The dorsal ground color of adults is variable, ranging from olive green to grayish blue or black. Brown or black spots can be seen scattered on the dorsum of lighter colored individuals. The venter is lighter than the back and white or yellowish flecks may occur on the sides (Martof 1973; Petranka 1998). Hatchlings and juveniles are more brightly colored than adults, having light stripes along the body and yellow or red banding on the head (Martof 1973; Petranka 1998). The bright colors and stripes fade and the dorsal fin on the back is lost as animals age (Petranka 1998).

Two or three subspecies are recognized and can be distinguished based on distribution (see below), size, and coloration. Siren i. intermedia, the eastern lesser siren, is a dark colored form, sometimes having tiny black spots on the dark brown or black dorsum. The venter is also dark, without spots or mottling, and lighter than the dorsum. Maximum length is about 38 cm, and the modal number of costal grooves is 32-33. Siren i. nettingi, the western lesser siren, is olive green to gray with tiny black spots on the dorsum. The venter is also dark with numerous light flecks. Maximum length is 50 cm, with a modal number of 35 costal grooves. Siren i. texana, the Rio Grande siren, is the largest subspecies, reaching 69 cm total length, and having a modal costal groove count of 37. The dorsum is gray to brownish gray with tiny black spots and the venter is light gray. Descriptions from Petranka (1998)

Siren intermedia, the Lesser Siren, ranges from the Coastal Plains of Virginia to Florida, then westward to southern Texas and northeastern Mexico. Populations extend northward in the Mississippi Valley to Illinois, Indiana, and southwestern Michigan. Geographic isolates occur in northern Indiana, southwest Michigan, northeastern North Carolina, and southeastern Virginia.(Petranka 1998) This range is occupied by three subspecies, they are S. i. intermedia, S. i. nettingi, and S. i. texana. All of these subspecies only vary slightly in physical characteristics such as length and color (Conant and Collins, 1998).

Biogeographic Regions: nearctic (Native )

occurs (regularly, as a native taxon) in multiple nations

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) This species occurs in the coastal plain from Virginia to central Florida and eastern Texas in the United States, and adjacent Mexico in northern Tamaulipas and northern Veracruz, and northward in the Mississippi Valley to southern Michigan in the United States.

Lesser sirens are found in a diversity of permanent and semi-permanent aquatic habitats including swamps, marshes, ditches, canals, sloughs, farm ponds, temporary pools in floodplains, and shallow heavily vegetated ponds with deep sediments into which they burrow. See Petranka, (1998) and references therein.

Siren intermedia is an eel-like salamander with a long slender body (18-68 cm long) and a very small dorsal fin that runs from the vent to the tail tip. It has only a pair of front legs; each foot has four toes. The front legs are very reduced and the rear legs are completely absent. The head is rather flattened, and there are bushy external gills located on each side of the head. Siren intermedia varies in coloration from light grayish green to olive or black; there are also small irregular markings (dots) that are visible on lighter colored individuals.

Larvae and juveniles are more brightly marked, with a red band across the nose and along the side of the head.

Other Physical Features: endothermic ; ectothermic ; heterothermic ; bilateral symmetry

Length: 69 cm

Subspecies INTERMEDIA differs from SIREN LACERTINA in having fewer costal grooves (31-35 vs. 36-40) and in lacking any pronounced light markings (Conant and Collins 1991). They differ also in that size at sexual maturity and egg diameter are larger in LACERTINA than in INTERMEDIA (Flores and Brandon 1992).

• Terrestrial
• Freshwater

Siren intermedia will inhabit most any slow and sluggish body of water that is shallow and with plenty of aquatic vegetation, including marshes, ponds, ditches, and canals. In most circumstances they need a permanent or semi-permanent body of water but they are able to move short distances over land if factors are right or stay encased in a cocoon of slime if drought occurs.

Habitat Regions: temperate ; freshwater

Aquatic Biomes: lakes and ponds

Wetlands: marsh ; swamp ; bog

Comments: It inhabits shallow, warm, quiet, sometimes turbid waters with abundant vegetation: swamps, sloughs, ponds, lakes, ditches, and to a lesser degree rivers and streams. It hides among plants and debris by day and burrows into bottom mud if water dries up. The eggs are laid in water in a small pocket or debris-covered cavity in bottom mud.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Eubanks et al. (2002) observed 15 Siren intermedia moving upstream in a rapid flow of water through a 40-m-long concrete culvert between two ponds. The forelimbs appeared to essential in the movement.

In southeastern Missouri, home ranges of adults overlapped considerably and were highly variable in size, ranging from 1 to 232 square meters (Frese et al. 2003).

Siren intermedia feeds primarily on aquatic invertebrates such as crustaceans, insect larvae, worms, and snails. They will also readily consume young amphibian larvae and their own eggs. Siren intermedia often feeds by gulping large quantities of material at a time, which is filtered through the bronchial openings. Vegetable matter sometimes found in their digestive tracts is probably eaten accidentally.

