In the first part of my island biogeography post, I talked about how animals got to islands, giants, dwarves, copycats, and adaptive radiation (I suggest clicking this link if you need a refresher). Now in part 2, I will talk about one of the downsides that animals living on islands face: vulnerability to a variety of threats. Just a warning: I will be talking about touchy subjects including climate change and feral cats in this post, which I have learned from experience is a subject people do not like to talk about and often ends in a fight. Please keep it civil in the comments, otherwise I may have to delete some comments on the subject.
There are examples of how fragile island ecosystems are present in the fossil record long before humans evolved. One such is of one of the many islands bathed in the azure waters of the Tethys Seaway during the Jurassic Period that would one day become the bedrock of Europe. As I mentioned last time, animals living on islands that are normally larger on the mainland are smaller due to constraints of space and resources, and this was no different for the Lagenberg quarry in Germany. Dinosaur fossils found there are mostly of dwarf taxa found elsewhere in Portugal, Africa, and North America such as an island species of the megalosauroid Torvosaurus, diplodocoids, stegosaurs, several indeterminate theropods, and a miniature brachiosaur known as Europasaurus, which was found in a large assemblage which suggests that a herd of these tiny sauropods drowned en masse and were scavenged by crocodilians and fish as evident by tooth marks on the fossils. About 35,000 years after the sediments of the drowning incident were deposited, a series of large tracks suggesting the formation of a landbridge which led to a faunal overturn of the site. The resident Torvosaurus has been estimated to be 13 feet in length, whereas the arriving theropods were estimated to be between 23 and 26 feet long if reconstructed as a relative of Allosaurus, which had been found in North America, Portugal, and possibly East Africa. It's possible that the creators of the tracks hunted the mini dinosaurs, who stood no chance against the larger invaders, to extinction. Sound familiar?
What first made the wildlife of the Galápagos islands recognized around the world was not for Charles Darwin's observations on natural selection, but as a food source. Pirates would use the islands as a hideout from Spanish naval forces while stalking the oceans to plunder cargo ships laden with riches from the Spanish colonies in the Americas sailing to Europe. The islands didn't have much mineral use to the pirates, but instead they served as a limited but substantial source of fresh water for the pirates and more importantly as a source of food. If you guessed that pirates hunted the tortoises for food, you would be correct. Giant Tortoises were a preferred source of food for sailors, pirates, and whalers because they were docile and large enough to feed several crew members. Ship crew members would often capture as many tortoises as they need and bring them aboard to kill later; seabirds and sea lions were often slaughtered on the beaches. Intensive harvesting would take a heavy toll on tortoise numbers, whose late age of reproductive maturity and low likelihood of hatchlings surviving could not keep up with the pressure of hunting.
The animals of the Galapagos weren't the only ones to fall victim to the appetites of sailors, as one of the most famous extinct animals in written history (second only to mammoths if cave paintings count as writing) was also a soft target for hungry seafarers, I'm of course talking about the Dodo. Pop culture has painted a picture of this island inhabitant as so slow and dumb, it was destined for extinction, but the reality about this giant is much different. Comparisons of brain size to body size leads scientists to conclude that Dodos were actually fairly smart, and depended more on smell than sight to find the abundant fruit on the island, supplemented with small land vertebrates and shellfish. Dodos weren't dumb, they had lost all adaptations to avoid predators because there were none on their island home of Mauritius until humans arrived and exploited them as a source of fresh meat like with the tortoises of the Galapagos
When pirates, whalers, and sailors arrive on islands such as Mauritius or the Galápagos, they often introduce livestock such as sheep, goats, and pigs to provide an additional source of food for when they pass through the areas in addition to the native mammals, seabirds, tortoises and/or Dodo. However, introducing such herbivores to an island can have disastrous effects as they trample and browse on native plants down to the roots if not properly contained, preventing the plants from regrowing.
