Males use songs to attract females, but unlike many songbirds they do not use this song to establish territory. They often sing in flight. Their most common song can be mnemonically described as 'k-chinnnng doot' and sounds like two short chips with a dry hiss in between. Females use warning calls to alert offspring of danger and threatening calls to ward off males from nests. No observations of female songs have been made. Females also use body posture to communicate willingness to mate. When a female encounters a male and is ready to breed, she may crouch with her tail and bill raised, and hold her wings folded and slightly raised. Like most birds, Ammodramus nelsoni perceives its environment through visual, auditory, chemical, and tactile stimuli.
Communication Channels: acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
The main threat to Ammodramus nelsoni is habitat loss due to human destruction; mostly because of conversion of grassland and marshes for agricultural uses. Because specific water depth is important to the species, it is essential to protect large areas of habitat to make certain that the ideal water conditions are present in at least a few areas within a wetland. Currently, the International Union for Conservation of Nature and Natural Resources lists this species as Least Concern and considers the population to be stable and widespread. However, increasing human development and resulting habitat loss should be monitored closely. As a migratory species, Ammodramus nelsoni is protected under the United States Migratory Bird Act.
US Migratory Bird Act: protected
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
There are no known negative effects of Nelson's sharp-tailed sparrows on humans.
Nelson's sharp-tailed sparrows do not have any economic benefits for humans.
As omnivores, these sparrows likely affect local seed distribution as well as insect populations. The adults and young also serve as food for several aerial and land predators. Nest parasitism sometimes occurs in Ammodramus nelsoni nests. The only documented brood parasites for this species are brown-headed cowbirds (Molothrus ater).
Commensal/Parasitic Species:
Ammodramus nelsoni is an omnivore, and procures the bulk of its food from grass stems or on the ground. In warmer months, their diets include insects, spiders, amphipods, and other small invertebrates. During winter months, seeds and grains provide the sparrows' sustenance.
Animal Foods: insects; terrestrial non-insect arthropods
Plant Foods: seeds, grains, and nuts
Primary Diet: omnivore
Ammodramus nelsoni, or Nelson's sharp-tailed sparrows, have three separate distributions within the Nearctic region. One population resides around Hudson Bay in Canada. The other two inhabit both Canada and the United States: one population ranges along the north Atlantic Coast from Quebec down to Maine and the other is in the center of North America, ranging over Minnesota and northwest North Dakota to Alberta and southern Mackenzie River basin in Canada. All populations migrate to winter along the southern Atlantic and Gulf of Mexico coastlines. Small numbers are also found wintering in a similar habitat along California’s coast.
Biogeographic Regions: nearctic (Native )
Ammodramus nelsoni prefer grassy areas that are within wetlands. Common sites are freshwater marshes at the edge of woodland lakes, brackish marshes, sedge bogs, and regions between creeks and wet meadows. Willow trees are the preferred nesting site for this species, so they are often found in habitats where these woody plants are abundant. Within these habitats, a water depth between 1 to 10 inches is ideal. Water depths are most important during the breeding season. If a site is too wet or too dry, Ammodramus nelsoni will most likely not live in that location. Ammodramus nelsoni winters in saltwater and brackish marshes.
Habitat Regions: temperate ; terrestrial
Aquatic Biomes: coastal ; brackish water
Wetlands: marsh ; bog
Other Habitat Features: estuarine
Using banding data, the maximum observed lifespan is 10 years for males and 6 years for females.
Estimates of minimum annual survival of adults in 2 cohorts (in New York) were 60.3% and 54.7% in males, and 63.3% and 53.0% in females. Offspring survival into first fall is estimated as 31.1%. In a 2-year study in Rhode Island, tidal flooding caused 60% of egg and nestling mortality. Flooding was also found to be the main cause of egg and nestling mortality in Canada and New York. There is little known regarding causes of adult mortality.
Range lifespan
Status: wild: 6 to 10 years.
Ammodramus nelsoni is noted for its sunny, golden-orange color extending from the eyebrows to the breast, where it is mottled with darker stripes. The sparrow’s gray-striped crown is bordered with dark brown, and the ear coverts are gray. The olive-brown upper body and neck are notably streaked with white or gray. White extends down the abdomen to its brown, tapered tail. They are small birds; weighing in at 19 to 21 g. They measure 11 to 13 cm in length and feature a 20 cm wingspan. The more common Le Conte’s sparrows (Ammodramus leconteii) have a similar appearance to Ammodramus nelsoni. Differences include Le Conte’s sparrows' striped gray napes and more subtle sandy-streaked backs.
