very smart animals, they tend to migrate close to the high water line (think 100 year floodplain) but over time we have found that in comparison with North Fork Trinity River populations, turtles on the mainstem are found more frequently hibernating and nesting in lower elevation areas, likely due to adaptation of minimized flooding by Trinity and Lewiston Dams.”
In addition to migration for hibernation and summering, female turtles migrate twice for nesting. When they are ready to lay their eggs, they fill their bladders and set off on a slow but steady journey to upland areas to dig their nests. Once in a satisfactory location, the female turtle wets the ground with her urine to help soften it for digging. Once her eggs are laid, she will journey back to her summer habitat.
A Northwestern pond turtle nest, predated. Egg fragments and plug are identified. [Don Ashton]
Migration to upland areas for nesting or hibernation can often lead to chance encounters with humans or their vehicles. If you happen to cross paths with a turtle, Ashton advises to leave them to their journey, “they are not lost” Ashton declares. However, if their location poses a risk of vehicular homicide, and you feel compelled to move them, point them in the direction of their path. That is unless the turtle happens to urinate while being handled, then, Ashton suggests, they should be pointed back toward a water source.
These ancient creatures are small to medium in size, growing up to 8 inches long. Interestingly, Trinity River turtles have been documented as even smaller than their regional counterparts. Some herpetologists surmise this could be due to temperature suppression caused by elevated dam releases causing cold water releases in the latter spring and summer months (6). Watch Don Ashton’s 2024 Trinity River Restoration Program Science Symposium presentation on the subject below.
Don Ashton, Senior Aquatic Herpetologist/Ecologist for McBain Associates/Applied River Sciences presents, “Frogs and Turtles informing flow management and river restoration.” at the 2024 Trinity River Restoration Program Science Symposium.
Their dark brown or olive-colored shells often feature fine, lighter markings that give them a marbled look as reflected in their species name, marmorata. Their low profile and coloring help them blend in with riverbanks, keeping them safe from predators like raccoons, skunks, and birds of prey. The male northwestern pond turtle can be identified with a pointier snout and lighter pale cream coloring under its neck. If you encounter a turtle with hints of red near the ear it is likely a non-invasive red-eared slider, make note of where you are and if possible, provide photo documentation to the Trinity River Restoration Program or the California Department of Fish and Wildlife. Documentation of these instances can help in protecting our native turtle populations.
A female northwestern pond turtle on the Southfork Trinity River. [Garth Hodgson, Don Ashton]Adult male northwestern pond turtle. [Don Ashton]A red-eared slider. [wikimedia commons]
Unlike many reptiles, northwestern pond turtles grow slowly. They start out about the size of a quarter. Females don’t start laying eggs until they’re between 8-10 years old (3, 7, 8). They lay between 3 and 13 eggs, which incubate through the summer. In some parts of Northern California, hatchlings stay in the nest through winter, emerging the following spring. In the photo you can see a comparison of a female turtle at 55 years old with a newly hatched turtle. Ashton, in the background mentioned that the elder at age 55 was carrying 9 eggs at the time of that photo (2018) which suggests their lifespan may be quite long. Ashton mentioned, “it is certainly possible that there are turtles living in the mainstem that have lived there since before the dam was placed.”
Photo: A female, marked and recaptured and aged at 55 years old in comparison with a hatchling. Held by Bruce Bury and Don Ashton smiles from the back in 2018. [Jamie Bettaso]
The northwestern pond turtle has been studied locally for over 50 years due to the diligence of herpetologist Bruce Bury, now retired from USGS, who monitored northwestern pond turtles starting in 1968 while earning his Ph.D. at UC Berkeley. He marked turtles with an identifying notch in a tributary of the South Fork Trinity River, allowing for scientists to track longevity on the only native species known in the Klamath Range (5, p. 354). Although Bury has documented turtles over 50 years old, northwestern pond turtle longevity is still being studied today.
The northwestern pond turtle is commonly seen in the Trinity River, but its population has been declining throughout its west coast range. This decline is so severe that in 2023 the U.S. Fish and Wildlife Service proposed to list the northwestern pond turtle as a “Threatened” species (8, 11). Habitat loss, hydrologic alterations and invasive species are a few human caused threats to northwestern pond turtles. The state of California also recognizes the northwestern pond turtle as a species of “special concern”. As such, handling these turtles requires permitting and are considered illegal to keep as pets.
The Trinity River Restoration Program has been involved in research to identify and address some of these threats. A graduate student from Cal Poly Humboldt, Leah Sloan, determined that non-native bullfrogs (Lithobates catesbeianus) eat young northwestern pond turtle hatchlings to the detriment of their populations along the Trinity River (10). Bullfrogs prefer off-channel ponds, which are perfect areas for northwestern pond turtles to grow. Bullfrogs require perennial ponds to reproduce because their tadpoles take longer than one year to grow (and the mainstem Trinity River is too cold and swift to support bullfrogs year-round), so ponds that normally dry out won’t support bullfrogs permanently. Seasonal drying isn’t much of a concern to turtles because they can simply walk to the river when their home dries up. This is one recommendation for the Program to consider when rehabilitating a site.
