The Evening Grosbeak is a striking bird with its bright yellow and black plumage. These medium-sized finches breed across Canada and the western United States, then head south for the winter in highly variable numbers. So do Evening Grosbeaks stay all winter in some parts of their range? Let’s take a look at the facts.
When do Evening Grosbeaks migrate?
Evening Grosbeaks are irruptive winter migrants. This means their migration habits vary greatly from year to year depending on food supplies. In years when tree seed crops are plentiful farther north, most Evening Grosbeaks may stay in Canada and the northern tier of U.S. states all winter. However, when food is scarce, they will migrate south in big numbers, sometimes as far as the Gulf Coast states.
Evening Grosbeaks begin migrating south in September and October. Migration peaks in November. Usually the bulk of the population winters across the northern U.S. and southern Canada. However, major flights occur in some years. For example, in the winter of 2020-2021, Evening Grosbeaks were reported as far south as Texas and Florida due to poor seed crops farther north.
Where do Evening Grosbeaks winter?
The core winter range of Evening Grosbeaks extends from southern British Columbia east to Quebec, and south to the Pacific Northwest, Great Lakes region and New England. However, as noted above, in years of food shortages they will wander much farther south. They have been recorded as winter vagrants to every state in the lower 48.
In mild winters, Evening Grosbeaks commonly spend the entire season in Canada and the northern Border States. For example, they are resident all winter in southern Ontario, northern Minnesota, northern Michigan, New York and northern New England. Further south they are more irregular in winter, only appearing in big flight years.
What impacts Evening Grosbeak winter movements?
Food availability is the key factor governing Evening Grosbeak winter movements. Being irruptive migrants, they will wander far and wide in search of ample food. Their winter diet relies heavily on seeds from trees such as maple, ash, elm, and boxelder. When these trees produce a bountiful seed crop farther north, grosbeaks are more likely to stay put. When the seed crop fails, they migrate south in large flocks.
Other factors can also influence their migration patterns. Colder winters may encourage larger numbers to move south. Also, breeding success and population levels may impact winter distribution to some degree. All of these factors interact in complex ways to determine Evening Grosbeak winter movements in any given year.
Do Evening Grosbeaks stay in flocks?
Yes, Evening Grosbeaks are highly social and usually remain in flocks all winter. These flocks may consist of a dozen or so birds up to 100 or more. Males and females mingle freely in winter flocks. Younger birds also join these flocks after they finish breeding.
Staying in flocks improves the grosbeaks’ ability to find patchy food supplies in winter. Many eyes looking for food makes their nomadic lifestyle easier. These flocks will often show up suddenly when a food bonanza is found, then disappear just as quickly. Flock members communicate with a variety of chattering calls to keep in contact.
What do Evening Grosbeaks eat in winter?
As mentioned above, tree seeds provide the bulk of Evening Grosbeak nutrition in winter. They use their strong thick bills to crack open seeds. Favorites include maple, ash, birch, elm, poplar, willow and boxelder seeds. They will also visit feeders for sunflower seeds, especially if natural foods are scarce.
Besides seeds, Evening Grosbeaks also eat some buds, fruits and berries in winter. Common winter fare includes dogwood, mountain ash, buckthorn, sumac, rose hips and sometimes honeysuckle berries. Insects provide protein during the breeding season but not in winter.
How do Evening Grosbeaks find food in winter?
Evening Grosbeaks are nomadic in winter, wandering both locally and regionally in search of patches of trees and shrubs holding good seed crops. They often follow each other, forming flocks that can descend suddenly on a fruitful feeding area. Then these flocks quickly move on once the area is depleted.
Their strong bills allow them to crack open seeds other birds can’t access. Males can crack seeds 3 x thicker than a human’s hand bones! This gives Evening Grosbeaks an advantage over other winter finches. Their bright plumage and loud calls also help keep flock members in visual and vocal contact when feeding.
What is an irruption of Evening Grosbeaks?
An irruption is an irregular migration event where birds appear in unusually large numbers far outside their normal range. Evening Grosbeaks are famous for their periodic winter irruptions farther south when boreal seed crops fail.
These irruptions are unpredictable and highly variable. In one year, Evening Grosbeaks may stay north all winter. The next year they could irrupt down to the southern U.S. or even Mexico in huge numbers. Their mobility allows them to take advantage of locally abundant food supplies.
