Data from: Parrots consume sodium-rich palms in the sodium-deprived landscape of the Western Amazon Basin

Herbivorous animals face shortages of different minerals in
different geographic areas. In the Amazon basin, sodium is often limiting,
driving herbivores to seek supplemental sources. In the lowlands of the
western Amazon basin, parrots commonly consume sodium-rich soils at clay
licks but lick use varies widely among species and to date, parrots in the
region have not been reported consuming other supplemental sodium sources.
We document 11 species of psittacines consuming sodium-rich leaves and
trunks of Attalea butyracea palms growing on sodium-rich soils in lowland
Peru. Consumed palms had more sodium and less potassium than uneaten A.
butyracea palms and other palm species in the area. Among A. butyracea palm
parts, sodium and Na:K ratios were highest in trunks (consumed by parrots
in 91% of the 721 foraging bouts recorded) and lowest in leaves (consumed
in only 14% of foraging bouts). The low potassium and high Na:K ratio
suggest that birds may be seeking not just any sodium sources, but those
low in potassium, as potassium is known to exacerbate dietary sodium
shortages. Use of the palms and species’ abundances in the study area were
not correlated. Instead, parrot species that consumed palms the most were
those that use relatively few traditional soil clay licks. This finding
suggests that parrot species in the region have fundamental differences in
preferred strategies for obtaining supplemental sodium and may help explain
documented interspecific differences in geophagy. .

植食性动物在不同地理区域会面临不同类型的矿物质缺乏问题。在亚马孙流域，钠元素往往是限制性营养因子，驱使植食性动物寻求补充性钠源。在亚马孙流域西部低地，鹦鹉通常会在黏土舔舐点（clay licks）取食富含钠的土壤，但不同物种对舔舐点的利用差异显著，且截至目前，该区域鹦鹉尚未被报道会摄取其他类型的补充性钠源。我们本次研究记录了11种鹦鹉类（psittacines）在秘鲁低地取食生长于富钠土壤上的阿塔莱棕榈（Attalea butyracea）叶片与树干的行为。被取食的该种棕榈，相较于该区域未被取食的阿塔莱棕榈以及其他棕榈物种，钠含量更高、钾含量更低。在阿塔莱棕榈的不同部位中，树干的钠含量与钠钾比最高——在记录的721次觅食事件中，91%的觅食事件以树干为取食目标，而叶片的钠含量与钠钾比最低，仅14%的觅食事件会取食叶片。较低的钾含量与较高的钠钾比表明，鸟类所寻求的并非任意钠源，而是钾含量较低的钠源：因为已知钾会加剧膳食中的钠缺乏状况。研究区域内鹦鹉对该棕榈的利用情况与其种群丰度并无相关性。相反，取食该棕榈频次较高的鹦鹉物种，恰恰是那些依赖传统黏土舔舐点较少的类群。这一发现表明，该区域的鹦鹉物种在获取补充性钠源的偏好策略上存在本质差异，或可解释此前已被记录的不同物种间食土行为（geophagy）的种间差异。