One of the most widespread introduced species on islands is one that was not intentionally released by humans. Rats and ants have found their way to many island groups as stowaways on ships and plants, and with no predators on the islands, they rapidly spread upon making landfall. In large swarms, Little Fire Ants (Wasmannia auropunctata) drive native insects out of forest habitat and attack ground nesting birds and reptiles which have no enemies. Rats are particularly dangerous for native birds because they prey on nests, eating the eggs and chicks as well as the adults and competing with them for food. To protect their sugarcane crops, plantation owners introduced Small Indian Mongooses (Herpestes javanicus) from India to Molokai, Maui, and Oahu and have since spread to every Island except Lanai and Kauai, hoping they would prey on the rats. This did not go as planned because the rats are mostly nocturnal while the mongooses are diurnal and instead targeted the eggs and hatchlings of native ground-nesting animals instead such as chickens, francolins, and Hawaiian Geese. Goose numbers were around 25,000 when Europeans first arrived in Hawaii in 1778, but by the 1950s, they had been reduced to 30
As if two introduced mammalian predators wasn't enough for Hawaii's endemic birds to deal with, they also have to battle mosquitos that transmit deadly diseases such as Avian Malaria. It results when a blood-borne parasite, Plasmodium relictum, is transmitted from infected birds to healthy birds by mosquitoes under suitably (warm) temperatures. Once infected, many birds die. Thus, the introduction of mosquitoes made it possible for native birds to become infected, given that a reservoir of disease was present, such as invasive birds like the Japanese White-eye and Red-billed Leiothrix. It's estimated that P. relictum has caused the extinction of a third of the 55 species of Hawaiian Honeycreepers present when Europeans arrived. The survivors retreated to higher elevation forests where cooler temperatures inhibited the growth of the parasite, but many fell victim to the disease...
If the idea of an entire island disappearing underwater sounds ridiculous, guess what: it actually happened! East Island is a low-lying islet surrounded by shallow reefs in the French Frigate Shoals, part of the Northwest Hawaiian Islands, and one of the most important nesting sites for Green Sea Turtles in Hawaii, most of which were born on the island. East Island recently made news when storm surge by Hurricane Walaka washed away most of the island, leaving a 150 foot sliver behind. While the reduction in size of East Island has not directly been linked to anthropogenic climate change, it it contributes to the strength and frequency of hurricanes like the one that overtook the island. Part of the theory that hurricanes will become more frequent and stronger is because warmer water provides more energy to feed them, which has been reinforced by computer simulations that produce more intense storms with rising ocean temperatures. To quote an article from the New York Times: “This is probably a forebear of things to come.”
Tropical storms often have massive impacts on tropical islands, and none were nearly as damaging as Hurricane Iniki in 1992 (around the same time Jurassic Park was filmed and may have inspired "Hurricane Clarissa" from The Lost World novel, Steven Spielberg even included footage of the storm making landfall in the associated scene when Dennis Nedry shuts down the parks security system and the Tyrannosaurus escapes). Iniki made landfall on the south-central portion of Kauaʻi, bringing its dangerous inner core to the entire island. Storm surges reached 6 feet high in most parts of the island, sometimes reaching 18 feet with waves as high as 35 feet causing a debris line more than 800 feet inland. Thousands of homes on Kauai were either damaged, destroyed, or lost completely. Agriculture was also heavily impacted by Iniki. Though much of the unharvested sugar cane crop was severely damaged, tender tropical plants like bananas and papayas were destroyed and fruit and nut trees were uprooted or damaged. On the island, one person died when struck by debris, while another lost her life when a portion of her house fell on her. Offshore, two Japanese nationals died when their boat capsized. The Kauai Nukupu'u was abundant until the 1800s when clearing of forests for agriculture destroyed much of its habitat and forcing them to take refuge in the Alakai plateau along with many of the other endemics. The damage caused to the island by Iniki may have led to the nukupu'u's extinction, as they were not seen after 1996.
