As we in the south of the world head into the colder time of the year, the north is welcoming spring. In Australia we are still firmly (and quite properly) restricted in our activities, though mostly not entirely confined to home. None of us can safely enjoy nature to the extent we're used to, but for most of us there's always something. My small contribution is to offer little windows onto various aspects of the natural world and at the moment something that might bring a smile seems called for. Birds and flowers both meet that requirement - in combination I reckon there's a lot of happy distraction.
Many parrots chew on flowers, but most of them do so destructively, taking the nectar for energy and the pollen for protein; some may incidentally transfer pollen to other flowers but they're unlikely to be offering much of a service to the plants.
Austral Parakeet Enicognathus ferrugineus feeding on Notro Embothrium coccineumat the Cuevo de Milodon* near Puerto Natales, southern Chile. This is the world's southern-most parrot, and the beautiful Notro (very like the Australian waratahs and closely related to them) is widespread in Patagonia. (*Go to 10th photo in link.) |
Mitred Parakeets Psittacara mitratus below Macchu Pichu, Peru. This seems to be a pea flower, perhaps another Erythrina; unlike the lorikeet above they are dimembering the flowers. |
Parrots aren't the only birds that take advantage of good nectar sources without transferring pollen. A group of South American tanagers bears the name flowerpiercer, which says it all! With a sharp, often curve-tipped bill, they stab the base of the flower and 'steal' the nectar without encountering the pollen.
Black-throated Flowerpiercer Diglossa brunneiventris, Chivay, northern Peruvian Andes. This one was caught in the act of stabbing the flower base. |
Glossy Flowerpiercer Diglossa lafresnayii, Yanacocha NP near Quito, Ecuador, showing its highly specialised piercing bill. |
However at some stage the lorikeets began to feed more precisely, pushing past pollen-bearing anthers to get to the nectar and in the process collecting large quantities of pollen on the face feathers and roughened tongue. Or rather, the plants began 'employing' them rather than insects, investing in copious nectar to make the parrots actively seek out the flowers; in return the plant got a larger pollinator which could take far more pollen away, and carry it much further.
Studies on captive lorikeets showed that Yellow Gum (or Blue Gum depending on where you are) Eucalyptus leucoxylon has flowers in which the pollen is ripe before the flowers can receive pollen, to avoid self-fertilisation. Moreover the filaments which hold the pollen anthers bend over into a dense dome which effectively excludes insects. A single visit by a Rainbow Lorikeet could remove over 2000 pollen grains; when they visited older flowers ready to accept pollen they delivered on average over 120 grains per female stigma. Another strategy adopted by some - perhaps most - bird-focussed flowers is to offer nectar that is both abundant and dilute, so of limited interest to insects.
Red-collared Lorikeet Trichoglossus rubritorquis in Darwin, feeding on Umbrella Tree Schefflera actinophylla, a native of northern Australia. |
Scaly-breasted Lorikeet Trichoglossus chlorolepidotus, Goondiwindi Botanic Gardens, south Queensland. Birds are not restricted to red flowers, though they do seek them out. |
Varied Lorikeet Psitteuteles versicolor on paperbark melaleuca, Kakadu National Park, Northern Territory. |
Nectar specialising is basic to lorikeets; we have just seen evidence of it in three different genera.
Moreover, quite independently a few other parrot groups have become nectar specialists and thus pollinators as well. One of these comprises only the Australian Swift Parrot Lathamus discolor which migrates from its breeding grounds in the Blue Gum forests (E. globulus for this Blue Gum) of Tasmania to the box woodlands of south-eastern Australia.
A study showed that the Blue Gums depend heavily on Swift Parrots for pollination. Just one visit to a flower by a Swift Parrot leads on average to more than 75% of the seed set possible for that flower. Single visits by native insect pollinators led to no seed set, and by introduced bees no more than 7%.