Three subspecies exist, based on location. Two subspecies are found in the United States and one inhabits British Columbia. Nelson's sharp-tailed sparrows are sexually dimorphic. Both sexes look similar, but males are slightly larger than females. Juveniles have brown ear coverts and less distinct facial markings.
Range mass: 19 to 21 g.
Average length: 127 mm.
Average wingspan: 20 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes alike; male larger
Females silently abandon their nests and hide when a potential ground predator comes near. She will give warning calls when dependent young are present and fly within 10 to 15 m of nest. Females return to the nest after the potential predator leaves the immediate nest area. An alarm call may be given when an aerial predator approaches, but typically the sparrows silently find cover. No nest-distraction displays have been recorded. Like most sparrows, their plumage features stripes in shades of brown, gray, and black that blend in well with their grassy environments. Known predators on adults and nests include northern harriers, short-eared owls, fish crows, Norway rats, and garter snakes. Though not confirmed, suspected predators include herons, egrets, glossy ibises, American crows, and black snakes.
Known Predators:
Anti-predator Adaptations: cryptic
Male sexual behavior is a form of “scramble competition polygyny”. Males will actively survey an area in search for females. Once a female is found, the male will intercept them and attempt to copulate with the female, which is usually a forced mating. One to several males may attempt to mate with a single female at one time, or several males may mate with a single female one after the other in a short period of time. This breeding method suggests that sperm competition is an important factor in this species. Although mating is forced by the male, receptive females will perform a mating invitation display during the time she is building a nest. She will crouch with her tail and bill raised, wings folded and slightly raised, and make no vocalizations.
Mating System: polygynous
Ammodramus nelsoni breeds annually during the spring and summer months. Females construct a cup-shaped nest attached to low-lying reeds or willow branches. Location of the nest is critical in habitats where water levels fluctuate, and females must select a height at which nests will not be flooded. Clutches of three to seven eggs are laid in late spring or early summer. The eggs hatch after about 11 days of incubation and 10 days later, the young are able to leave the nest. The young receive continued care from the female for an additional 20 days after fledging, when they become independent.
Breeding interval: Nelson's sharp-tailed sparrows produce one brood a year.
Breeding season: Nelson's sharp-tailed sparrows breed in late spring or early summer
Range eggs per season: 3 to 7.
Average eggs per season: 3 to 5.
Average time to hatching: 11 days.
Range fledging age: 8 to 11 days.
Average time to independence: 1 months.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous
Females alone build the nest and incubate the eggs. Initially the female broods the nestlings frequently after hatching and then less frequently after 4 to 5 days. Brooding episodes may last up to 14 minutes, but usually are 2 to 6 minutes. Female Nelson's sharp-tailed sparrows do not defend the nest if a predator is nearby. They fly off the nest and stay quiet and hidden nearby. When the nestlings are in the fledgling stage, females will give alarm calls to warn their offspring of predators.
There is very limited data on nestling feeding. It has been observed that young feed almost exclusively on invertebrate prey. Food items are mostly found by the mother in nearby vegetation, mud and water. The male has been observed to occasionally bring food to the nest. Fledgelings remain near their mother who continues to care for them for 20 days post-fledging.
Parental Investment: altricial ; female parental care ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female); pre-weaning/fledging (Provisioning: Female); pre-independence (Provisioning: Female)
Nelson's sparrow (Ammospiza nelsoni) is a small New World sparrow.
This bird was named after Edward William Nelson, an American naturalist. Formerly, this bird and the saltmarsh sparrow (Ammospiza caudacuta) were considered to be a single species, the sharp-tailed sparrow; because of this it was briefly known as Nelson's sharp-tailed sparrow.
Measurements:[2]
Adults have brownish upperparts with gray on the crown and nape, a cream-colored breast with light or indistinct streaking and a white throat and belly; they have an orange face with gray cheeks and a short pointed tail.
Their breeding habitat is marshes on the Atlantic coast of Canada and Maine, central Canada, (the Canadian Prairies region and a coastal strip on the south of Hudson Bay), and the north-central United States.
These birds migrate to the southeastern coast of the United States. They forage on the ground or in marsh vegetation, sometimes probing in mud and eat mainly insects, aquatic invertebrates and seeds. Their call is a raspy trill, almost a mechanical sound. It may be given in flight during the nesting season. The sound has been likened to a drop of water hitting a hot fry pan.
Males compete for females but do not defend territories; they sometimes help feed the young. Mating is largely promiscuous by both sexes; multiple paternity in a nest is common. The nest is an open cup attached to vegetation and close to the ground. Due to their proximity to the ground, they are vulnerable to habitat loss and are at risk due to rising sea levels.[3]
Nelson's sparrow (Ammospiza nelsoni) is a small New World sparrow.
