Accumulation Features of Persistent Organic Pollutants in Neotropical Migratory Songbirds
Abstract
Migratory songbirds have seen significant population declines over the last several
decades. One threat to songbird populations may be due to adverse health effects of legacy
contaminants such as organochlorine pesticides (OCPs), polychlorinated biphenyls
(PCBs), and polybrominated diphenyl ethers (PBDEs). Migratory songbirds spend the
vast majority of their annual cycle either migrating or on their wintering grounds in Latin
America; due to their annual movements they may be exposed to a wide variety of
contaminants. The major aim of this dissertation was to examine accumulation features of
persistent organic pollutants (POPs) in migratory songbirds. The specific objectives were
to 1) examine seasonal variation of contaminant accumulation in migrant and resident
songbirds, 2) determine what ecological factors, through the use of stable isotopes (δv13C,
δv15N, and δv2H), best explain contaminant levels and 3) determine the current state of the
research on POPs levels for birds in Latin America.
In general, no significant accumulation of contaminants during migration was
observed for migratory songbirds. Resident birds from Texas were significantly more
contaminated with €DE and €PBDEs compared to resident species from wintering areas
(Yucatán and Costa Rica). Residents from Costa Rica also had the lowest levels of €PCBs.
Stable isotopes revealed that there were only minor differences (≤ 2‰) in mean
liver δ13C and δ15N values between migrants and residents, indicating similar diets. Results
from linear regression models showed that δ15N was only useful in explaining €PCBs
concentrations in resident birds from Texas and in songbirds from Yucatán. A significant
relationship was found between δ13C and DDE and €PBDEs in residents from Texas; birds
from College Station were more enriched in ^13C and had elevated levels of POPs
suggesting proximity to urban environments as a source of contaminant exposure.
Significant temporal decreases in POPs levels was observed in birds from 1980 –
2018. DDE was the most frequently reported contaminant, followed by €PCBs. Levels of
contaminants were generally below those known to cause adverse health effects. The
regional distribution of the data is currently uneven with most studies coming from
Mexico, followed by Brazil, and centered on coastal regions and aquatic species.
Subject
Persistent Organic Pollutantswildlife ecotoxicology
DDE
PCBs, PBDEs, stable isotopes
Latin America
songbirds
Citation
Maldonado, Alejandra (2018). Accumulation Features of Persistent Organic Pollutants in Neotropical Migratory Songbirds. Doctoral dissertation, Texas A & M University. Available electronically from https : / /hdl .handle .net /1969 .1 /174629.