American Robin (Turdus migratorius) Gail McPeek
Troy, Oakland Co., MI. 5/7/2006. © Jerry McHale This species is sponsored in memory of Rose Craven.
(Click to view a comparison of Atlas I to II)
Michigan is one of three states which adopted even our northernmost land, Isle Royale, has breeding robins in all townships. the American Robin as its state bird. This large, red-breasted thrush is widely distributed and Obvious from the atlas map is the ease at which abundant across nearly all of North America. In participants could confirm breeding (67%). The Michigan, it is a common summer resident and adaptable, opportunistic robin coexists well with migrant, with lesser numbers overwintering in humans, providing ample opportunity to southern portions of the state and occasionally discover nests and observe the stubby-tailed, farther north. Even though some robins stay the speckle-breasted, newly-fledged young. winter, many people consider this bird to be the official “harbinger of spring.” Beginning Robins breed in a wide range of habitats across sometime in March, a steady stream of the state, including mature and early northbound migrants descends upon Michigan. successional forests, open woodlands, parks, Despite lingering snow, robins seem anxious to orchards, farms, and residential areas. During return to breed and serenade us with their the breeding season they are especially attracted “cheerily, cheer-up” song. to short-grass areas which offer an abundance of
earthworms and soft-bodied insects. Who Distribution hasn’t been entertained by a lawn-bobbing robin What Barrows (1912) described as, “probably tugging a reluctant worm from the soil? In our most abundant, best known and generally foraging studies, Eiserer (1980) found an best loved native bird,” still rings true today. overwhelming preference for short grass over The American Robin is number one on the long, and discovered that mowing increased most-reported species list, found in more foraging time as robins exploited temporarily townships than any other bird. Not surprisingly, vulnerable prey. results were nearly identical for MBBA I and
MBBA II, with robins recorded in 93% of Also important to robin distribution is the townships. Likewise, both atlases documented a presence of fruit-producing trees and shrubs. In similar statewide distribution across the three spring and summer, cherries, blackberries and major regions (SLP, NLP and UP). Occurrence mulberries are commonly eaten. Robins only drops off slightly from south to north, and
© 2011 Kalamazoo Nature Center American Robin (Turdus migratorius) Gail McPeek consume fruits year-round, but they become an Abundance and Population Trends increasingly greater proportion of their diet in (Click to view trends from the BBS) fall and winter. During lab feeding trials at Atlases do a good job of mapping where species Hope College in Michigan, Lepczyk et al. breed, but do not give us much information on (2000) found that robins prefer sugar-rich fruits abundance. More effort was made in MBBA II because of their simple and fast rate of to gather numbers of individuals during block digestion, but that lipid-rich fruits become more surveys. These observations show a general important by autumn. pattern of greatest abundance in the SLP, with progressively lesser numbers northward. In the Breeding Biology SLP, approximately 40% of the townships had Robins announce their arrival and establishment counts ranging from 46-200+ robins/block. In of breeding territories with persistent song. the NLP, most block totals were in the 1-45 They are one of the first species to sing in the range, with a small percentage in the 46-200 morning, and one of the last heard in evening. range. In the UP, the majority of blocks had 1- Both sexes sing (Wauer 1999), and though 16 robins recorded. similar in appearance, males tend to have blacker heads. Robins are strongly philopatric, To get an overall impression of just how meaning adults return to the same area year after abundant the American Robin is in Michigan, year, even the same nesting spot. Offspring also we can look at the PIF Landbird Population exhibit site fidelity, returning to their natal area Estimation Database. Using BBS counts from the following year. the 1990s, and extrapolating to total land area, the Michigan population estimate for the robin The heavy, mud-lined nest requires a sturdy tree is 5,900,000 (PIF 2007). Compare this to branch or other strong support. Human 3,600,000 Red-winged Blackbirds and structures are frequently used, making it easy to 3,400,000 European Starlings, the next two observe nesting activities. A large ladder stored highest species. Even with cautious under our deck has became prime robin real interpretation of these rough estimates, it is clear estate, providing ample opportunity to glimpse that the American Robin is Michigan’s most the 4-5 robin-blue eggs, the incubating female, abundant breeding bird. and the open-gaped mouths of hungry nestlings. Soon after the young fledge, the female is back Since the inception of BBS routes in 1966, in action constructing her second nest at the American Robins have shown a significant other end of the ladder. continuous increase across the continent (Sauer et al. 2008). In Michigan, route analysis for the Early arrival to the breeding grounds allows for 1966-85 period also found statistically 2-3 broods per season. The earliest recorded significant increases (Adams et al. 1988), from egg date for Michigan is 23 March. More an average of 45 robins/route in 1966-70 to 54 typically, first nests are in April to mid-May robins/route in 1981-85. Data since 1985, show with second nests in June to mid-July. The male a gradual continuation of this trend through the parent cares for the first brood while the female 1990s, and during MBBA II, robins averaged incubates the second clutch. Incredibly, second more than 60 birds/route in four of the six years broods can fledge five weeks after the first. (Sauer et al. 2008).
Wood (2006) reported similar annual increases in Wisconsin, and our eastern neighbor, Ontario, found a similar distribution between its two
© 2011 Kalamazoo Nature Center American Robin (Turdus migratorius) Gail McPeek atlases, and a stable to slightly increasing Breeding Birds in New York State. Cornell population (Burke 2007). Further east in New University Press. Ithaca, NY. York, second atlas results showed essentially Partners in Flight (PIF). 2007. PIF Landbird the same distribution of robins and a stable Population Estimates Database [web population (McGowan 2008). application]. Version 2004. Rocky Mountain Bird Observatory. Conservation Needs
© 2011 Kalamazoo Nature Center