BIRDING IN GARIBALDI PASS - WILDLIFE IN USHUAIA: REPRODUCTIVE SUCCESS OF WHITE-BELLIED SEEDSNIPE.

Birding in Garibaldi Pass

The 2019–2020 season (October to April) was exceptionally interesting due to a new reproductive record of a White‑bellied Seedsnipe pair in the areas we regularly visit for observation. After three consecutive seasons without evidence of chicks or juveniles, this year finally provided clear signs of successful breeding.

Among all the field experiences carried out during this period, Birding in Garibaldi Pass stood out as the most remarkable tour. This high‑Andean route, located in the heart of Tierra del Fuego’s alpine environment, offered ideal conditions to observe the reproductive success of the White‑bellied Seedsnipe (Attagis malouinus)—something we had not documented in recent years.

A Breakthrough After Three Seasons Without Juveniles

During the previous three seasons, although adults were consistently recorded, no chicks or juveniles were observed. Even during the April–May migration period, when the species moves north toward steppe environments with similar alpine characteristics, juveniles were absent.

This year, however, weather conditions were significantly more favorable for reproduction compared to the last three seasons.

Snowfall Patterns and Climate Conditions

The year 2019 was particularly unusual in terms of snowfall. Despite late snowfalls in September and October—and large accumulations that left very few feeding patches available—the species managed to reproduce successfully.

In early November, snow still covered most of the alpine slopes. One of our passengers, Barry McKenzie, captured a photo showing a member of the pair standing in one of the few snow‑free patches available. These images illustrate the challenging conditions the birds faced at the beginning of the season.

Interestingly, although snowfall was heavy early on, conditions improved dramatically in mid‑November and December. Temperatures were higher than normal between 600 and 900 meters of elevation, creating a window of favorable conditions that likely enabled successful breeding.

In contrast, during the previous three seasons, late snowfalls were less intense, but persistent low temperatures above 400 meters may have negatively affected reproductive attempts. Snowfall continued into November and even early December in those years, limiting feeding opportunities and possibly preventing successful nesting.

Predation Risk and Environmental Stability

Another factor supporting the theory that climate conditions influenced reproductive success was the presence of a pair of Peregrine Falcons. Although they do not use this area for breeding every year, their presence did not pose a reproductive threat this season. In previous years, we recorded evidence of predation—such as scattered plumage from a dead White‑bellied Seedsnipe—suggesting that predation pressure may have been higher.

This year, however, no predation events were observed.

Documenting the Chicks

We were able to document chicks with photographs on different dates in January. These images clearly show size variation over time. Thanks to a second photo taken by John Holmes, a birdwatcher from the United Kingdom, we could compare chick growth over a one‑month period.

In both observations, the behavior of the adults was consistent with what we have seen in previous years: the pair tends to separate, with the presumed male (based on coloration) distancing himself from the female and the chicks.

In early stages, it is common to observe up to five chicks, and most typically survive to reach juvenile age with the ability to migrate.

A Season to Remember

These data are extremely valuable, and we are especially grateful to our passengers—Barry McKenzie and John Holmes—for their excellent photographs and for trusting us during their Birding in Garibaldi Pass experience.

This season not only provided the first reproductive record in years, but also reinforced the importance of Garibaldi Pass as one of the best places in Tierra del Fuego to study the ecology and breeding behavior of the White‑bellied Seedsnipe.

Birding in Garibaldi Pass: One of the Best Places to Observe the Reproductive Success of the White‑bellied Seedsnipe