Seabird temporal composition, abundance and habitat use in “Punta La Metalera” (Arequipa), Southern Peru

Study Extent

The study was conducted in Punta La Metalera in the Islay district of the city of Arequipa, 10 km northeast of Mollendo (-72.111527 °S, -17.015428 °W). Punta La Metalera is a cape that has varied landforms: cliffs, shoreline, rocky outcrops with steep slopes and guano-covered surface, and algae vegetation. Its surrounding areas are islets. Moreover, it harbors the IPA (Artesanal Fishing Infrastructure) port. Nearby there are industries such as TISUR (South International Terminal), Diamante, fisheries, and populated areas. A short distance away, at 1.5 km, is the second largest industrial harbor of Peru, Matarani. Punta La Metalera has an area of about 8.21 ha and an average elevation of 21 m.a.s.l.; its topography is rocky with no vegetation. There is a rainy season (June-November) and a dry season (December-May). The rainy season is characterized by fog and sporadic rainfall. The mean annual temperature ranges from 15 (June-September) to 29 ºC (November-April). The annual relative humidity ranges from 70 % (January) to 84.23 % (July). The wind direction is predominantly south (S) to southeast (SE) with an average speed of 11 km/h (SENAMHI, 2019). The tidal range varies between 1.5 and to 3 m but is usually about 1 metre. Waves are moderate to high intensity. The sea surface temperature (SST) ranges from 17 to 23 °C. Before collecting data we surveyed the coast line to determine the characteristics. To minimize recounts we divided the study area into four zones that included a small islet. The four zones included the areas with the highest concentration of birds.

Sampling

We conducted 24 counts from October 2019 to March 2020 using the point count method (Bibby et al. 1992), covering around 700 m of coastline. Counting points were set for the four zones, selected based on accessibility (most of the cape coastline was difficult to access). Six trips were made (one per month). On each trip we conducted three censuses: one between 5:30 a.m. and 9:30 a.m., a second between 12 p.m. and 2.30 p.m., and a third between 3:30 p.m. and 6:00 p.m.). We spent 20 minutes at each point (Bibby et al., 1992), making a total effort of 1,680 minutes (28 hours). We only counted birds that were perched on land or at sea, not those in flight. We did not exclude only coastal birds as our aim was also to look at behavior and habitat use. However, all birds sighted (all species passing through any area) were recorded for richness. At each point, the species present were identified and quantified using Bushnell, Tasco, Nikon, and Galileo binoculars (10x50, 12x45, and 90x80), Fujifilm camera (eight megapixels), field cards, and notes. Before starting the census we waited for five minutes for the birds to adapt to our presence as our arrival caused a slight displacement of some of them, especially those on the edges. The birds we considered as coastal seabirds were species of the orders Anseriformes, Ciconiiformes, Charadriiformes, Pelecaniformes Suliformes, Podicipediformes, Falconiformes, Passeriformes (Acosta et al., 2013), Sphenisciformes, and Cathartiformes. To identify the species, we used the guides of Jaramillo (2003), Tabini and Paz-Soldán (2007) and Schulenberg et al. (2010). The taxonomic nomenclature was taken from the SACC (Remsen et al., 2020), and the category of species risk was assigned using the IUCN Red List of Threatened Species.

Quality Control

Regarding the use of the territory and behavior, we considered eight categories according to the type of activity developed by the birds during the evaluations). Additionally, we recorded the interference of anthropic activity considering boats, tourism, guano collection and any other related activity that could be considered to disturb the birds in the evaluation area.

Method steps

1. We analyzed the temporal fluctuation by comparing months and comparing the mean values for each month of the abundance variation using ANOVA (one way, p < 0.05.). Data normality was previously evaluated using the Shapiro test (Peña-Villalobos et al., 2012) and normalized using the bestNormalize (Peterson, 2020) package in RStudio (RStudio Team, 2020). The species occurrence frequency (SOF) was analyzed considering six categories (Nores, 1996 cited by Brandolin et al, 2007), which are: i) very common (0.8–1), ii) common (0.6–0.8), iii) frequent (0.4–0.6), iv)scarce (0.2–0.4), v) occasional (0.1–0.2), and vi) accidental (< 0.1). These values were obtained for each species as the number of months in which the species was present, divided by the total number of sampled months. For the species relative abundance (SRA), we considered five categories: i) abundant (90–100 %), ii) common (65–89 %), iii) moderately common (31–64 %), iv)uncommon (10–30 %), and v) rare (1–9 %). These percentages were obtained for each species as the number of individuals of a species divided by the total number of individuals considering all species and multiplied by 100 (Güitrón–López et al., 2018). The dissimilarity of species abundance between months was calculated using the index of similarity (Bray-Curtis), 1 - (2c/S1 + S2), where S1 and S2 are the number of species in sample months 1 and 2, respectively, and c is the number of species present in both sample months. This dissimilarity was represented with dendrograms using the UPGMA method with PAST v.2.17 (Kusch et al. 2008 cited by Peña-Villalobos et al., 2012) to establish a similarity relationship between assessment months on species/abundance fluctuations. And finally, habitat use (land-use) was analyzed comparing the birds' behavior s per month, for which we summed up each behavior record.

1. Laridae
   rank: family
2. Sulidae
   rank: family
3. Phalacrocoracidae
   rank: family
4. Cathartidae
   rank: family
5. Pelecanidae
   rank: family
6. Haematopodidae
   rank: family
7. Furnariidae
   rank: family
8. Spheniscidae
   rank: family

The study was conducted in Punta La Metalera in the Islay district of the city of Arequipa, 10 km northeast of Mollendo (-72.111527 °S, -17.015428 °W). Punta La Metalera is a cape that has varied landforms: cliffs, shoreline, rocky outcrops with steep slopes and guano-covered surface, and algae vegetation. Its surrounding areas are islets.