Written by Meredith Honig and Bryn Carter
The austral spring field season at Punta Tombo in 2025 wrapped up on a high note as chicks continued to grow and more juveniles and non-breeding adults started showing up in larger numbers on the beaches. This would be the first time the juveniles and non-breeding adults were back from being at sea since last austral summer/fall, around the time of our March 2025 field work trip. As the field crew packed up and left the field station, we observed more unsupervised chicks alone at their nests. Maturing chicks are less vulnerable to predation and can regulate their body temperature more efficiently, allowing both parents to forage at the same time. This signals the change from the guard stage of chick rearing where one parent is present to the post-guard stage of chick rearing.
Watching the adults go from laying eggs to hatching chicks to feeding large chicks remains to be an inspiring process to witness. Much of the work the field crew did during this time was tracking the growth and survival of eggs and chicks from various nests. Collecting data on nest survival is helpful in understanding why which nests succeed and which fail.
Tagging updates
The crew also deployed over 40 AxyTrek bio logging tags on adults that have GPS, accelerometers, and time-depth recording capabilities. These tags are invaluable as they give researchers a detailed understanding of where penguins forage, why they might select those foraging locations, and when they encounter prey. Understanding penguin foraging behaviors as they are rearing chicks is essential for linking reproductive success with movement ecology. Abrahms lab graduate students Meredith Honig and Erik Johansson are using much of these data in their PhD dissertations.
Weighbridge updates
Every year, our field crews put out penguin weighbridges to collect penguin weights as individuals cross them. If one of the penguins is involved in the study, the weighbridges automatically reads the radio-frequency identification tag (RFID) inserted in the penguin’s foot at the time of entering the penguin into the study. With this technology, we can understand more about penguin weights when coming to and from the sea and sometimes link those weights to specific penguins.
This season we took down a new weighbridge design to test. We started the setup of our two scales in a straight line to compare this new scale design to one we are familiar with. Once we were able to determine that the scales were taking similar weights, we deployed both scales in a staggered fashion, so each penguin only goes over one scale while encouraging better flow of penguin traffic through the scale area. So far the staggered scale setup is working great.
While we struggled to get the weighbridges to read penguin RFIDs last season, modifications made to RFID antenna in the weighbridges this season led to much higher RFID reading rates. So far ≈4% of weighbridge crossings picked up an RFID reading out of 64,000 crossings, which is much better compared to previous years. This is news for future data collection and research utilizing these penguin weights.
Final thoughts
Overall, the austral spring field season was largely a success. As the austral summer field crew settles in and continues data collection, we look forward to more updates on our study nests, the weighbridges, and understanding where the penguins are foraging!
