The COVID-19 pandemic "anthropause" decreased plastic ingestion in neotropic cormorants Nannopterum brasilianus in Lima, Peru.

Background: The anthropause during the recent COVID-19 pandemic provided a unique opportunity to examine the impact of human activity on seabirds. Lockdowns in Peru prevented people from visiting coastal areas, thereby reducing garbage disposal on beaches and the movement of microplastics into the ocean. This cessation of activities likely led to a temporary decrease in plastic pollution in coastal regions. We aimed to investigate this phenomenon in inshore-feeding neotropic cormorants (Nannopterum brasilianus) along the Circuito de Playas Costa Verde (CPCV), situated on the coastal strip of Lima, Peru (∼ 11 million people). Methods: We collected and analyzed fresh pellets along the CPCV before (over 11 months) and during the pandemic lockdowns (over 8 months). Results: Our findings revealed a significant reduction in the occurrence of plastic in pellets during the pandemic period (% Oc = 2.47, n = 647 pellets) compared to pre-pandemic conditions (% Oc = 7.13, n = 800 pellets). The most common plastic debris item found in the pellets was threadlike microplastic. Additionally, our study highlights the direct correlation between human presence on beaches and the quantity of microplastics (mainly threadlike) found in cormorant pellets. We suggest that the reintroduction of these materials into the sea, previously accumulated on the coast, is likely facilitated by the movement and activity of beachgoers toward the ocean.

Prevalence of plastic debris in nests of two cormorant species in Peru.

The guanay cormorant (Leucocarbo bougainvilliorum) and red-legged cormorant (Poikilocarbo gaimardi) are known for their prolific nest-building behavior, utilizing a diverse array of materials, including anthropogenic debris, thereby serving as valuable indicators of ocean plastic pollution. To elucidate inter-specific variations in nest plastic occurrence between these two cormorant species, we conducted a comprehensive examination of nests at 12 colonies along the Peruvian coast in 2018-2019. Our findings revealed a significantly higher occurrence of plastic in red-legged cormorant nests (mean 50 ± 27 %, N = 100 nests in 7 colonies) compared to guanay cormorant nests (mean 10 ± 20 %, 3497 nests in 8 colonies). Furthermore, the prevalence of plastic waste varied across colonies within both species. Off-white/clear plastic bags were the predominant color and type of debris found in both cormorant nests. This study is a baseline of plastic marine pollution occurrence along the Peruvian coast.

Guanay cormorant (Leucocarbo bougainvilliorum) pellets as an indicator of marine plastic pollution along the Peruvian coast.

Plastic pollution affects many taxa worldwide, and monitoring is crucial for understanding its impacts, particularly where plastic reaches threatened species or those destined for human consumption. This study evaluates plastic ingestion in Near Threatened guanay cormorants (Leucocarbo bougainvilliorum), which catch prey that are also targeted by fisheries, through pellet analysis at ten locations in Peru. Plastic occurred in 162 (7.08 %) of 2286 pellets, consisting of mainly user plastics, including 5 % between mega or macro (>20 mm), 23 % meso (5-20 mm), 67 % micro (1-5 mm) plastics and 5 % ultrafine (1 µm-1 mm). We found significantly higher percentages occurrence of plastic for colonies close to more river mouths. Our results show that seabird pellet sampling is a useful tool for monitoring marine plastic pollution in Peru.

Nonrandom spatial distribution of Neotropic Cormorants (Phalacrocorax brasilianus) along a coastal highway in Lima, Peru.

Neotropic Cormorants (Phalacrocorax brasilianus) are common seabirds along the Peruvian coast. They frequently perch on trees, poles and port structures in urban areas, producing guano that builds up in areas of high levels of human activity. Hundreds of Neotropic Cormorants rest on lighting poles and telephone cables along a 12.7 km highway in the coastal strip of the city of Lima, Peru. We hypothesized that the distribution of the cormorants along this highway is clustered and could be associated with physical features of both the coast and the adjacent marine area. Fortnightly or monthly surveys were performed from July 2018 to March 2020 in the Circuito de Playas de la Costa Verde highway. At each survey, cormorants were counted per lighting pole and adjacent telephone cables (collectively, "pole-cable") at four count hours (0600 h, 1000 h, 1400 h and 1800 h). Our results revealed that daily bird numbers varied from 46 to 457 individuals and that only 17% of the total number of pole-cables (N = 651) was occupied once by at least one individual. The number of cormorants also varied between count hours within the same day (higher numbers at 1000 h and 1400 h). Birds were clustered into a maximum of five hotspots along the highway. According to a model selection criterion, higher numbers of cormorants on pole-cables were associated mainly to a closer distance from these structures to the shoreline and to the surf zone, suggesting that Neotropic Cormorants may select such pole-cables as optimal sites for sighting and receiving cues of prey availability. Based on the results, the use of nonlethal deterrents and the relocation of these birds to other perching structures on nearby groynes could be the most suitable management proposal for the problems caused by their feces.

