Ipswich sparrow

There are 17 recognized subspecies of the savannah sparrow. The driving force behind determining these subspecies is called natal philopatry. Natal philopatry is the tendency of savannah sparrows to return each year to the area where they were hatched. Subspecies are considered reproductively isolated. This tendency is particularly strong in island species, such as the Ipswich sparrow.

In New Jersey, the Ipswich sparrow uses the coast as wintering grounds. They breed exclusively on Sable Island, Nova Scotia. Leaving their mid-Atlantic wintering grounds in March, they arrive on the island in early April. Spending almost 7 months on Sable Island, they migrate south in mid-October. Males typically winter further north than females. Ipswich sparrows also winter in other mid-Atlantic coastal states. Occasionally, they winter as far south as the Carolinas.

The Ipswich sparrow nests and winters in very similar habitat. They prefer coastal dunes with more stabilized areas when nesting. They avoid the back dunes of beaches. In the winter months, they prefer areas with good grass cover and access to fresh water.

The Ipswich sparrow feeds along shoreline habitat alone or in small flocks in non-breeding months. They typically walk when hunting instead of hopping as their continental counterparts would. They hunt for insects, insect larvae, and other small arthropods all while walking on the ground. During the winter months, seed is a particularly important food source.

Male Ipswich sparrows arrive on their breeding grounds well ahead of females. When the females arrive, males perform courtship singing and flutter flights. If a pair has nested together in previous seasons, they will begin breeding more rapidly than unknown mates. Ipswich females choose the nest site and begin to build a ground nest alone. It takes her 1 to 3 days to build a nest that has an outer layer of course grasses and a tightly woven inner cup of fine grasses.

The first egg is laid as soon as the nest is complete. The female lays an egg once per day until she has a 2-6 egg clutch. The egg color of Ipswich sparrows varies from pale green and brown to off-white, with marked brown speckling. Only the female incubates the clutch for 12-13 days.

The young are helpless when hatched and both parents bring food back to the nest to feed them. Fledglings leave the nest at 11 days. However, the adults continue to care for them until 21 days of age. Adult females may be incubating a second clutch while still caring for a first brood. Ipswich sparrows will breed continually throughout the season, having up to 3 broods in one breeding season. Juveniles form loose flocks and delay migration for 2-3 months post-fledging. They are sexually mature at 1 year of age.

In New Jersey, the Ipswich sparrow is listed as a species of Special Concern. They are presently listed as partial status under the Endangered Species Act. This partial status indicates that the status applies only to a portion of the species’ range.

The Ipswich sparrow is of particular importance because of their high reproductive rate during the breeding season. The protection of barrier islands, dune grass, and other open coastal habitat is necessary to help this species thrive. Natal philopatry also plays an important role in conservation. With their breeding range limited to one island, it is of great importance to protect that island and its resources.