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Understanding how animals respond to large-scale environmental changes is difficult to assess because monitoring data are rarely available for more than the last few decades, if at all. Here, we demonstrate how a variety of paleoecological proxies (e.g. isotopes, geochemistry and DNA) from an Andean Condor (Vultur gryphus) guano deposit from Argentina can be used to explore breeding site fidelity and the impacts of environmental changes on avian behaviour. We found that condors used the nesting site since at least approximately 2200 years ago, with an approximately 1000-year nesting frequency slowdown from ca. 1650 to 650 BP. We provide evidence that the nesting slowdown may have been caused by a period of increased volcanic activity in the nearby Southern Volcanic Zone, which resulted in decreased availability of carrion and deterred scavenging birds. After returning to the nest site ca. 650 BP, condor diet shifted from the carrion of native species and beached marine animals to the carrion of livestock (e.g. sheep and cattle) and exotic herbivores (e.g. red deer and European hare) introduced by European settlers. Currently, Andean Condors have elevated lead concentrations in their guano compared to the past, which is associated with human persecution linked to the shift in diet.

The records of the Little Ice Age (LIA) in lacustrine sediments from southern south America (SSA) are still rare. Indeed, most of the evidence of this period in SSA comes from tree rings records. Our main goal was identifying the signal of the LIA at Laguna Polo (49° 15’ 59.4” S, 72° 53’ 38.4” W), in Santa Cruz, southern part of Patagonia. For this multiproxy reconstruction, we analyzed a 54-cm long sediment core and conducted paleoecological analysis on testate amoebae and chironomids in combination with grain-size distribution and geochemical composition (TOC, TIC, TN, biogenic silica (BiSi), δ15N, δ13C and C/N). The age model, based on radiocarbon dates and tephrochronology, indicated a basal age of ca. AD 1300. Based on the biological proxies, we divided our record into 4 zones. In zone 3 an important ecological change in both bioproxies was detected for the period AD 1420 to 1780. On the one hand, testate amoebae show an increase in abundance but a decrease in diversity. Difflugids were highly abundant and were dominated by Difflugia glans. Chironomid assemblages, on the other hand, reveal a decrease in abundance of head capsules but an increase in diversity with the appearance of Cricotopus and Dicrotendipes. The taxa of both taxonomic groups found during this period have been reported as indicators of cold environments. Grain-size analyses indicate a concurrent proportional increase in silts and clays, whereas geochemical analyses record a decrease in TN, TOC, TIC, BiSi, δ13C and the C/N ratio, but an increase of δ15N which may be indicative of a cooler and wetter period, as has been previously described during the LIA period in Patagonia., IAL-IPA 2022 Abstract Book - Lagos Memorias del Territorio