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Ancestor: Palm Island Sparrow

Size: 30cm tall

Dietary Needs: Scavenged meat and live prey. Will eat: Shelled molluscs, small crustaceans, worms, small fish, small squid, eggs of sea life, small lizards, unguarded eggs and chicks of other birds. Can tolerate meat that is significantly decayed with a more robust microbiome and stronger stomach acid. They can dissolve thin fish bones that otherwise might be a hazard to their digestive tract.

Shell thickness for calcium carbonate shell-forming animals is nerfed due to  atmospheric carbon dioxide decreasing the pH of the ocean surface. In coastal areas this food source can be accessed by the birds by breaking them against rocks or other unopened cockles. The cockles in these areas are relying more on submersion in the sediment for their survival, but Green-footed Probing Marepa are able to identify their siphon holes by sight, and then wedge their beak between the shell halves with a stabbing motion into the mud or sand where the cockle is. From there they work on breaking the shell against hard surfaces or try to kill the cockle inside with it's beak to make it open. Although difficult to access their contents, the benefit of foraging for cockles is that the cockles are plentiful, found in predictable places, don't flee and are fatty.

Life Cycle: Males are the only ones with green (or turquoise) feet and legs. Female's legs can sometimes have a faintly greenish tint, but are more often yellow or pink. Male colouration is also determined by sexual selection - females are attracted to the brighter colours, bolder markings and greater contrast, and thus such males are more likely to have offspring.

Breeding occurs seasonally during the calmer months, when  the season has already warmed significantly and spring storms have reduced. As well as showing healthy colours, males also must be good nest site selectors and have started a good foundation on a nest. He must also have been able to guard the site from rivals, as they are very competitive. Ideal nesting sites are on heights of grassy dunes amongst large, mature tufts of grass, or sometimes on rocky coastal cliff communities where they excavate small loose stones from cracks to reveal a space that is comparatively sheltered and dry from the outside, which they will then line with dry grass bedding. Nesting habits depend on local environment as different locations will have different opportunities.

Males call and display from a different location from where he built his nest. This is to avoid attracting predators to the nest. Once a female is tailing him he leads her back to his nest. From here, she might decide to stay and further court with the male before deciding to mate. Or, she might decide the nest doesn't impress her and leave.

Once a male and female have mated there is a high chance they will not separate before having chicks. Once they have raised chicks, they have bonded for life. Males are far more involved in the chick's survival than males of their sparrow ancestors.

Nests are vulnerable to sea weather, and most pairs can raise between 1 and 2 broods a year. Chick rearing extends beyond the nest, as the chicks need to learn from the parents how to find food and how to tackle some of the more difficult food they will encounter. They usually have only around 3 eggs, which can all survive on a good year but on difficult years they will pour all of their efforts into the fittest one.

Other: Their feet have longer toes and the skin around their toes spreads out under pressure, and extra skin to increase the broadness of their toes. This spreads their weight so their feet don't stick in the sand or mud, including quicksand. The birds are too lightweight for quicksand or mud to be a danger of becoming truly stuck, but the mud can still grip to thin toes because they still sink slightly. Due to creating a filled void in the mud with no air, the energy cost of movement increases as one must break the air seal to take the next step. The spreading of the foot lowers this cost as the toes don't sink in for the mud to create a strong seal. Less energy is lost from pushing the foot against the mud also, and more energy is transferred into movement of the bird. The back toe helps control the arc of the foot to prevent the base of the foot forming a seal against the mud (though sometimes it's unavoidable). The toes aren't completely webbed because they also often run through the waves rolling across the beach. If webbed, each step would be more easily misdirected by the current as the waster cannot flow between the toes, only push against the webbing. So this is the reason why their toes never evolved to be fully webbed. Another reason is that they aren't usually paddlers.

However even though they aren't paddlers it's no big deal if they end up in deeper water, such as when competing over some food they have found in the deeper water by scanning from above, or even just from ending up in the water by accident. They continuously shed hydrophobic dander (producing visible puffs of dust if lightly patted) and are buoyant, so not only do they rise to the surface immediately they can also immediately get airborne.

"Dander slick" is a phenomenon that occurs on calm waters (such as a small lake during calm weather, or a sheltered cove on the coast) where there is a high incidence of these birds. It's an extremely thin but visible film of dander powder that accumulates on the water's surface. The way the slick repels the water beneath makes the water look like it has a skin. Eventually this dander breaks down and loses it's hydrophobic quality, forming small wet clumps that add to the detritus snow that some detrivores feed on.