According to Cornell's Allaboutbirds.org, the RBGB males have some interesting traits i.e.:
* Researchers used mounted specimens of male Rose-breasted Grosbeaks to explore aggressive behavior. Live male birds attacked the white rump and flanks of the models, suggesting that the white markings are more important than the red chest in stimulating aggression.
* Males sing to establish territories and attract females. When a female approaches, the male rebuffs her for a day or two before accepting her as a mate. Once mated, Rose-breasted Grosbeaks appear to be monogamous. A breeding pair will tolerate migrant males in their territory if the intruder is silent. Otherwise, territorial males ward off male intruders by spreading their tails, flicking their wings, raising their crown feathers, and often chasing the intruder away.
* The above was under the tab for life history along with several other interesting facts.
Vermont Birdhouses and Wood Products
Rutland Town, VT
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On Friday, May 9, 2014 6:34 PM, Kaye Danforth <[log in to unmask]> wrote:
Yes, it appears two males were just a wee larger, had stronger dark markings and larger, brighter red bibs. The other three weren't as strongly marked, and had thinner, less brilliant red bibs. They also appeared a bit smaller, but this might be due to having just flown in and needing to bulk up again. Odd to see all five ignoring the charms of the lady, not to mention not even a tussle between the five guys.
On May 9, 2014, at 3:49 PM, Jane Stein wrote:
> Same as my three! They're not "supposed" to do that, but clearly, they do.
> Do you notice any difference in the size of the red bibs?
> On 5/9/2014 2:20 PM, Kaye Danforth wrote:
>> Today my husband and I were enjoying coffee on the porch gawking at
>> FIVE male rose-breasted grosbeaks all serenely feasting side by side.
>> They were ignoring the female RBG perched on the armature connecting
>> the feeders, and clearly not moving over for her to join in. Below
>> were a pair of white-crowned sparrows racing around like road
>> runners. You never know what appear these these days! Kaye in
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