I added this video of a Kaua'i O'o singing at the end mainly to show how great the impact of humans is on island endemics. One of the few recordings of a Kauai O'o is of the last male alive at the time singing for a mate that will unfortunately never come. "Now his voice is gone"
To end on a good note, I should mention that all hope is lost for island biodiversity, as there are many I've done lots of research on conservation groups whose work focuses on islands, and here are some of my favorites:
Lifers indicated in bold
While I was looking through my photos from Arizona, drawing on my computer, and debating if I should go for the Great Black Hawk in Maine, I noticed a photo of a hummingbird taken at the Paton Center right before the battery died that didn't fit with Broad-billed. "I think this is a Violet-crown..." I muttered to myself. It didn't have the violet in the cap, but the white throat was enough for me to identify this as a Violet-crowned Hummingbird, although southeast Arizona is short on similar Amazilias that I could confuse it with; one which is Green-fronted Hummingbird, which has a deep green crown, the two rarely overlap in range. Make that one more until I hit 500!
By this time, I had seen a nice variety of local and continent-level rarities for the year. However, the one bird that I’ve dipped on more this year (and my life, as a matter of fact) than any other is Black-headed Gull. Over the course of 6 months (January-April and October-now), I had chased any reported Black-headed Gull I could get word of and checked every flock of Bonaparte’s Gulls I came across on the off chance I would find one myself, to no avail (although one Bonie flock in Montauk yielded a Little Gull), only beat out by Sandhill Crane and Eastern Screech-Owl for the number of times I struck out this year. The first nemesis bird I ever had, and the only one comparable to the number of times I failed to find it, was the Peregrine Falcon. For years, I kept looking upwards until I finally saw one at Hawk Mountain in 2015. Next was Golden Eagle, which I thought I had until a reviewer for Wyoming told me the photos I uploaded were actually that of a Bald Eagle. Then Merlin, Long-eared Owl, Henslow’s Sparrow, Black-headed Gull, and Connecticut Warbler found their way onto the nemesis list; I had scored on the falcon, the eagle, the owl, and the sparrow in that order, but having given up on looking for the warbler after a month, the gull stood as my ultimate nemesis. Kenny Bostick and his search for a Snowy Owl in The Big Year had nothing on me and the Black-headed Gull (which ironically, I often see Snowy Owl on my first try for them). In a text chain with Ryan Zucker about my stats, he told me that I should “look for the BHGU at Jones Beach for #500,” which I agreed to, having set up a 500th species teaser icon with a generic flycatcher silhouette with a large question mark in the center, and several species that had the potential to be #500 hidden from view, one of which was the gull, the other was a Barnacle Goose. When I got to the coast guard station, there were several gulls there, but none had the red legs or dusky underwing I was looking for.
Like the Pink-footed Goose I've mentioned earlier, Barnacle Geese are a common "wrong way" migrant in North America. The majority of them winter in Europe, but breeding populations in Greenland sometimes get confused and fly south with Canada Geese. On migration and their wintering ground, Barnacles act no different from other geese; in their Arctic breeding grounds, however, they take nesting to the extreme and choose to lay their eggs on high cliffs where Arctic Foxes can't reach them. This means newly hatched young have to jump from heights that rival the nest-falling antics of Wood and Mandarin Ducks. I had planned to look for a Barnacle Goose that chose to winter in eastern Long Island for a few weeks, and I needed to break up the monotony of looking for the Black-headed Gull. I scanned flocks of Canada Geese at two separate locations before calling it a day, but by the time I realized I had been checking the wrong spots, it was too late for me to turn back...
