Variation in population size, nest distribution, colony extent, and timing of movements at the largest known parrot colony

Psittaciformes are among the most threatened birds, and population size
and trend estimates are needed to aid conservation. The burrowing parrot
(Cyanoliseus patagonus) is undergoing substantial changes in its
population size, due to habitat degradation, trapping for the pet trade,
and persecution as a crop pest. The species formerly had several large
colonies, but these were severely reduced during a program of agriculture
pest control. Currently, only one large colony remains, together with a
decreasing number of smaller colonies spread throughout the Monte and
adjacent ecoregions. The colony at El Cóndor, north-eastern Patagonia,
Argentina, is of particular importance, concentrating 71% of the global
breeding population of burrowing parrots. We aimed to determine changes in
1) breeding population size, 2) the extent of the colony, 3) the
distribution of nests along the colony, and 4) the timing of movements
from the nest to the foraging locations during the breeding season, over
our long-term study (1998-2019). We found that the number of active nests
declined from 37531 in 2001 to 21883 in 2005, and recovered in the
following years, reaching 40671 nests in 2019. The decline observed in
2005 could be related to droughts and associated food shortage during the
La Niña phase of El Niño Southern Oscillation. The colony expanded
westwards, from 9 km length in 2001, to 18.1 km in 2019. During the same
period, the part of the colony with the highest number of active nests
shifted 5 km westwards from El Cóndor village. Both changes could be the
consequence of human disturbance. As any serious threat affecting this
colony could have severe consequences for the survival of the species,
regular monitoring is needed, together with legal protection of the
burrowing parrot colony at El Cóndor and the Monte ecosystem around it.

鹦形目（Psittaciformes）是受威胁程度最高的鸟类类群之一，亟需开展种群数量与趋势评估以助力保护工作。掘穴鹦鹉（burrowing parrot，Cyanoliseus patagonus）的种群规模正发生显著变化，诱因包括栖息地退化、宠物贸易诱捕，以及作为作物害鸟遭到灭杀。该物种曾拥有多个大型繁殖群，但在农业害鸟防控项目中遭到严重削减。目前仅存一处大型繁殖群，以及散落在蒙特（Monte）生态区及其邻近区域的、数量持续缩减的小型繁殖群。位于阿根廷巴塔哥尼亚东北部的埃尔孔多尔（El Cóndor）繁殖群尤为关键，其繁育个体占全球掘穴鹦鹉繁殖种群的71%。本项长期研究（1998-2019年）旨在探明四个维度的变化：1）繁殖种群规模；2）繁殖群的分布范围；3）繁殖群内巢位的空间分布格局；4）繁殖季内亲鸟从巢区前往觅食地的活动时序。研究发现，活跃巢位数量从2001年的37531个降至2005年的21883个，随后逐年恢复，至2019年达到40671个。2005年的种群下滑或与厄尔尼诺-南方涛动（El Niño Southern Oscillation）拉尼娜阶段的干旱及伴随的食物短缺相关。该繁殖群向西扩张，2001年时其分布长度为9千米，2019年增至18.1千米。同期，活跃巢位最密集的区域较埃尔孔多尔村向西偏移了5千米。上述两项变化或均由人类活动干扰所致。鉴于任何威胁该繁殖群的严重因素都可能对该物种的存续造成灾难性后果，亟需开展常态化监测，并为埃尔孔多尔的掘穴鹦鹉繁殖群及其周边的蒙特生态系统提供法律保护。