Male robin carrying mouthful of earthworms. Photo by Dow Lambert
“Time to Wake Up,” said the Robin
by Bob Boekelheide
It’s robin season, time when American Robins belt out their dawn chorus outside our bedroom windows. Wow – they sure are loud! Robins are “Big-eyed Birds,” able to perceive low light levels and start singing in the pre-dawn twilight. Most mornings they start their songs almost an hour before sunrise, playing their role as nature’s alarm clock. Once they’ve established their territories, males might serenade for only a few minutes each morning, then they turn over the sound stage to other species. They often sing longer if it’s a dark day with solid overcast, and they might even start singing again if it clouds up and gets darker at mid-day.
Adult male American Robin. Photo by Bob Boekelheide
Even though robins’ songs are the harbinger of spring, robins are common year-round birds on the north Olympic Peninsula. Data from the Wednesday morning bird walks in Railroad Bridge Park show that robins in the Sequim lowlands actually have a distinct annual cycle, with high detections in fall and again in late winter, then declining through the nesting season to an annual low point in August. Many of our robin detections in spring are singing males on territories. By July and August, males have stopped singing, the last chicks have fledged, and it’s time for the adults’ annual molt, when they choose to hide out and avoid predators. Therefore, we detect fewer robins in August, but is it just because they become quiet and stealthy?
Outside the nesting season, robin distribution is all about food, particularly fruits, berries, insects, and earthworms. They become nomads, often traveling around in large flocks looking for food concentrations. In fall and winter, one of the biggest attractions for robins in the Sequim area is hawthorn fruits hanging from trees along Jamestown Road, where we sometimes tally thousands of robins on the Christmas Bird Count. Fruiting madronas, mountain ash, hollies, and unpicked fruit trees also entice winter robins around here.
Equally important for winter robins are protective roosting sites, often in dense stands of conifers or evergreen shrubs. It’s nice if the roosts are located near feeding sources, but not essential. In Yakima, WA, where old unpicked apples provide food in fall and winter, thousands of robins sometimes use roosting sites in town, then fly several miles to apple orchards in the countryside.
The robin peak in February is different. By that time the fruits are long gone, yet large flocks of robins move around the area, particularly males. Late winter birds, likely the vanguard of spring migration, spend a lot of time hunting earthworms on lawns and fields, sometimes congregating by the hundreds where picking is good. Spring rains aid in the hunt, bringing earthworms to the surface for ease of capture.
American Robin is clearly one of the most numerous and widespread bird species in North America, breeding across much of subarctic Canada, the U.S., and highlands in northern Mexico. It’s been said that American Robin is the most abundant bird in North America, with numbers estimated between 320 to 380 million robins. This seems like a huge number, which it is, but ironically it is probably a little less than the total number of humans in North America. It is sobering to think that the most abundant bird species in North America numbers less than the number of humans in North America.
What is the secret to their success? American Robin is one species that thrives with or without humans. The introduction and spread of nightcrawlers and angleworms, neither of which is native to North America, as well as the widespread planting of fruit trees across the continent, undoubtedly helped robins. Wherever goes Johny Appleseed, there goes the robin.
Male robin carrying a mouthful of earthworms. Photo by Dow Lambert
How are local robin populations doing? We have three data sets that might provide the answer: Wednesday morning bird walks at RR Bridge Park, Christmas Bird Count data, and eBird Status and Trends.
A graph of the yearly changes in American Robins counted on Wednesday morning bird walks in RR Bridge Park (Figure 2) shows a slight increase in robins over the last 23 years. Notice that the variability, measured here by standard deviation, is largest in the years with high counts of robins, such as 2009 and 2015, whereas it is often lowest during years with low counts of robins, such as 2011, 2013, and 2019. This is partly because during big robin years we often see large flocks of robins flying over the park, particularly in the fall. When a big flock of several hundred robins flies over it causes a great deal of variability to average numbers.
How about robin numbers during the last 30 Christmas Bird Counts? CBC data are more difficult to interpret, because CBCs only occur on one day each year. That one day could be sunny and calm with great viewing conditions, or it could be snowy, windy, and hard to find birds. We try to be consistent with our robin tallies each year, but their numbers fluctuate a lot, as seen in Figure 3. The highest years -- 2002, 2004, and 2017 – were all years when our observers recorded thousands of robins eating hawthorn berries along Jamestown Road. One particularly low year – 2010 – had easterly winds gusting to 40 mph all day, with low counts of many species, not only robins. Regardless, the general trend on the graph is upwards, similar to the trend at RR Bridge Park.