The morning after, I went back to the coast guard station, but once again, there was no gull with little red feet to be seen. I was wondering if I would ever get Black-headed Gull…
Well, now we know how it's surviving.” - Nate Swick
You knew this was coming, with a notable lack of any easy birds in NY left, how could I resist chasing the rarest bird in North America at the time? Of course, I am talking about the Great Black Hawk in Maine. For birders, this rarity’s tale needs little explanation, but for everyone else: In late April, a Buteogallus was photographed at Sheepshead lot on South Padre Island, later identified as a Great Black Hawk by the lack of a thick subterminal band, white uppertail coverts, and its size; larger than a Common Black and smaller than a Solitary Eagle. The bird was last seen flying to the northeast, destination unknown… Later, in August, another Black Hawk was supposedly photographed in Biddeford, Maine, of all unlikely places. At first, birders considered the sighting to be a hoax, but subsequent identification of the plants in the photo as Japanese Knotweed and Red Maple confirmed it was in the Biddeford area, which, coincidentally, also is where the ABA area’s first Variegated Flycatcher was found. Many birders had toyed with the idea that it was the same Great Black Hawk seen in South Padre Island earlier in the year, and was confirmed through comparison of Alex Lamoreaux’s photos from Texas and Francis Morello’s photos from Maine (see footnotes). The hawk stayed for two days before flying out to sea, heading for a still unknown destination, then turned up in Portland towards the end of October before disappearing again. Surely it would be headed south now, which is what we thought, until it was posted to What’s This Bird? again, in a video of it eating a squirrel and flying off with it. Unlike the last three times it was seen, black feathers were noted, and there was snow on the ground. However, an urban park in Maine is not an ideal place for a tropical bird of prey, which was additionally identified as the Central American subspecies. "This bird is doomed," I thought as temperatures in Maine steadily dropped...
I anticipated the worst when I saw that snowstorms were in the forecast for Portland, but as finals were drawing to a close for me, I read an article on Audubon saying that this bird was STILL ALIVE after two snow storms! I decided that was enough incentive for me to go up to Maine to see this survivor. After a night of sweet talk, my mom finally agreed to go after finals. I had initially planned to go to Maine over the summer to get all the Atlantic alcids, Arctic Tern, Spruce Grouse, and to clean up breeding birds that I missed in migration; but that didn't work out, but if it had, this would've been my second trip to Maine this year. I don't let most rarities go until I have no other choice, except maybe the Barnacle Goose, so as a fail-safe on the off chance the hawk was gone when I got there, I planned backup stops to ensure I would get to 500: one on the way up in Rhode Island for a Black-headed Gull (I was getting tired of missing the Jones Beach bird), and two on the way back to seawatch for murres in Massachusetts and for Tufted Duck in Connecticut respectively. Straight off the ferry, we headed right to the spot where the gull has been seen. As we were arriving at the spot, I shouted "THERE!" in excitement when I saw the white stripe on the primaries characteristic of Chroicocephalus gulls, but I wanted a closer look to make sure it wasn't a Bonaparte's anyway. Upon closer inspection when the bird had landed, this one definitely had the lighter mantle and most importantly, deep red legs and bill. "This is it," I said, "This is a Black-headed Gull!" What an excellent bird for #500 this was. Satisfied with having conquered a major nemesis, we headed north for an even bigger prize.
The next morning, my mom and I went straight to Deering Oaks Park after breakfast to look for the Great Black Hawk. I checked every tree it could be roosting in, then when another birder came up to me, I learned it was seen on Grant Street, not in the park itself. I followed him to a line of other birders with their optics trained on this hardy little Great Black Hawk as he feasted on a recently killed squirrel. I capitalized on the opportunity and did something I rarely do: captured video of the bird in action. After months of following the story of this legendary vagrant, I was genuinely thrilled to finally see this bird for myself and experience it with other like-minded birders, which was a far better experience than with the self-proclaimed "Hot duck." As we walked back to the park, a Bohemian Waxwing flew over, 501 and 502 respectively, but depending on the taxonomy you follow, the Great Black Hawk could be 500 for the year instead of 501. I follow eBird's taxonomy/the Clements Checklist, which splits the Mexican Ducks I saw in Texas from Mallard, while the American Ornithological Society treats them as conspecific (I changed taxonomies after this year's lack of favorable splits). Using Clements/eBird, 500 would be Black-headed Gull, while it would be Great Black Hawk under the AOS Check-list. If you follow the International Ornithological Union's taxonomy, which splits a bunch of stuff that AOS and Clements don't such as Audubon's Warbler, Mangrove Warbler, and Scopoli's Shearwater, 500 would be Lesser Nighthawk; not as exciting of a 500 as an ABA first or your former nemesis. Irregardless of what taxonomy you use, one thing is constant: just as I had begun the year with a code 5, I was about to end it with a code 5.