Animal Foods: insects; terrestrial non-insect arthropods; mollusks; terrestrial worms; aquatic crustaceans

Primary Diet: carnivore (Insectivore , Eats non-insect arthropods, Molluscivore , Vermivore)

Comments: Eats various aquatic invertebrates (crayfish, worms, mollusks) and some plant material. Sometimes eats amphibian eggs.

About 1200 were found frozen in an ice-covered pond in Arkansas (Sugg 1988). Density in southeastern Missouri was 1.35 to 2.17 sirens per square meter (Frese et al. 2003).

Comments: Apparently inactive during winter in the north. Active all year in the south except during periods of drought. May remain inactive (burrowed in substrate, in mucous cocoon) for extended periods during drought. Most active in fall and winter and least active in summer in a temporary pond in Louisiana (Raymond 1991).

Average lifespan

Status: captivity: 6.3 years.

The courtship behavior of Siren intermedia has not yet been described. Fertilization has been presumed to be external, since the females lack cloacal sperm storage areas. There is thought to be a lot of aggression during mating due to the amount of scaring from bite marks on both the males and females. Eggs are laid in early spring they are deposited in shallow depressions in the soft bottom of the occupied water body, usually in highly vegetated areas. In these shallow depressions the female will lay from 12 to over 300 eggs; the female may lay multiple clutches through out the season. Freshly laid eggs are dark brown and 2.5-3 mm in diameter. The hatchling larvae are about 1.1 cm in length. (Petranka 1998; Harding 1997)

Average number of offspring: 200.

Average age at sexual or reproductive maturity (male)

Sex: male: 730 days.

Average age at sexual or reproductive maturity (female)

Sex: female: 730 days.

In South Carolina, oviposition occurs during February-April; fertilization evidently is external (Sever et al. 1996, J. Morphol. 227:335-348). Lays clutch averaging about 200 eggs in winter (e.g., in Louisiana, Raymond 1991) or early spring. Female guards eggs. Sexually mature in 2 years. Paedomorphic.

The skin of the lesser siren protects from desiccation by secreting a mucus cocooon.

Siren intermedia is extremely rare and possibly extirpated in Michigan but this species is not threatened over most of its range. It could be harmed by chemicals such as Rotenone, which is used as a fisheries management tool and can be fatal to aquatic amphibians such as Siren intermedia. Another factor that may affect the vitality of this species is habitat destruction and the filling in of wetlands.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Intrinsic Vulnerability: Moderately vulnerable

Environmental Specificity: Moderate to broad.

Global Short Term Trend: Relatively stable to decline of 30%

Comments: Likely relatively stable in extent of occurrence, unknown trend in population size, area of occurrence, and number/condition of occurrences.Field studies are needed to assess the status of this species in Mexico and confirm its existence in northern Veracruz, from where there have been only a few records. It is a common and secure species in many areas in the United States.

Global Long Term Trend: Increase of 10-25% to decline of 50%

Comments: Likely relatively stable in extent of occurrence, unknown trend in population size, area of occurrence, and number/condition of occurrences.

Biting of females by males apparently occurs during the mating season (Godley 1983; Fauth and Resetarits 1999), but bite marks have also been reported on males (Raymond 1991; Fauth and Resetarits 1999). This and the fact that biting also occurs outside of the mating season (on males and females) suggests that there is male-female and male-male aggression; females have not been found to bite other females (Fauth and Resetarits 1999).

When temporary water bodies dry, sirens burrow into soft mud and can aestivate for several months until the ponds fills again (Petranka 1998). Diet of sirens includes a variety of aquatic invertabrates both benthic and pelagic (Petranka 1998). Sirens are locally abundant and densities have been estimatied as 0.9-1.3 sirens/m²(Gehlbach and Kennedy 1978). Sirens are known to vocalize, and they emit barks, yelps, and clicks in intraspecific interactions and also when disturbed (Petranka and references therein 1998).

Comments: It is unthreatened overall, but many local populations have been reduced or extirpated by loss of wetlands (Petranka 1998). The extent to which flood control has reduced opportunities for dispersal among local populations is unknown (Petranka 1998). Disturbance and alteration of the original habitat as a consequence of the industrial activities in the area is also a threat.

Management Requirements: Herbicides used to control aquatic vegetation should be avoided.

On occasion a Siren might take a fisherman's baited hook, but this would be an uncommon and minor annoyance. These animals are properly considered harmless to human interests.

Sirens are occasionally used for fish bait, but this species normally attracts little attention from humans. They occupy a predatory niche in shallow freshwater habitats, and have ecological value in the environment.

Comments: See Sugg (1988) for an account of morphological variation in subspecies NETTINGI. Flores-Villela and Brandon (1992) noted the absence of characters that unequivocally diagnose SIREN INTERMEDIA TEXANA; they concluded that subspecies TEXANA is an invalid taxon and placed it in the synonymy of S. I. NETTINGI. However, subsequent studies indicate that the siren in extreme southern Texas that formerly was included in S. INTERMEDIA may be a distinct species.