Gilt darters are native to North America and can be found from eastern Minnesota to western New York, south to northern Arkansas, Mississippi, Alabama, and Georgia. Currently, its geographic range is declining due to erosion, siltation, man-made water obstructions, and pollution. ("NatureServe", 2010)
Gilt darters inhabit relatively clear, freshwater streams and rivers. Inhabited streams and rivers range from 20 to 100 m wide, with flow rates ranging from 0.5 to 1.2 m/sec, year round. Gilt darters migrate to different depths depending on season. During spring and early summer, they spawn in shallow, swift moving riffles and raceways of the stream. After breeding season, gilt darters reside in the deeper caverns and sediment-free, gravelly beds where they remain for the rest of the year. ("Minnesota Department of Natural Resources", 2011; Hatch, 2004)
Gilt darters are midsized when compared to other fish in the darter family. In general, they are fairly small, measuring about 6.35 cm in length. The dorsal surface of gilt darters is colored dark olive and the sides and belly are typically a striking bronze. This stout and compressed fish has five to eight dark bands, depending upon its age, that run across its back and down its sides. Gilt darters are sexually dimorphic during breeding season. They have a homocercal caudal fin, and the anterior dorsal fin has 10 to 13 spines. The membrane between dorsal spines tends to be dark and the tips of the spines are orange. Similarly the posterior caudal fin has 11 to 13 soft rays; however, this fin is more translucent and colorless. The caudal, anal, pelvic, and pectoral fins all have orange pigments near their bases, but the majority of these fins is colorless. The anal fin has approximately 2 spines and 8 to 11 rays and is colorless. ("Minnesota Department of Natural Resources", 2011; Dickson, 2008; Eddy and Surber, 1947; Phillips, et al., 1982)
Male gilt darters fertilize the eggs released by the female, resulting in hundreds of offspring. The eggs measure at 1.1 to 1.4 mm in diameter, and harden when they come into contact with water. Eggs are yellow to orange in color and hatch in about 8 to 10 days, when water temperatures are approximately 20°C. Larvae measure 4.0 to 4.8 mm long. This stage of their life lasts only lasts about 1 week until they become juvenile gilt darters. (Hatch, 2004)
Gilt darters are polyandrous, as multiple males mate with a single female. When breeding season ensues, the behavior and appearance of males changes dramatically. The upper body turns a dark blue-green while the ventral surface becomes an iridescent yellow or orange. Their sides become blotched with dark pigment, while the bases of each of its fins become dark blue. Males compete for access to mates by establishing a breeding territory around cobbles and small rocks in the shallow riffles of its habitat. They become highly aggressive towards potential rivals. During this time, they frequently use techniques such as chasing, tail-beating, confident body posturing, and rapid color change tactics to defend their territory from potential rivals. Conversely, when a female enters a male's territory, she is promptly pursued. If the female is interested, she displays attractive body posturing and uses tactile stimulation to further entice the male. Gilt darters bury their eggs in the gravel or sandy bottoms of streams that have consistent flow rates. Once the female decides upon a location, the male and female begin to mate. The male swims next to the female in a head-to-head position and they begin vigorously quivering while discharging sperm and eggs. While they are mating, the pair pushes down on the substrate to bury their eggs from potential harm. (Dickson, 2008; Hatch, 2004)
Gilt darters breed once annually during summer, when water temperatures are 17°C or warmer. Mature females lay 132 to 762 eggs, with an average of 247 eggs. Eggs take approximately 8 to 10 days to mature into the larval stage. Time to reproductive maturity varies with sex. Males reach sexual maturity by 11 to 13 months of age, and females reach reproductive maturity by 22 to 23 months of age. (Hatch, 2004)
There is no parental investment in gilt darters besides development, laying, and fertilization of eggs.