On the way home, we drove through a storm that was equally intense as the one on the way up to get to a seawatch spot in Rockport, which has had some excellent alcid movement earlier in the week. Most of the birds I saw here were scoters and more Common Eiders, along with a few surprises, such as a male Harlequin Duck and a flyby Thick-billed Murre. As it was too dark to try for the Tufted Duck when we arrived in Connecticut, the murre would be my last new bird in the continental ABA Area without a literal Christmas miracle.
On Christmas Morning, I went out to Montauk in search of a Common Murre reported there, but had no success. That night, my needs alerts were silent. There were no more easy birds for me to get on Long Island. The resident pair of Great Horned Owls was calling to each other, another sign that spring was on the way. For me, it was a sign that it's time to move on and finish the big year with a bang…
To be continued…
Link to What’s This Bird? posts: https://www.facebook.com/groups/whatsthisbird/permalink/1941890982526285/
Francis’s map of the hawk’s sightings: https://drive.google.com/open?id=1pH6FQm-bacY-L0K8Mzk4ktEKPEVskA1J&usp=sharing
As many of you know, I will be traveling to the Hawaiian Islands to complete my Young Birder Odyssey big year. I thought this trip would also be a good way to revive my evolutionary biology series that I've skimmed the surface with in my posts on redpolls and feathers, now I'm going to discuss how islands affect the evolution of the animals living there, and I will primarily be using various examples from the Hawaiian Islands to help provide examples of what I discuss, including giant waterfowl, long-legged owls, and of course the native honeycreepers that rival Darwin's finches as an example of adaptive radiation from a common ancestor (sorry if you were expecting me to write a post on them). Because Hawaii unfortunately lacks the dwarf elephants, monitor lizards, tortoises, ratites, lemurs, azdharchids, tiny iguanodonts, and some of the other animals featured in Trey the Explainer's Biology on Islands video, which I have watched numerous times in preparation for this post, so I will borrow examples from Madagascar, New Zealand, Indonesia, the Galapagos, Mediterranean, West Indies, California's Channel Islands, and others to supplement the Hawaiian examples when helpful.
One sixth of all land area on earth is geographically separated from everything else. Unlike continents, islands are small and secluded. This isolation means only a few selective organisms can exist on them, if they can get there in the first place. There are three main ways animals get to islands: by flying or swimming there, by crossing natural land bridges that are now underwater, or as castaways of storms. Many birds were able to fly from the mainland to islands, often blown off course or intentionally, and establish themselves there. Seals are long-distance travelers that in many cases can also swim to islands if they need to. Another interesting case is of the Komodo Dragon (Varanus komodoensis), which is theorized to have originated in Australia and moved north to escape the receding forest habitat as deserts took over following a landbridge to New Guinea and Indonesia. However, the islands inhabited by dragons today were never connected to Australasia by the landbridge, so scientists theorize the dragons colonized them by swimming (they are surprisingly good swimmers). Inclement weather can blow flying animals off course on migration, leaving them stranded on islands as well. This is how the ancestors of the native bird species and subspecies got there, as well as those of the native arthropods and Hawaiian subspecies Hoary Bat. In short, most of the native wildlife in Hawaii got there by accident.