Lastly, if you’d like to check changes in robin numbers using eBird, first open the eBird homepage, click the “Science” tab at the top, then click on “eBird Status and Trends,” next enter American Robin in the species name box, and finally click on “Trends.” The map shows relative changes in robin numbers in North America for the period 2012 to 2022, including the north Olympic Peninsula. For the entire state of Washington, the trend is basically flat, with a miniscule increase of 0.2 percent, showing little change in robin numbers. For the lowlands around Port Angeles and Sequim, the trend is slightly decreasing, but not significantly different than zero. Curiously, much of the area around the Puget Sound lowlands shows a significant downward trend of about 10 to 15 percent, which stands out as one of the largest areas with decreases in western North America. Another area with decreasing trends is the upper Midwest, including Illinois, Indiana, Wisconsin, and Michigan. Conversely, robin numbers appear to be increasing within a large area in British Columbia and Alberta.
This is the time to closely watch nesting robins in your neighborhoods and nearby forests. Their nests are fairly easy to find if you follow them as they carry food to their chicks. Usually placed in the crotch of a tree or branch, the nest has a foundation of small sticks and grasses, then shaped by the female using mud from worm castings, and finally lined with finer grasses to make the bowl of the nest.
Robin eggs are noteworthy for their intense blue color, usually without blotches or other markings. One study showed that the vivid blue color may stimulate males to provision chicks more than if the chicks came from paler eggs. Another advantage is that robins are apparently able to immediately recognize the difference between their eggs and the eggs of parasitic Brown-headed Cowbirds, which are white with lots of spots. Robins readily toss cowbird eggs out of their nests, or else puncture them in the nest.
Blue robin eggs in a nest built in a colander hung on Gary Bullock’s patio. Photo by Gary Bullock
A typical robin clutch usually only has three or four eggs, rarely five. Incubation periods are short: the time from laying the last egg to hatching takes 12 to 14 days. The chicks are out of the nest in another 13 days, but not able to fly or feed on their own for a few more days. The adults, particularly the male, continues feeding the fledglings for several days out of the nest.
Robins regularly lay a second clutch, but rarely a third. Did I mention that it happens very quick? Most robins in North America first lay eggs in April and May, then they are finished with nesting by late June and July. Just enough time for two clutches.
Fledgling robins look quite different than adults, with telltale spots on their breast that belies their thrush heritage. They undergo a body molt within a few months of fledging, when they lose their spots and begin to look like normal adult robins. The young birds mature very quickly, as most robins begin nesting in their first year after fledging.
Fledgling American Robin showing its spotty breast. Photo by Bob Boekelheide.
Similar to other surface-nesting passerines, it’s a tough world out there for nesting robins. On average, more than half of all robin nests fail to produce chicks. As a consequence of nest losses, the number of young fledged per attempted nest averages only about one chick per nest.
Each breeding bird is different, of course. Some do everything right yet still lose their eggs to predation. Some are lucky and fledge lots of chicks. During a three-year study in Madison, WI, one super female laid a total of 30 eggs, hatched 21 eggs, and fledged 16 chicks. It’s likely that some very successful birds like this female help keep their populations afloat, winners in the battle of natural selection.
American Robin nesting in an old colander hanging under Gary Bullock’s patio. Photo by Gary Bullock.
How long to robins live? The oldest banded robin lived almost 14 years in the wild. As always, this is exceedingly rare. Based on other banding records, if a young robin survives to the end of its first winter, it only lives another 1.7 years on average. Very few adult robins survive past their sixth year.
American Robin with a tick embedded in its cheek below its eye. Photo by Bob Boekelheide
It is easy to take robins for granted, since they are so common and we see them every day. I encourage you to take the time to watch them closely and look deeper into the lives of these wonderful birds.
Many of the interesting facts about American Robins in this story came from Birds of the World, an on-line resource available through Cornell Lab of Ornithology. I highly recommend that all bird aficionados subscribe to Birds of the World, both for the information and to support the Lab of Ornithology.