This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: When I first arrived in Peru's Allpahuayo-Mishana National Reserve in 2005, a local youth surprised me with an offer to sell me a live owl, despite the fact that we were in a protected area where commercial hunting was prohibited. We set the owl free together, but this turned out to be an early lesson about the vulnerability of tropical protected areas to exploitation, even when laws and policies had been put in place to protect them.
At that time, Allpahuayo-Mishana was a newly designated protected area with no paid staff except for its director, who was stationed in the nearby city of Iquitos. Almost a third of the world's bird species depend on tropical forests for survival and, in turn, play critical roles as pollinators and seed dispersers in maintaining forest structure and function. Western Amazonia harbors the highest bird species richness in the world, and Peru's Allpahuayo-Mishana National Reserve protects rare white-sand forests and nearly 600 bird species on 576 km2 (222 square miles) of land on the north bank of the Amazon River.
Unfortunately, Peru is subject to one of the world's highest rates of deforestation, driven largely by illegal logging, which destroys forests, harms people and wildlife, and is associated with steep declines in bird populations. Illegal logging is a major threat to tropical protected areas around the world. The consequences of illegal logging for birds and forests in Allpahuayo-Mishana are the subject of an article my colleagues and I published in the journal Land.
We sampled birds with mist nets, capturing and releasing birds in unlogged forests as well as forests previously logged one, five and nine years ago. We compared understory bird communities in forests with different logging histories and correlations with habitat structure variables. We also took advantage of a rare opportunity to compare bird-sampling data collected at the same forest sites in 2005 and 2023 to investigate changes in understory bird communities over this 18-year period.
Our results show that illegal logging has had a significant influence on forest structure in Allpahuayo-Mishana, with consequences for birds that persist for decades after logging events. Average bird species richness in unlogged forests was approximately 52 species, whereas one year after logging, bird species richness had declined by more than 50% (approximately 25 species). However, by approximately five years after logging, bird species richness had increased to an estimated approximately 102 species, nearly twice that in unlogged forest.
Approximately nine years after logging, bird species richness then declined to approximately 34 species, or approximately one-third that of unlogged forest. As part of our investigation, we classified understory birds into guilds based on their main foraging strategies. Ant followers accompany army ant swarms to forage on arthropods as they flee to escape becoming prey to the ants; other insectivores also hunt arthropods using strategies such as flycatching and gleaning from leaves and bark.
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