A land-bridge is an area of a continent that is exposed when sea levels are lower, allowing animals to travel between the future islands and the mainland. This is how life has been able to cross between the Americas and Eurasia during the many intermittent periods in history from the Cretaceous to the Pleistocene when the Bering Land bridge connecting Alaska and Russia was open due to lower sea levels. Another interesting land bridge relevant to island biogeography is one that existed in northwestern Europe called Doggerland. During the last ice age, sea levels were lower, and the British Isles were connected to the rest of Europe by a grassy plain called Doggerland that will one day rest at the bottom of the North Sea. These plains supported a variety of European megafauna including mammoths, bison, horses, lions, Megaloceros, rhinos, reindeer, and nomadic humans. Over time, as the climate warmed, these humans and animals were forced to migrate to higher elevations in Britain and the Netherlands as sea levels rose due to melting ice sheets and a tsunami off the coast of what is now Norway.
The rafting theory states that animals sometimes trapped mats of vegetation that blow out to sea during storms, and when they reach the nearest island, they are able to colonize the new land. This is how all of Madagascar's native land mammals got there as well as the ancestors of the iguanas and tortoises in the Galapagos.
Foster's rule, also known as the island rule or the island effect, is a biological rule stating that members of a species get smaller or bigger depending on the resources available in the environment. The rule was first stated by J. Bristol Foster in 1964, in which he compared 116 island species to their mainland varieties. He proposed that certain island creatures evolved into larger versions of themselves while others became smaller. He proposed the simple explanation that smaller creatures get larger when predation pressure is relaxed because of the absence of some of the predators of the mainland, and larger creatures become smaller when food resources are limited because of land area constraints.
The more famous residents of definitely the giants. In the absence of predators or competition for resources, animals living on islands have grown enormous, such as the moas and Haast's Eagles of New Zealand or the Galapagos Tortoises. Despite the presence of kiwis in New Zealand, the closest relatives of the giant moas are a clade of South American paleognaths called tinamous, which are still capable of flight. Despite their size, moas had one predator before the arrival of humans: Haast's Eagle, which had a 3 meter wingspan. Like the moas, they became extinct shortly after humans arrived. The Galapagos Tortoises are the most famous of the living giant tortoises, but another species of giant tortoise, the Aldabra Tortoise, lives on an island northwest of Madagascar with which it shares it's name. Earlier, I mentioned that Komodo Dragons evolved in Australia and moved northward, there was an even bigger monitor lizard related to the dragons to inhabit Australia known as Megalania or Varanus priscus, which became extinct due to climate change along with its preferred prey of giant kangaroos and wombats. Even Hawaii had its own giant flightless birds (a common theme on islands in the Indo-Pacific). In addition to living and extinct species of Hawaiian Goose or Nene, the Southeast islands were home to four species of flightless geese known as Moa-nalos and the Giant Hawaiian Goose (Branta rhuax).
Islands can also decrease the size of the animals living there due to limited resources and space. One of the most nocticable examples are the Channel Island Fox and Pygmy Mammoth, smaller relatives of the Gray Fox and Columbian Mammoth that live on the mainland in California. I've included other examples, such as Giant Anteater-sized ground sloths and pygmy chameleons
Convergent evolution is when two unrelated animals evolve similar appearances in response to similar environments. One example of convergence that I find most fascinating is one of two Island species imitating each other. In the absence of rodents on New Zealand, a group of ratites shrunk to fill the role of nocturnal opportunists. Kiwis traded flight for a longer bill and an enhanced sense of smell to hunt for insects and worms on the floor of the temperate rainforest, at the cost of good eyesight. What I find most interesting, possibly even more interesting, is that Hawaii has its own version of a kiwi! The Kaua'i Mole Duck (Talpanas lippa) was a flightless species of Duck related to modern-day stifftail ducks (Ruddy, Andean, Lake, Maccoa, Blue-billed, and White-headed, genus Oxyura) that like the kiwis and Kakapo, also gave up flight to hunt for smaller animals on the forest floor at night. Talpanas is unfortunately extinct, but if they were still around, finding one would have been on my list of birding priorities once I got there. Some other cases of convergent evolution in Hawaii include stilt-owls (genus Grallistrix) which evolved long legs similar to resemble those of phorusrhacids, Secretarybirds, and giant flightless Cuban owls of the genus Ornimegalonyx (unlike these owls, Grallistrix kept the ability to fly); and the Hawaiian Honeyeaters, which resemble the honeyeaters of Australasia so closely, they were considered to be part of the same family before elevated to full family status (Mohoidae)
New Zealand isn't just home to flightless birds and monstrous raptors, the islands also act as a time capsule from the age of the dinosaurs. Dense forests of tree ferns and podocarps similar to those in the Lord of the Rings series are found on both islands, and are where many episodes of Walking With Dinosaurs were also filmed. These ancient forests are home to two ancient creatures from the Mesozoic: the Giant Weta and the Tuatara, both coincidentally appearing in Spirits of the Ice Forest (episode 5). The Tuatara looks like a lizard, but is from an unrelated order called Rhyncocephala. Competition from lizards elsewhere has driven Tuataras into extinction, and now survives only on a few small islands off New Zealand’s coast.
