The curicaca pushes its long, curved bill into waterlogged ground to look for food. When the tip sinks into mud or soft earth, sensory endings help it detect hidden prey, so the bird can find a target by touch during probing, without relying on sight to confirm every movement.
That method turns marshes, wet fields and the edges of flooded areas into feeding grounds. The curicaca, known in English as the buff-necked ibis, walks slowly, pushes its bill into the ground at different spots and pulls small animals out of the soil. At dawn, flocks often take off with a characteristic call, moving between feeding areas and resting places.
The bill tip works as a sensor in the mud
The bill of the curicaca is long and curves downward, a shape that makes it easier to enter cracks, loose pockets of soil and shallow layers of mud. The very end of the bill does more than grab food. It also holds sensory endings that can register contact with the ground and the mechanical signals made by something moving beneath the surface.
While searching, the bird lowers its head and drives the tip of its bill into the ground in short movements. The pressure against the earth gives information about how firm the material is, while an unexpected movement can signal that prey is present. The curicaca does not need to see the animal directly to start a capture. Touch guides the opening and closing of the bill, especially when cloudy water, mud or low vegetation block a clear view of what lies below.
A curved shape combines reach and precision
The curve of the bill widens the bird’s ability to explore the ground without turning over large areas. Instead of lifting a broad layer of mud, the curicaca makes pinpoint probes and checks several nearby spots. This pattern saves energy and lets the bird follow the uneven distribution of prey, which may be concentrated in places with more moisture or more organic matter.
The bill is also a capture tool once the touch signal has been felt. The bird moves its head, repositions the tip and closes its mandibles around the animal it has found. Accuracy depends on the combination of sensitivity and muscle coordination. The length of the bill keeps the eyes away from the point of contact, while the curvature helps hold organisms that try to escape deeper into the soil or between small plant remains.
Touch matters most when the prey is hidden
The curicaca uses this behavior mainly where food is not exposed on the surface. Soft soil, marsh and wet fields give small animals places to hide under leaves, roots, clods of earth and sediment. In such places, searching with the eyes alone would not be enough, because prey may stay motionless, may match the color of the mud or may be partly covered by shallow water.
Tactile probing lets the bird explore its surroundings even when visibility is poor. It does not have to wait for food to move above the ground before it reacts. It tests the substrate, notices differences in contact and decides whether it is worth persisting at a given spot. The strategy can also be alternated with the capture of visible items, depending on the depth of the water, the consistency of the mud and the presence of vegetation that makes walking harder.
Using touch offers an advantage because it opens up a part of the food supply that other birds cannot easily reach. Buried or concealed prey stay available even when no insects are exposed on leaves and stems. The curicaca can take advantage of changes in soil moisture and search in places that have just become waterlogged, where the surface is easier to penetrate.
This flexibility helps the species occupy open landscapes with different water conditions. Wet fields, flooded pastures, lake margins and marshes are not a uniform environment. The texture of the soil can change within a few yards (a few meters), and so can the amount of organic matter and the concentration of small animals. A sensitive bill lets the bird test these variations without abandoning an area entirely every time prey stops being visible.
The curicaca shares its habitat with other species
When it forages in the ground, the curicaca takes part in communities made up of birds, insects, small invertebrates and organisms that live between water and land. Removing prey changes specific points of the substrate, but the bird does not transform the whole marsh. Its foraging happens in patches and combines probing with movement across the surface, keeping the search tied to places where the soil offers the right resistance.
The behavior also shows how species that use the same wet field can exploit different resources. Some birds catch animals in the water, others pick up exposed items or search the vegetation. The curicaca concentrates part of its search on contact between the bill and the ground, which lowers the overlap with techniques based on visual pursuit in the water column. Coexistence depends on environmental conditions and on the variety of microhabitats available in each area.
Flying in flocks links feeding areas
The curicaca is known for a strong, characteristic call, especially noticeable when groups fly at dawn. Collective movement can connect resting areas with the wet fields and marshes used for feeding. In the air, the birds stay in contact through calls, while on the ground each individual does its own probing and catching, adjusting its path as it finds favorable spots.
This routine shows the relationship between behavior and landscape. The curicaca depends on open areas where it can walk, on soil soft enough for the bill to enter and on places where prey stays within reach. When those conditions appear in different stretches of land, flight allows the bird to explore a network of nearby environments. The bird does not simply occupy the marsh. It also carries its foraging activity between wet fields, margins and other open areas of the biome.
Watching a curicaca in the mud may look like a simple scene, but the tip of the bill reveals a precise way of perceiving the surroundings. While sight identifies the space around the bird, touch reports what stays hidden under the surface. This division of roles is a reminder that life in wet areas does not depend only on what is in plain view. Many ecological relationships unfold in the gap between water, soil and organic matter, where a bird can find food with a touch before it ever sees it.
Reporting: Natália Santos / Amazonia Mag
Editor · Amazonia Mag
Anne Silva is the editor of Amazonia Mag, the English-language edition of Revista Amazônia. She curates, translates and adapts the outlet's science and environment coverage for an international audience, reporting on Amazon wildlife, flora, rivers, climate and research. Every story she edits is grounded in peer-reviewed studies, official data and on-the-ground reporting from the Revista Amazônia newsroom in Belém, Pará, Brazil. More by Anne Silva →