Townsend's Storm-Petrel or Ashy Storm-Petrel?

Here's how to tell the difference

Townsend's Storm-Petrel image 1

Townsend's Storm-Petrel

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Ashy Storm-Petrel image 1

Ashy Storm-Petrel

Townsend's Storm-Petrel

Hydrobates socorroensis

Townsend's Storm-Petrel Recognition Guide

1. General appearance: The Townsend's Storm-Petrel exhibits a compact body shape typical of the storm-petrels. Its plumage is predominantly sooty brown with a slightly paler rump and upper tail coverts. The wings are long and pointed, aiding in its graceful, fluttering flight often close to the water. The tail is squared at the tip. The beak is black and relatively short, while the feet are also black, with webbing between the toes. 2. Male vs female: Both male and female Townsend's Storm-Petrels are visually similar and do not exhibit significant sexual dimorphism. They share the same plumage pattern and coloration, making it challenging to distinguish between sexes based solely on physical traits in the field. 3. Juvenile: Juveniles closely resemble adults but may have slightly fresher and less worn plumage upon fledging. Juveniles exhibit the same sooty brown coloration and similar wing and tail shapes as the adults. As they mature, their plumage will gradually acquire a more consistent sheen, aligning closely with that of fully-grown birds. Behavioral differences, rather than plumage, are often more telling when identifying juveniles, as they can appear less experienced in flight techniques compared to adult birds.

Size

7.9 - 9.1 in/0.7 - 0.9 oz

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How to tell the Townsend's Storm-Petrel from the Ashy Storm-Petrel

Visual differences

Townsend's Storm-Petrel has a weight of 0.7-0.9 oz and a length of 7.9-9.1 inches, while Ashy Storm-Petrel is heavier at 1.2-1.9 oz with a length of 7.1-8.3 inches. Townsend's Storm-Petrel typically has darker plumage, while Ashy Storm-Petrel is known for its distinct smoky gray coloration. Both have sharp beaks suitable for snagging prey, but Townsend's may appear slightly sleeker. Their size and differing shades of gray are key visual markers for identification.

Key differences and behavior

Townsend's Storm-Petrel and Ashy Storm-Petrel display distinct behaviors and adaptations. Townsend's Storm-Petrel, found mainly in the northeastern Pacific near Baja California, exhibits a pelagic lifestyle, feeding on krill and small fish in offshore upwelling zones. In contrast, the Ashy Storm-Petrel prefers the coastal regions around California's Channel Islands, feeding closer to shore and occasionally following ships for scraps. Both species nest in rocky crevices, but Townsend's Storm-Petrel forms life-long pairs and breeds discreetly at night, whereas Ashy Storm-Petrels are monogamous for the season and mate primarily at sea. The latter also shelters nests by timing egg-laying to avoid predators. Townsend's Storm-Petrels weigh less (0.7-0.9 oz) compared to Ashy Storm-Petrels (1.2-1.9 oz), which affects their foraging strategies and range. Their shared adaptability to nocturnal habits aids their survival in diverse marine environments.

Still not sure? Here are more lookalikes!

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