A trail camera captures a female northwestern pond turtle basking on a log. [Don Ashton]
Today, turtle researchers and wildlife managers are still learning more about turtle behaviors and how to change management to better serve the northwestern pond turtle in the Trinity River region. From size and aging to nesting sites and travel patterns, each discovery helps build a clearer picture of what these turtles need to thrive.
By: Chris Laskodi M.S., Fisheries Ecologist, Yurok Tribal Fisheries Department
The ‘bug of the month’ for March is the…March Brown. March Browns are mayflies that get their namesake for being, well, brown and for hatching in March. As with most common names for aquatic insects, the name March Brown can apply to several different species of mayfly. On the West Coast, the name March Brown applies to Rhithrogena morrisoni; while on the East Coast, it applies to Stenonema vicarium. This common name confusion is why insect taxonomists use the scientific names (even though those change often too!) to describe insects.
March Browns, like other members of the family Heptageniidae, are known as clinger mayflies in the nymph life stage. Their body shape is extremely flat and their gills often form a suction cup like structure on their underside. They are adept at living in the fastest riffles and can persist high flows without being dislodged like other species. Their persistence to stay where they are means they are not as available to salmonids as other species. Even though they are less available, they are often seen in the drift as they are extremely abundant. We do occasionally find the nymphs in the stomachs of juvenile salmonids; but it is much more common to see the adult life stage being eaten.
Adult March Browns are one of the most prolific hatches of insects in the winter months. Although they cannot meet the numbers of midges or Baetid mayflies, their larger size is a good source of calories for hungry salmonids. They typically hatch February through April although they are most abundant in, you guessed it, March. You will often see a hatch of March Browns bringing juvenile salmonids as well as larger trout to the surface. A March Brown imitation fished as a dry fly is a good way to catch an adult Steelhead in the spring.
Check out this March Brown fly tying tutorial from the Oregon Fly Fishing Shop:
A March Brown adult courtesy The Missoulian Angler Fly Shop. [Les Korcala]
Chris Laskodi, M.S., Fish Ecologist – Yurok Tribal Fisheries Department
Chris serves as the fish biologist/ecologist for the TRRP in the program’s Science branch. Chris has worked on the Trinity River since 2015, previously serving as a fish biologist for the Yurok Tribe and a fisheries technician for the US Fish & Wildlife Service. Chris holds a B.S. in Wildlife, Fish and Conservation Biology from the University of California, Davis and a M.S. in Aquaculture/Fisheries from the University of Arkansas at Pine Bluff. In his free time, Chris enjoys taking friends and family fishing on one of the many watercraft available to him.
You may notice a distinct absence of bugs flying above the river during these winter months. However, if you look closely you’ll find an active colony of tiny midges buzzing on the surface. These midges, despite their small size, are extremely important to the ecology of the Trinity River. Midges belong to the ‘true flies’ (order Diptera) and are related to other flies such as houseflies, craneflies, and mosquitoes.
Midges are often referred, especially by Trinity River Restoration Program scientists, as chironomids. This is because they belong to the family Chironomidae within the order Diptera. Chironomids are extremely diverse and are found worldwide in all types of different aquatic environments. Some are extremely tolerant of low oxygen and pollution; some even have a hemoglobin analog to survive in low oxygen environments. Others are extremely sensitive to poor water quality. Chironomids are often used to determine the health of streams because of the diversity of different water qualities they can tolerate.
Chironomids are especially important to the ecology of the Trinity River because they are a major food source for juvenile salmonids and other native species. Chironomids are known as a pioneer species which means they are the first to colonize new habitats. During the winter, when seasonal floods are wetting new landscapes, Chironomids take advantage. Their short life cycle (usually between 6 and 12 weeks) enables them to exploit habitat extremely quickly. This often results in a Chironomid ‘bloom’ (see picture). These seasonal ‘blooms’ often coincide with the emergence of salmonids from the gravel.
The chironomids small size and high abundance make it an easy first meal for tiny salmonid mouths. Chironomids along with Baetid mayflies profiled last month, are some of the most important food sources for juvenile salmonids during their outmigration to the ocean.
