Bohemian Waxwings Selectively Feeding on the Stamens of Silver Maple Winnie Poon

Bohemian Waxwings Selectively Feeding on the Stamens of Silver Maple Winnie Poon

165 Bohemian Waxwings selectively feeding on the stamens of Silver Maple Winnie Poon Introduction cast 2007-2008 (Pittaway 2007). At the In the winter 2007-2008, Ontario expe - same time, a massive crop failure of the rienced its largest winter finch irruption native Mountain Ash ( Sorbus decora ), in the last ten years. Many boreal finches also occurred across much of northern irrupted well south of their normal Ontario. Mountain Ash berries normally ranges, following the largest coniferous provide an important winter food for and deciduous tree seed crop failure in a Bohemian Waxwings ( Bombycilla garru - decade across the boreal forests in much lus ) across boreal regions of Canada, but of Ontario and western Quebec. This the 2007 crop failure evidently precipi - event unfolded exactly as forecasted by tated another irruption of this species Ron Pittaway in his Winter Finch Fore- across eastern North America. Figure 1. Location where the Bohemian Waxwings were seen feeding; the flowering Silver Maple is nearest the picnic table. Alden Road, Markham, York , 8 April 2008. Photo: Winnie Poon VOLUME 26 NUMBER 3 166 This irruption turned out to be the Markham, York Regional Municipality. largest ever recorded in the Greater The waxwings were reported to be feed - Toronto Area (GTA) and adjacent south - ing on “fallen shoots”, and also “newly ern Ontario (Poon 2008). It lasted from opened shoots” on the trees. Intrigued by approximately mid-October 2007 to the this report and being curious as to what third week of April 2008. It was very the “shoots” would look like, Roy Smith extensive in terms of bird numbers, geo - and I arrived on site on 5 April for a clos - graphic area covered and duration. With - er look. in the GTA, it surpassed the previous There were already six other birders record of 1999-2000, and even the influx enjoying the bird activities when we of 1958-1959, which Gunn (1959) des - arrived at 1420 h. The location was the cribed as “the largest of the century”. front lawn of a small industrial building But the most notable feature of the on the southeast corner (Mactec Canada 2007-2008 irruption was the returning – 555 Alden Road) (Figure 1). Close to wave of waxwings in spring, that resulted the front door of the building was a 7 – 8 in an unprecedented number of April m tall Silver Maple ( Acer saccharinum ) in records for the GTA, especially within full blossom. There were two other small - the City of Toronto. The number of er maple trees about 10m north, but both records in the database of the Toronto had wilting blossoms. Around the north - Ornithological Club reached 48, whereas east corner, at the back of the side yard, only eight previous years had April was a row of four very thin Highbush records, and then only 1 to 3 each. It is Cranberry ( Viburnum opulus ) bushes acknowledged that the database may be that were devoid of berries, except for incomplete for some earlier years. It was some fallen ones on the lawn beneath. during this returning wave that the Most of the winter snow had melted, apparently rarely seen feeding behaviour leaving about 5% of patchy snow cover of Bohemian Waxwings eating the sta - on the lawns, and exposing the fallen mens of a Silver Maple tree ( Acer sacchar - fruits as noted. Lining the sides of the inum ) was recorded. lawn were 6 small, bare ash trees. Also, across Alden Road were seven other simi - Circumstances lar maples in bloom. On 3 April 2008, Siegmar Bodach posted We counted at least 38 Bohemian to ONTBIRDS (the listserve of the Waxwings, but no Cedar Waxwings. The Ontario Field Ornithologists) that a majority were feeding actively on the one flock of about 35 Bohemian Waxwings Silver Maple at the front door, but not on and 9 Cedar Waxwings ( Bombycilla the other maples in the area. Sometimes a cedrorum ) had been seen near the inter - group would perch on one of the smaller section of Alden Road and Hood Road in bare ash trees, perceivably resting after a ONTARIO BIRDS DECEMBER 2008 167 good meal, while several times these that the birds might be after the pollen birds flew down to a manhole cover near - instead. I investigated further using my by and drank from melt water that had telescope, concentrating on one feeding collected there (Figure 2). At times, a few waxwing. The bird appeared to be pluck - birds would split off and fly to the High - ing off and eating only the stamens, leav - bush Cranberry bushes, dropping to the ing the small red petals intact on the ground to eat the remaining fallen fruits. flowers that it was feeding on. It required All the birders were about 8-10m much concentration and time to see the from the maple tree and waxwings which bird swiftly plucking off the stamens, were