Adaptive radiation is the diversification of a clade from one common ancestor to fill a variety of niches and exploit the abundance of food sources in their new environment. This is the reason I chose to use Hawaii as my example location in this blog post. Most people typically think of the tanagers of the Galápagos when adaptive radiation comes to mind, but I’ve chosen the Hawaiian honeycreepers not just out of personal bias, but also because their bill shapes reflect a greater divergence than that in the Galapagos and they’re more colorful (reds, greens, and yellows are more appealing than different shades of gray and brown, sorry Darwin). About 4 million years ago, the ancestors of the drepanidid finches, most likely a flock of rosefinches from the Asian mainland based on genetic analysis, was blown or flew naturally to Hawaii. Some of these finches had genes that gave them large grosbeak-like bills, others had those for long, thin bills, and others had genes for short, straight bills. Over time, finches would mate with birds that had bills which would best enable them to feed themselves and provide food for their young until they could only mate with birds of similar bill shape. This is called speciation. In Hawaii, most of the native finches can be divided into five categories: Generalists like the ‘alauahios and ‘Anianiau; nectarivores like the I’iwi, mamos, ‘apapanes, ‘Ākohekohe, and ‘Ula‘aihāwane; frugivores like the Rhodacanthis grosbeaks, koa-finches, palilas, ‘Ō‘ū, Telespiza finches, and Lanai Hookbill; gleaning insectivores like common ‘amakihis, ‘ākepas, ‘Akeke‘e, and Greater ‘Amakihi, and bark-picking insectivores like the ‘Akialoas, nukupu’us, ‘Ākiapōlā‘au, Kiwikiu, ‘Alawī, ‘Akikiki, and Po‘ouli. Some, such as the ‘akialoas, ‘amakihis, and ‘Ula‘aihāwane blur the lines between niches, exploiting multiple roles based on avalibility of food, and the Laysan and Nihoa finches have even been known to eat the eggs of seabirds when seeds and insects are scarce
Living on an island can not only alter the physical appearance of a species, but also their behavior. Island species
However, being less responsive to predators can also work against a species, and that is what I will talk about in part 2...
The YB Odyssey Facebook Page
My Flickr site
Leica Nature Observation Blog
Young Birders of the Round Table
crazed4birds (Drew Beamer)
Blue Ridge Birding (Max Nootbaar)
Whimbrel Birders Club
The Eyrie (ABA Young Birders)
The Birding Place (Aidan Place)
Lost In Nature (Jared Gorrell)
Bird Boy Canada (Ethan Denton)
Prairie Birder (Charlotte Wasylik)
Wing Tips (Tessa Rhinehart)
Soar Birding & Nature Tours (Noah Kuck)
Setophaga dominica (Oscar Wilhelmy)
Is yours not featured? Let me know