Other parrots which are regarded as nectar specialists are the little hanging parrots Loriculus spp. of southern Asia, and the Neotropical genus Brotogeris.
Plain Parakeet B. tirica in the Atlantic forests near Sao Paulo, Brazil. |
Among other birds, three families are regarded as the key nectar specialisers; the Australian honeyeaters, the Neotropical hummingbirds and the African and Asian (and Australian, just) sunbirds. Unsurprisingly all have evolved relatively long slender decurved bills for probing tubular flowers - such flowers exclude most insect pollinators (though not some moths with extravagantly long proboscises). Pollen is carried mostly on forehead feathers - see the dusting on these two birds.
New Holland Honeyeater Phylidonyris novaehollandiae with Calothamnus sp., Cape le Grande NP, Western Australia. This is a common and widespread species in heathlands of southern Australia. |
Nectar is almost pure sugar, so such specialists must also find another source of protein; pollen provides some, but most prey on insects to supplement their diet. Perhaps also unsurprisingly, but interestingly, there are examples in all three groups where some species have secondarily re-evolved shorter beaks to focus more heavily on insects again.
Allow me to introduce some members of these groups, each of which I am very fond of, though of course I know the honeyeaters best. Like the lorikeets, honeyeaters take up the nectar by capillary action with a rapidly moving tongue.
Banded Honeyeater Cissomela pectoralis; both this and the next bird were feeding in flowering eucalypts in Nitmiluk (formerly Katherine Gorge) NP, Northern Territory. |
Bar-breasted Honeyeater Ramsayornis fasciatus. |
The Umbrella Tree flowers that attracted the Red-collared Lorikeet above, also brought in a range of honeyeaters - we watched it all while eating lunch on the verandah of the excellent Darwin Museum, looking out to the Timor Sea. (Though to be honest I was mostly looking upwards.)
Brown Honeyeater Lichmera indistincta, a widespread small honeyeater across most of Australia except the south-east. |
Another group of large honeyeaters comprises the wattlebirds - named for the red fleshy wattles on the face of the first species encountered, the Red Wattlebird Anthochaera carunculata (some subsequent species inconveniently lacked this feature).
Red Wattlebird on grevillea, Australian National Botanic Gardens. They don't normally feed on the ground, but will adapt as required. |
Little Wattlebird Anthochaera chrysoptera on Banksia marginata, Lower Glenelg NP, Victoria. The non-wattled wattlebird is common in near-coastal south-eastern Australia. |
Western Wattlebird A. lunulata on Banksia speciosa, Esperance, Western Australia. This one was long lumped with the previous one. |
Dusky Honeyeater Myzomela obscura (or Dusky Myzomela, though this use of the genus name is pretty much unknown in Australia) on a grevillea cultivar in a Darwin garden. |
Grey-headed Honeyeater on Grevillea wickhamii, Watarrka NP, central Australia. |
Scarlet Honeyeater Myzomela sanguinolenta on bottlebrush, Callistemon sp., Cape Hillsborough NP, Queensland. A delightful little bird which deserves a better photo than this. |
Yellow-faced Honeyeater Caligavis chrysops on another bottlebrush, this one in our Canberra back yard. |
And for the record here's a member of one group of honeyeaters - the miners, though they're not the only ones - with short stout beaks to reflect a primarily insect diet.
Bell Miner Manorina melanophrys, Melbourne. |
By now you're probably honeyeatered out, so time for some sunbirds; I find these little gems very hard to photograph - they never seem to stay still - so there might be a couple of pics here that I'd not normally impose on you, mostly for the sake of featuring at least one Asian one.
Beautiful Sunbird Cinnyris pulchella, Serengeti NP, Tanzania. An especially tiny sunbird, and spectacular. |
Immature male Scarlet-chested Sunbird Chalcomitra senegalensis, Serengeti NP, Tanzania. The mature male is black with a green forehead. |
Temminck's Sunbird Aethopyga temminckii, Mount Kinabalu, Sabah, Malaysian Borneo. |
And there is at least one equivalent to the short-billed insectivorous honeyeaters among the sunbirds too.
