Montana Field Guide

Nonbreeding plumage (September-March) is black and white. The head is topped with a gray crown bordering on white cheeks; this border extending in a rather straight line from behind the eyes. The front of the neck, flanks and belly are dingy white. In breeding plumage, the neck and flanks are ruddy in color, the crown and cheeks are black and a stripe of white to gold feathers extends back from the eye.

For a comprehensive review of the conservation status, habitat use, and ecology of this and other Montana bird species, please see Marks et al. 2016, Birds of Montana.

Most easily confused with the Eared Grebe, but differs from this species by having the forehead rise to a peak at the rear of the crown rather than in the middle (as with the Eared), a thicker neck and thicker bill with the lower mandible lacking an up-turned tip (all features of Eared Grebes), and a less rounded back without the fluffier rear-end. Eared Grebe also lacks the whitish patch at the base of the forewing that are visible in flight.

Migratory. Present throughout the year, but only in small numbers during winter. Spring arrival appears to occur during late March to early May, autumn departure in October and November (Saunders 1921, Montana Bird Distribution Committee 2012). Arrival dates for western Montana are 31 March to 29 April (Hand 1969). At Fortine, spring arrival averages 25 April, and ranges from 4 April to 9 May (Weydemeyer 1973). At Bozeman, spring arrival averages about 21 April (12 April the earliest record), with peaks about 26 April and gone by 1 June; autumn movement begins about 8 September, peaks around 3 November, and ends around 20 November (Skaar 1969).

Horned Grebes use shallow freshwater ponds and marshes with beds of emergent vegetation (especially sedges, rushes and cattails), including in Montana (Dubois 1919, Weydemeyer 1932). In spring and fall the Horned Grebe is found mainly on large sized bodies of water, including rivers and small lakes. The winter range consists of large sized bodies of fresh and more commonly salt water; usually inshore (Stedman 2000).

The Horned Grebe feeds on aquatic arthropods in the summer; and fish and crustaceans in winter, especially amphipods, crayfish, and polychaetes (Stedman 2000). Occupies Lincoln County, Montana ponds and lakes without fish during the breeding season (Weydemeyer 1932).

BBS is not suitable for monitoring this species in Montana; there were significant survey-wide declines of 2.7% per year during 1966-2009 and 2.9% per year during 1999-2009. Reported 24 of 31 winters on Montana Christmas Bird Counts (CBC) during 1979-80 to 2009-10, from both sides of the Continental Divide but usually in the western half of the state; high total number was 73 (0.0318/party hour) on three counts in 2009-10. Mean annual CBC totals for all other winters when reported (n = 23) was 5.8, with only three of those reporting as many as10 to 12 individuals. No obvious trend is evident, although years reporting no Horned Grebes occurred prior to winter 1993-94; the winter of 2009-10 is anomolous relative to all prior winters.

The Horned Grebe breeds on small ponds, potholes, and lake inlets containing a mixture of emergent vegetation and open water. In Lincoln County, Montana, reported only on rush-grown lakes (Weydemeyer 1932) and in flooded grasslands of Teton County (Dubois 1919). The floating nest is usually concealed in the vegetation. The Horned Grebe is intensely territorial and usually nests alone or occasionally in small colonies. The young are fed and warmed by a parent for a few days after hatching (Stedman 2000). In Montana, nests have been reported 28 May to 18 July, young 12 July to 25 August (Dubois 1919, Saunders 1921, Weydemeyer 1975, Montana Bird Distribution Committee 2012); one nest contained 6 eggs on 12 June.

Stable water levels are important for nest success and brood rearing. Any conservation efforts in wetland habitats should prove beneficial to this species. Implementation of a state-wide colonial waterbird monitoring program should be part of any management effort (Casey 2000).

Greatest threats include wetland drainage, fluctuating water levels and chemical contaminants at breeding areas, oil spills and pesticide accumulation during winter.