Figure Captions
A larval Chironomid [photo courtesy of Bugguide.net]
Newly inundated floodplain habitat with a Chironomid ‘bloom’. Each one of the tube-like structures are cases that Chironomids construct out of fine sediments. [Chris Laskodi, Yurok Tribe]
Chris Laskodi, M.S., Fish Ecologist – Yurok Tribal Fisheries Department
Chris serves as the fish biologist/ecologist for the TRRP in the program’s Science branch. Chris has worked on the Trinity River since 2015, previously serving as a fish biologist for the Yurok Tribe and a fisheries technician for the US Fish & Wildlife Service. Chris holds a B.S. in Wildlife, Fish and Conservation Biology from the University of California, Davis and a M.S. in Aquaculture/Fisheries from the University of Arkansas at Pine Bluff. In his free time, Chris enjoys taking friends and family fishing on one of the many watercraft available to him.
Mayflies from the family Baetidae are this month’s ‘bug of the month’. Commonly known as blue winged olives by fly fishermen, Baetid mayflies are small (<10mm) and can be extremely prolific. In addition, they grow rapidly and can have multiple generations within a year (known as multivoltine). This means that you can see adult Baetid mayflies during most of the year although they are especially apparent during the winter in early spring when few other bugs are hatching.
Photo Credit: TroutNut.com
Baetid mayflies are exceptionally adept at colonizing new habitat. They are extremely good swimmers (for a bug) and are known for undertaking what is known as behavioral drift. Behavioral drift is a strategy where macroinvertebrates enter the flow of the river voluntarily to seek out new habitat. Short life cycles, excellent swimming ability, and the propensity to undertake behavioral drift allow them to settle new habitat like when high flows inundate floodplains.
They are often the first to colonize a new area due to their swimming skills and their preference for shallow, slow water. These newly formed areas grow algae very well which is the primary food source for Baetid mayflies. They can often exploit newly formed habitat within a few weeks and live their entire life cycle within 12 weeks before other bugs get a chance to settle in an area. Seasonal inundation of floodplains are extremely important to Baetid mayflies success. Juvenile salmon have evolved to depend on the seasonal inundation of floodplains because of the presence of Baetid mayflies, which they eat for food.
Chris Laskodi, M.S., Fish Ecologist – Yurok Tribal Fisheries Department
Chris serves as the fish biologist/ecologist for the Trinity River Restoration Program in the program’s Science branch. Chris has worked on the Trinity River since 2015, previously serving as a fish biologist for the Yurok Tribe and a fisheries technician for the US Fish & Wildlife Service. Chris holds a B.S. in Wildlife, Fish and Conservation Biology from the University of California, Davis and a M.S. in Aquaculture/Fisheries from the University of Arkansas at Pine Bluff. In his free time, Chris enjoys taking friends and family fishing on one of the many watercraft available to him.
Dicosmoecus (dee-co-smee-cus) caddisflies are better known by the common name ‘October caddisflies’. These caddisflies are notable for there extremely large size (1-2 inches), their concentrated emergence window (October), and their abundance especially in streams containing anadromous fish. These characteristics make it one of the most important hatches to not only fly-fishermen, but to wildlife such as birds as well.
Dicosmoecus like other caddisflies have three life stages: larvae, pupae, and adult. Larvae build cases out of small rocks which serves as protection and their housing. They drag these cases around while foraging for food, mostly algae and detritus. Dicosmoecus are especially notable by the large distances they can cover (up to 25 meters per day) to forage (Resh et al. 2011).
They continually grow and have to build new cases as the old ones become too small. After molting five times (called instars), they attach their cases to the underside of rocks and began to pupate. After about a month of pupating, they cut a hole in their case and swim to the surface before shedding their exoskeleton one more time and becoming adults.
Caddisflies, unlike mayflies, will live for several weeks while they seek out a mate. You will often see them active at dusk and just after sunset. Keep a look out for the large moth-like bugs during sunset for the next few weeks.
References
Resh, V.H., M. Hannaford, J. Jackson, G.A. Lamberti, and P.K. Mendez. 2011. The biology of the limnephilid caddisfly Dicosmoecus gilvipes (Hagen) in Northern California and Oregon (USA) streams. Zoosymposia 5:413-419.
Images courtesy of Red’s Fly Shop and Troutnut.com
Chris Laskodi, M.S., Fish Ecologist – Yurok Tribal Fisheries Department
Chris serves as the fish biologist/ecologist for the TRRP in the program’s Science branch. Chris has worked on the Trinity River since 2015, previously serving as a fish biologist for the Yurok Tribe and a fisheries technician for the US Fish & Wildlife Service. Chris holds a B.S. in Wildlife, Fish and Conservation Biology from the University of California, Davis and a M.S. in Aquaculture/Fisheries from the University of Arkansas at Pine Bluff. In his free time, Chris enjoys taking friends and family fishing on one of the many watercraft available to him.
You may have noticed a rather large insect fluttering down the river during the months of September and October. These insects are mayflies from the family Isonychiidae (eye-son-nic-ee-uh-day) (known in the fly-fishing community as Mahogany Duns or Slate Drakes). Isonychiidae mayflies are one of the largest, if not the largest mayfly found in the Trinity River.