Ruby-cheeked Sunbird Chalcoparia singalensis, Ai Batang NP, Sarawak, Malaysian Borneo. |
Which brings us to our final major nectar-slurping group of birds, the hummingbirds, a huge family mostly from tropical South and Central America. They are stunners, so without further ado here are a few with, of course, flowers. If there are too many you can of course just skip through, but I do hope you've got enough time not to do that! Their hovering abilities are of course legendary.
Eastern Mountaineer Oreonympha nobilis at wild tobacco flowers, Nicotiana sp., Huaycarpay, southern Peruvian Andes. It is found only in a couple of valleys near Cusco. |
Blue-mantled Thornbill Chalcostigma stanleyi, El Cajas NP, southern Ecuador, at over 4000 metres above sea level. |
Blue-tailed Emerald Chlorostilbon mellisugus in the rain at Aguas Verdes private reserve, northern Peru. (More on this wonderful place here.) As you will see again below, lodges and gardens often plant these verbenas to attract hummers. |
Sapphire-vented Puffleg Eriocnemis luciani at Passiflora flowers, El Cajas NP (see above). |
Green Violetear Colibri thalassinus on wild tobacco, Sacred Valley near Cusco, southern Peru. (Its taxonomy is a bit fluid at the moment, but this will suffice our needs.) |
Oasis Hummingbird female Rhodopis vesper Azapa, northern Chile, a hummer of the desert coastline. |
Rufous-crested Coquette female Lophornis delattrei, Aguas Verdes (see above). |
Wire-crested Thorntail, male above, and female below, Aguas Verdes again. This is one of my favourite hummingbirds. |
And my final hummingbird is included (without a flower) because it is atypically 'naughty' in not probing the flower as intended, but takes a short cut to the nectar by punching a hole through the flower's base - like the flowerpiercers above.
Geoffroys's Wedge-billed Hummingbird Schistes geoffroyi, Mindo Valley, northern Ecuador. Note the short sharp bill. |
And finally (no, really!) just a couple of more minor examples of other families which partake of nectar - one does so pretty much exclusively but only contains two species, the other has many species but nectar is only taken as a part of some of their diets.
Silvereyes Zosterops lateralis (here on a grevillea in the Australian National Botanic Gardens) certainly pollinate flowers, but not as a major part of their life. |
Cape Sugarbird Promerops cafer on a heathy plateau north of Cape Town. One of only two species in its family, it relies heavily on protea flowers. |
OK, I really hope you're not fed up with birds and flowers after this post, which became something of an odyssey! Hopefully I was able to entertain and perhaps inform you a little, both of which should be of some help in these strange, challenging times.
NEXT POSTING THURSDAY 30 APRIL.
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Very interesting and informative as always Ian. I am aways surprised when the Eastern Spinebills visit non native plants in my garden. Yesterday they were enjoying the nasturtiums planted in our veggie garden to aid pollination. Kathy C
ReplyDeleteThanks for your kind words Kathy. Too long since we saw your garden! I think specialists like spinebills are responding to flower shape and colour and (after a quick online check) I reckon that nasturtium would suit them fine, like Fuchsias. I see that, like Fuchsias, they're from the Neotropics, so doubtless evolved with hummingbirds; what suits a hummer is generally going to suit a spinebill. Hope you see this!
ReplyDeleteYes Ian they also hover around the fuschias and pineapple sage just like a hummingbird. Even though the garden is 95% Aussie natives, it's nice to see the exotics also serving a useful purpose. Our garden looks the best it has for years. One day we will be allowed (non-Avian) visitors again.
ReplyDeleteI bet the fuchsias and p sage have genetic memories that are thrilled by it! (Perhaps.) Can we put our names on the waiting list for when you re-open? Thanks!
ReplyDelete