Wild gilt darters have an average lifespan of 2 to 3 years. Occasionally, some may live for up to 4 years. It is thought that less than 10% of 1-year old individuals live to the age of 3. There is no information available regarding the average lifespan of captive individuals. (Hatch, 2004)
Compared to other darters, gilt darters are highly mobile. They have a small gas bladder that enables them to have greater mobility and and maneuverability across the entire water column. They have been observed actively swimming around their habitat more frequently than other comparable darters. While other darters use their pelvic fins and pectoral fins to "dart" around the bottoms of streams and rivers, gilt darters swim more often than they dart. (Dickson, 2008; Phillips, et al., 1982)
There is no information available regarding the average home range size of gilt darters. (Phillips, et al., 1982)
One of the most important perception organs for any fish is their lateral line. It is a conspicuous line that runs along the middle of their body, from the opercle to the beginning of their caudal fin. Its functions include water current sensation and vibration detection. Gilt darters use their eyes, internal ears, and lateral line to perceive environmental stimuli. There is no other information regarding communication and perception in this species. (Eddy and Surber, 1947)
Gilt darters are insectivorous, with most prey consisting of aquatic insect larvae. They locate prey mostly by vision, and feed during the early to middle portion of the day. From April through August, food tends to be highly abundant but significantly decreases during September. As a result of the high degree of variability in insect prey, gilt darters are considered opportunistic feeders and feed mostly when larvae begin hatching during spring. Primary prey includes mayflies, caddisflies and other flies. They are also known to consume midges and black fly larvae. One study showed that gilt darters have a preference towards different larvae in different stages in their life. For example, juveniles feed more on caddisflies in the first two months of their lives than when they are adults. In addition, young darters and darters preparing to breed feed more heavily on mayflies than any other food source. ("NatureServe", 2010; Hatch, 2004)
Little is known about the specific predators of gilt darters; however, the fast water currents and riffles of rivers and streams make excellent safe zones from predators. Since darters in general stay at or near the bottom of their habitat, it also keeps them away from predators that like to hunt for prey near the middle and lower depths of the water column. Their swimming techniques (e.g., speed and darting) allow them to outmaneuver a lot of predators as well. Despite this, gilt darters are likely preyed upon by large piscivorous fish. (Hatch, 2004; Shiels, 2011)
As insectivores, gilt darters may help control insect pest species, and despite a lack of information on their potential predators, they are likely prey for a number of different piscivorous fish species as well. Finally, gilt darters play an important role in mussel reproduction, as they are common hosts for numerous species of mussel glochidia, including rabbitsfoot mussels. (Shiels, 2011)
Gilt darters are often used as biological indicators of habitat quality for aquatic ecosystems. ("Minnesota Department of Natural Resources", 2011)
Gilt darters are widely distributed throughout the Midwest and northeastern United States. However, in certain areas throughout their geographic range, they are considered a species of special concern due to their significant population decline over the past 50 years. Damming increases siltation rates and turbidity, which buries breeding grounds. Siltation likely disrupts feeding behavior as well by significantly reducing water clarity and prey habitat quality. This species has not been evaluated by the IUCN and has been given no special status by the United States Fish and Wildlife Service. ("Minnesota Department of Natural Resources", 2011)
Prior nomenclature and authority: Alvordius evides Jordan and Copeland in Jordan 1877a:44; Ericosma evides Jordan 1877b:8-9; Hadropterus evides Forbes 1884:65; Percina evides Bailey and Gosline 1955:14. (Hatch, 2004)
Prior to 1955, gilt darters were referred to in the Minnesota literature as Hadropterus evides. The Cannon River specimen referred to by Carlander (1941) and Eddy and Underhill (1974) is a misidentified Percina maculata (Hubbs 1945). (Hatch, 2004)
Steve Sveine (author), Minnesota State University, Mankato, Robert Sorensen (editor), Minnesota State University, Mankato, John Berini (editor), Special Projects, Catherine Kent (editor), Special Projects.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
uses sound to communicate
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
uses smells or other chemicals to communicate
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
fertilization takes place outside the female's body
union of egg and spermatozoan
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
An animal that eats mainly insects or spiders.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
Referring to a mating system in which a female mates with several males during one breeding season (compare polygynous).
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
movements of a hard surface that are produced by animals as signals to others
uses sight to communicate
2011. "Minnesota Department of Natural Resources" (On-line). Accessed April 28, 2011 at http://www.dnr.state.mn.us/rsg/profile.html?action=elementDetail&selectedElement=AFCQC04090.
2010. "NatureServe" (On-line). Accessed April 28, 2011 at http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Percina+evides+.
Dickson, T. 2008. The Great Minnesota Fish Book. Minneapolis: The University of Minnesota Press.
Eddy, S., T. Surber. 1947. Northern Fishes. Minneapolis: The University of Minnesota Press.
Froese, R. 2010. "FishBase" (On-line). Percina evides. Accessed April 28, 2011 at http://www.fishbase.org/Summary/SpeciesSummary.php?ID=3493&AT=gilt+darter.
Hatch, J. 2004. "Gilt darter" (On-line). Accessed April 28, 2011 at http://hatch.cehd.umn.edu/research/fish/fishes/gilt_darter.html.
Phillips, G., W. Schmid, J. Underhill. 1982. Fishes of the Minnesota region. Minneapolis: The University of Minnesota Press.
Shiels, . 2011. "Pennsylvania Fish and Boat Commission" (On-line). Pennsylvania's Dynamic Darters. Accessed May 01, 2011 at http://www.fish.state.pa.us/education/catalog/darters.html.