Scent is unimportant for hummingbirds

[MBP]

Hello everybody,

There is a new scientific article which confirms the supposition that hummingbirds find their flowers mainly by sight, not by scent. Unfortunately, the article is not available for free, but here is the abstract:

Trends in floral scent chemistry in pollination syndromes: floral scent composition in hummingbird-pollinated taxa

JETTE T. KNUDSEN, LARS TOLLSTEN, INGA GROTH, GUNNAR BERGSTRÖM, ROBERT A. RAGUSO

Abstract

We studied an assemblage of 17 species of bird-pollinated Ecuadorian plants (from 14 angiosperm families), including taxa pollinated by short-billed (trochiline) and sickle-billed (hermit) hummingbirds. Hummingbirds are widely supposed to ignore fragrance while visiting flowers. We collected floral headspace odours in order to test the general prediction that specialist hummingbird-pollinated flowers are scentless. In nine out of 17 of these species we failed to detect any odours using gas chromatography-mass spectrometry (GC-MS), whereas the remaining eight species produced trace levels of volatile compounds. Most of these odour compounds were of terpenoid or lipoxygenase derivation and are commonly emitted by vegetative as well as floral plant tissues. Further studies will be required to determine whether these weak odours attract alternative pollinators, repel enemies or represent vestiges of a scented ancestry. © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society, 2004, 146, 191–199.

[emc]

Maybe that explains why they are attracted to the color red?

Hummingbird Magnets
http://www.cafepress.com/hummingbird2.14066573

[humminbird]

Most ornithologists seem to believe that very few species of birds have an olfactory system sufficiently developed for smell to play a significant role in their lives. The few exceptions that are pointed to in North America, Turkey Vulture, Black Vulture, California Condor and some of the pelagics that are known to "smell" land.

[Rasmus Boegh]

Actually, all research I have seen indicated that the two Condors, King Vulture & Black Vulture don't have any significant capability of detecting smell. In the new World Vultures it appears to be virtually restricted to the three members of the genus Cathartes (Turkey, Lesser Yellow-headed & Greater Yellow-headed Vulture). This probably being due to the fact that they need it in their habitat (often, but not always, dense forest or woodland), whereas the two Condors & Black Vultures prefer more open habitats where sight is much more usefull. The King Vulture is a special case and depend to a large degree on the three Cathartes. The Black Vulture behaves in a similar fashion in forested areas. Other species that have a significant olfactory sense are Kiwis and, as mentioned by "hummingbird", various seabirds (specifically Procellariiformes). This thread may be of interest (post#11 & 14 are specifically about the basically parasitic relationship between King/Black Vulture and Cathartes in forested habitats):

http://www.birdforum.net/showthread.php?t=17361

[MBP]

I have stumbled over another article, this time about the importance of colour to attract specific pollinators. Basically what the authors did was to exchange the information about how much yellow the flowers contain between two species of monkeyflowers, the pink flowering Mimulus lewisii, which is pollinated by bumblebees, and the red flowering M. cardinalis , pollinated by hummingbirds. What they got was a dark pink M. cardinalis, which was much more attractive to bumblebees (74-fold more visits), and a yellow-orange flowering M. lewisii with 68-fold more hummingbirds visits. Simultaneously, the altered flowers were less attractive to their original pollinators. It is not a complete evidence, but a good hint on how important the colour of a flower might be and how relatively easy a switch from one pollinator to another can happen in nature.

http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v426/n6963/full/nature02106_fs.html

H. D. BRADSHAW JR AND DOUGLAS W. SCHEMSKE
Allele substitution at a flower colour locus produces a pollinator shift in monkeyflowers
Nature 426, 176 - 178 (13 November 2003); doi:10.1038/nature02106

[krazyhorse]

well i use a more logical approach i had over 75 photographically documented rubies in my yard this year i attribute that to the 3 bright red vehicles that are parked in the driveway more than the flowers cuz i have a black thumb not a green one when it comes to the plants

[humminbird]

well i use a more logical approach i had over 75 photographically documented rubies in my yard this year i attribute that to the 3 bright red vehicles that are parked in the driveway more than the flowers cuz i have a black thumb not a green one when it comes to the plants

I too use the empirical evidence of what I and others see in our own gardens. When I see hummingbirds feeding on yellow, blue, white and purple flowers when there is a beautiful plant loaded with scarlet red flowers right next to it one day, then see them feeding on the scarlet red flowers and ignoring the others the next day, I conclude that the important factor is "does it look like food?" How else could one explain a hummingbird checking out the red Texas map on my license plate or the blue electric company seal on the meter? One can not deny the impact of red at certain times of the year though.

[krazyhorse]

something else i do with my feeders is i put yellow electrical marker tape on them mainly i have found that some of the hummers just like yelloew better than red, now if i could get one to sit down with me and have a caht about their personal preference in human talk it would make things easier to give them what they want but as of yet i have not found one will to sit down long enuff to see if they speak english

[humminbird]

Has anyone seen the research lately indicating that red and yellow are the colors that trigger appetite? Amazing, science is catching up with what marketing (Wendy's, McDonalds, Denny's etc.) has known for years!