Are Evening Grosbeak irruptions becoming less common?
Decade | Major Irruptions |
---|---|
1900s | 1909-10, 1916-17, 1926-27 |
1910s | 1916-17 |
1920s | 1926-27 |
1930s | 1939-40 |
1940s | 1946-47, 1948-49 |
1950s | 1952-53, 1957-58, 1959-60 |
1960s | 1963-64, 1968-69 |
1970s | 1972-73, 1977-78 |
1980s | 1980-81, 1985-86, 1988-89 |
1990s | 1991-92, 1997-98 |
2000s | 2002-03, 2008-09 |
2010s | 2013-14 |
Records show Evening Grosbeaks used to stage major winter irruptions south about every two to four years prior to the 1980s. However, in recent decades these irruptions have become less frequent. For example, between 2000 and 2018 there was just a single major incursion in winter 2002-03.
The reasons for this change are not fully understood, but may relate to climate factors impacting boreal seed crops. Some experts worry the reduced irruptions are tied to an ongoing decline in Evening Grosbeak populations due to habitat loss.
Why are Evening Grosbeaks declining?
Evening Grosbeaks have declined significantly since the late 1980s, both in total population and their winter range. The causes are not fully clear, but likely include:
- Habitat loss in boreal forests where they breed
- Reduced spruce budworm outbreaks decreasing food supplies
- Increasing competition for seeds from growingfinch populations
- High mortality of young birds, potentially from disease or predators
Unfortunately, reduced irruptions south may be a warning sign of this decline. Evening Grosbeaks were listed as a Species of Special Concern in a number of eastern provinces in the late 2000s.
Where can I see Evening Grosbeaks in winter?
Here are some top locations for finding wintering Evening Grosbeaks during irruption years when the birds move south of their core range:
- Central park and other parks in New York City
- Western Massachusetts
- Altamont, New York
- Northern Pennsylvania
- Northwest Ohio
- Southern Ontario near Lake Erie and Lake Ontario
- Central Minnesota
- Black Hills of South Dakota
- Northern Idaho and Western Montana
- Eastern Washington and Oregon
However, almost any location could see Evening Grosbeaks in a major irruption year. Backyard bird feeders in winter are their most reliable sites, especially if stocked with sunflower seeds. Parking a car under fruiting trees and waiting for a flock is another good watching technique.
Interesting Facts about Evening Grosbeaks
- The Evening Grosbeak is the only member of its genus Coccothraustes, which comes from Greek words meaning “kernel breaker”.
- Their bright yellow feathers take on an olive-green tinge by late summer due to feather wear and pigment changes.
- During courtship, the male Evening Grosbeak makes an elaborate display while perched, fanning his tail and erecting his body feathers.
- Both parents feed the nestlings; the male by regurgitating seeds, and the female by regurgitating insects.
- Their nests are flimsy piles of twigs relatively low in conifers, often taking over an old squirrel or bird nest.
- Evening Grosbeaks often reuse the same nesting territories in successive years, especially sites near spruce budworm outbreaks.
- Young Evening Grosbeaks may continue begging behavior through early winter, loudly soliciting feeding from adults in the flock.
- Peak numbers of Evening Grosbeaks are often recorded as they pass south through Ontario from late October to late November.
- Irruptive flocks numbering thousands of Evening Grosbeaks were recorded in the eastern U.S. in the late 1800s, decades before Christmas Bird Counts started.
- In bill structure, Evening Grosbeaks are intermediate between strictly seed-eating finches and grosbeaks that also eat buds and shoots.
Conclusion
To summarize key points:
- Evening Grosbeaks are irruptive winter migrants, with large southward movements in some years.
- They often remain through winter across southern Canada and the northern U.S., especially in mild seasons.
- Major irruptions now occur less frequently, potentially signaling a population decline.
- Evening Grosbeaks rely on tree seeds for winter food, making them vulnerable to crop failures.
- Their nomadic flocks follow changing food supplies, often over long distances.
- Highly social, Evening Grosbeaks remain in noisy flocks all winter for feeding and roosting.
So while Evening Grosbeaks no longer stage massive southern flights every few years, they continue to brighten boreal winter days with their big bills, bold colors, and boisterous behavior. Birders able to accommodate their unpredictable wanderings may be rewarded with a splash of summer in the snow.