pecking incessantly at what app - even with the help of a scope at close dis - eared to be clusters of tiny reddish buds tance. At this point, I digiscoped many on the branches. Using binoculars, I photographs of a feeding bird, including could see that the birds were not pluck - two series of continuous burst mode ing off and consuming the buds, but photos. Afterwards, by examining one of instead were just dipping their bills into these series frame by frame, I was able to the buds. I examined closely a clump of confirm that the bird was eating only the these buds in my hand, and was surprised stamens (filaments and anthers), while to find that from each tiny bud (flower) the outer parts of the flowers remained were many long and thin filaments (sta - untouched from the first frame to the last mens) with richly laden yellow pollen (Figure 4). These photos provide materi - pods at the tips (anthers) (Figure 3). al evidence of the Bohemian Waxwing Each clump was a mass of newly consuming stamens from a Silver Maple opened maple flowers and I suspected tree in spring. Figure 2. Nine Bohemian Waxwings drinking from meltwater on manhole cover at Markham, York , 5 April 2008. Photo: Winnie Poon VOLUME 26 NUMBER 3 168 Discussion In winter, Bohemian Waxwings are pri - marily berry and fruit-eaters, utilizing a wide variety of fruits for their winter sur - vival. In Ontario, some of these fruits are Mountain Ash, crab-apple ( Malus sp .), buckthorn ( Rhamnus sp .) , juniper ( Juni - perus sp .), bittersweet ( Celastrus sp. ), dogwood ( Cornus sp. ), and Highbush Cranberry. When available, Bohemian Waxwings may also feed on protein-rich insects (Witmer 2002) and tree buds, including American Elm ( Ulmus ameri - cana ) and ash ( Fraxinus sp.) (Pittaway 1990), as well as maple ( Acer sp.) (Elder 2002). Figure 4. Bohemian Waxwing feeding on the maple tree, note that the bird has three anthers in its bill and that most of the stamens have been nipped off the flowers directly in front of it. Markham, York , 5 April 2008. Photo: Winnie Poon ONTARIO BIRDS DECEMBER 2008 169 Figure 3. Clusters of blooming Silver Maple flower. Each flower had at least 14 -15 stamens with extremely long filaments. The anthers were large and reddish-yellow in color when fresh. Markham, York, 8 April 2008. Photo: Winnie Poon During spring, the waxwings may also may have been observed before. Bent feed on sap drips from maple and birch (1950) quoted Swarth (1922) that (Betula sp.) trees (Bent 1950). However, Bohemian Waxwings “...were seen feed - for North Am er ica, there seems to be no ing on insects and also on berries and published record of Bohemian Wax - other vegetable matter”. Although this wings selectively consuming flower sta - quote may be suggestive, there is no spe - mens, despite the possibility that this cific mention of this species consuming VOLUME 26 NUMBER 3 170 flower parts in Bent's account. Witmer apple, pear, cherry, oak, maple and ash, (2002) also quoted from Bent (1950) and it doubtless eats stamens of many that the Bohemian Waxwing “often feeds other varieties”. But for Bohemian Wax - on flowers of trees and shrubs in spring”. wing, Barrows only noted that “...this It is possible that Witmer drew the above bird feeds mainly on the same berries, quote from Bent’s account of the Cedar seeds and fruits as the Cedar-bird...”. Waxwing, since it is commonly accepted More recent studies on the Cedar that the two North American species of Waxwing found that flowers, including waxwings share similar dietary and feed - stamens, comprised only 4% of the ing habits. Undoubtedly, Bohemian annual diet, but in May, when fruits are Waxwings have often been seen eating scarce, they could amount to 44% of the the same foods as Cedar Waxwings, and diet (Witmer 1996). Flower petals may it seems logical to assume that the results provide sugars, while pollen on stamens of certain studies of Cedar Waxwings can provides protein. Consumption of plant be extrapolated to Bohemian Waxwings species that do not have showy petals or as well. nectar rewards ( Acer , oaks — Quercus , Bent’s account of the Cedar Waxwing and poplars — Populus ) indicated that contains a number of statements with the waxwings were partly motivated to regard to flower consumption; including consume pollen. Witmer also observed the following: that Cedar Waxwings ate the staminate I “The only other vegetable food of cat kins of Eastern Cottonwoods ( Populus importance in the diet of the Cedar- deltoides ) in combination with Highbush bird is flowers” Cranberry in spring, this observation I “At New Orleans...about Feb.1, when subsequently led to his conclusion that it arrives to feed on the fruit of hack - this diet-mixing behaviour was a strate - berry and Japan privet, and the flow - gic choice for the waxwings at that time ers of the elm.

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