Mayflies are unique in that they have two adult stages in their lifecycle while all other insects have one. The sub-imago stage (dun if you’re a fly fisherman) is a non-reproductive winged stage. The sub-imago stage typically only lasts a few hours as the mayfly molts one more time to become a fully reproductive adult. The final stage is known as the imago (spinner in fly fishing terms). The imago’s sole job is to reproduce. In fact, mayflies do not have functional mouthparts as adults which means they can only live for a short time. Their scientific name (Ephemeroptera) attributes this fact. Ephemera comes from Latin and Greek meaning “daily” or “lasting a day” while ptera comes from Latin meaning “winged”. Keep a lookout for these “briefly winged” insects over the next month.
Isonychiidaemayflies usually live an entire year in the river as nymphs before swimming to the edges of the river, crawling out of the river on a rock, and emerging into their sub-adult stage. As adults, they typically only live for a day or two as their only job is to mate, lay eggs, and then die. Isonychiidae mayflies are noted for their large size compared to other mayflies and for their unique swimming ability. They are very adept swimmers and use their swimming prowess to capture their prey. They also have fine hairs on their forelegs which trap algae and other detritus which they then consume. The nymphs are a very strange looking (compared to other mayflies) and are readily identifiable by their elongated shape and ‘racing-stripe’ down their backs. Looking closely, the hairs on their forelegs become readily apparent and they are very easy to identify for any aquatic entomologist.
Isonychiidae mayflies are unique to the Trinity River with other populations scattered across northern California. The nearest population is found in the Pit River, but are rare there. The population in the Trinity River seems to be thriving and right now is the best time to see both the nymphs and adults. Look for the nymphs along the streambanks where they will look like small fish darting between the rocks. You will notice their shed exuviae (exoskeletons) attached to rocks. Adults can be found in the early afternoon fluttering in the air above the river. They seem to be more common in the area between Junction City and Cedar Flat.
Chris Laskodi, M.S., Fish Ecologist – Yurok Tribal Fisheries Department
Chris serves as the fish biologist/ecologist for the TRRP in the program’s Science branch. Chris has worked on the Trinity River since 2015, previously serving as a fish biologist for the Yurok Tribe and a fisheries technician for the US Fish & Wildlife Service. Chris holds a B.S. in Wildlife, Fish and Conservation Biology from the University of California, Davis and a M.S. in Aquaculture/Fisheries from the University of Arkansas at Pine Bluff. In his free time, Chris enjoys taking friends and family fishing on one of the many watercraft available to him.
If you’ve been lucky enough to spend time on the Trinity River lately, you will notice a plethora of brassy-green colored dragon flies hovering above the river fervently darting to and fro. The species you are most likely viewing is the common green darner Anax junius. Common is in its name, and that is certainly the case, for this species of dragonfly is the most common and abundant throughout North America. The remainder of its common name, Darner, is given due to its resemblance to a darning needle a blunt-tipped larger needle used for repairing holes or tears in coarse knitted cloth.
Dragonflies need water to reproduce. In the summer or early fall, common green darners seek riparian areas with slow water so they can mate and lay eggs in water-bound plant material. The female and male mate in an expertly posed “mating wheel” position – where the two are connected at their reproductive centers, the head of the female with the base of the male’s abdomen. The female’s abdomen is wrapped under the male so they can fly through the air, sometimes for several minutes. The female then unwraps her abdomen and lays eggs into the water while still attached to the male.
A female common green darner (left) in tandem position with male (right) deposits eggs. Ken Slade, Source: nps.org
Eggs hatch into macroinvertebrates (tiny aquatic larvae) after about a week incubation period and then go through upwards of a dozen nymphic molts eating aquatic insects, small fish and even tadpoles as they grow. At the end of the transformational nymph stage, Anax junius, emerges from the water to undergo metamorphosis into a dragonfly from a crack in the exoskeleton.
Common green darner aquatic nymph. Douglas Mills. Originally posted by the National Park Service.
Once the wings are developed enough to fly the darner becomes a ravenous forager eating mosquitos, midges, flies, wasps, moths and other flying insects. This dragonfly species has two different population types, resident and migratory. Residents remain in the general area from which they emerge. For residents in the north, the adults mate and lay eggs in late July to August. The resulting offspring hatch and develop to immature dragonflies and then overwinter when temperatures drop.
Adults that migrate tend to arrive in the northern regions in the spring before any of the residents emerge. Migratory adults mate and lay eggs in June. The migratory dragonfly’s development stage is less than that of the resident variety (3-5 months versus the 11 months of the resident) and they do not overwinter as residents do.
Common green darner’s in September on the Trinity River. James Lee, Trinity River Restoration Program