Response of colonial Peruvian guano birds to flying UAVs: effects and feasibility for implementing new population monitoring methods.

BACKGROUND: Drones are reliable tools for estimating colonial seabird numbers. Although most research has focused on methods of improving the accuracy of bird counts, few studies have evaluated the impacts of these methods on bird behavior. In this study, we examined the effects of the DJI Phantom 3 drone approach (altitude, horizontal and vertical descent speeds) on changes in the intensity of behavioral response of guano birds: guanay cormorants (Phalacrocorax bougainvilli), Peruvian boobies (Sula variegata) and Peruvian pelicans (Pelecanus thagus). The breeding and non-breeding condition was also evaluated. METHODS: Eleven locations along the Peruvian coast were visited in 2016-2017. Drone flight tests considered an altitude range from 5 to 80 m from the colony level, a horizontal speed range from 0.5 to 15 m/s, and a vertical descent speed range from 0.5 to 3 m/s. The intensity of the behavioral response of birds was scored and categorized as: 0-no reacting, 1-head pointing to the drone (HP), 2-wing flapping (WF), 3-walking/running (WR) and 4-taking-off/flying (TK). Drone noise at specific altitudes was recorded with a sound meter close to the colony to discriminate visual from auditory effects of the drone. RESULTS: In 74% of all test flights (N = 507), guano birds did not react to the presence of the drone, whereas in the remaining flights, birds showed a sign of discomfort: HP (47.7%, N = 130), WF (18.5%), WR (16.9%) and TK (16.9%). For the drone approach tests, only flight altitude had a significant effect in the intensity of the behavioral response of guano birds (intensity behavioral response <2). No birds reacted at drone altitudes above 50 m from the colony. Birds, for all species either in breeding or non-breeding condition, reacted more often at altitudes of 5 and 10 m. Chick-rearing cormorants and pelicans were less sensitive than their non-breeding counterparts in the range of 5-30 m of drone altitude, but boobies reacted similarly irrespective of their condition. At 5 m above the colony, cormorants were more sensitive to the drone presence than the other two species. Horizontal and vertical flights at different speeds had negligible effects (intensity behavioral response <1). At 2 m above the ground, the noise of the cormorant colony was in average 71.34 ± 4.05 dB (N = 420). No significant differences were observed in the drone noise at different flight altitudes because the background noise of the colony was as loud as the drone. CONCLUSIONS: It is feasible to use the drone DJI Phantom 3 for surveys on the guano islands of Peru. We recommend performing drone flights at altitudes greater than 50 m from guano bird colonies and to select take-off spots far from gulls. Likewise, this study provides a first step to develop guidelines and protocols of drone use for other potential activities on the Peruvian guano islands and headlands such as surveys of other seabirds and pinnipeds, filming and surveillance.

Patterns of GPS tracks suggest nocturnal foraging by incubating Peruvian pelicans (Pelecanus thagus).

Most seabirds are diurnal foragers, but some species may also feed at night. In Peruvian pelicans (Pelecanus thagus), the evidence for nocturnal foraging is sparse and anecdotal. We used GPS-dataloggers on five incubating Peruvian pelicans from Isla Lobos de Tierra, Perú, to examine their nocturnality, foraging movements and activities patterns at sea. All instrumented pelicans undertook nocturnal trips during a 5-7 day tracking period. Eighty-seven percent of these trips (n = 13) were strictly nocturnal, whereas the remaining occurred during the day and night. Most birds departed from the island after sunset and returned a few hours after sunrise. Birds traveled south of the island for single-day trips at a maximum range of 82.8 km. Overall, 22% of the tracking period was spent at sea, whereas the remaining time was spent on the island. In the intermediate section of the trip (between inbound and outbound commutes), birds spent 77% of the trip time in floating bouts interspersed by short flying bouts, the former being on average three times longer than the latter. Taken together, the high sinuosity of the bird's tracks during floating bouts, the exclusively nocturnal trips of most individuals, and the fact that all birds returned to the island within a few hours after sunrise suggest that pelicans were actively feeding at night. The nocturnal foraging strategy of Peruvian pelicans may reduce food competition with the sympatric and strictly diurnal Guanay cormorants (Phalacrocorax bougainvillii), Peruvian boobies (Sula variegata) and Blue-footed boobies (S. nebouxii), which were present on the island in large numbers. Likewise, plankton bioluminescence might be used by pelicans as indirect cues to locate anchovies during their upward migration at night. The foraging success of pelicans at night may be enhanced by seizing prey close to the sea surface using a sit-and-wait strategy.