Jeremy, thanks to an alert from the CahowCams, has averted a potentially disastrous Tropicbird (longtail) invasion of the CahowCam2 burrow.
Over the past 14 years, the 24/7 live streams, generated by the CahowCam’s on Nonsuch Island have been monitored round the clock during the 6+ month nesting season by our Nonsuch Expeditions and DENR Teams, dedicated Cam volunteers, and crowd-sourced followers from around the world.
During this time we have been able to monitor and log the intimate nesting behaviors and other activities of the critically endangered Bermuda Petrels or “Cahows” that would otherwise be impossible to observe.
This season, increased visits to the CahowCam burrows, by Cahows suspected to be other than the resident pair has raised questions about what happens when a Colony is so successful that the population expands faster than new burrows can be built.
This year we have documented multiple occasions when prospecting Cahows, obviously looking for an empty nest, enter the CahowCam 1 and 2 nests and instead of simply moving on to find an empty one in the neighborhood (perhaps due to the lack thereof) have remained and interacted with the resident parent(s) and/or the chick.
This has actually led to questions about the paternity of the current CahowCam2 chick which we are addressing as part of a study with our Genomics partners BioQuest, (which will be the subject of future posts), and has led to multiple fights between the adults.
The LiveStreams have allowed our regular observers to gain an understanding of what normal feeding visit behaviors should look like, and over the past few nights, what appeared at first to be the parents returning, was in at least one case prospecting birds that spent a few hours somewhat aggressively attempting to brood and harass, but not feed, the chick.
Then at one point during the night of the 21st an aggressive prospector was joined by a second Cahow, (which may have been the resident female), which it attempted to mate with, and had an altercation.
Jeremy and I have been monitoring this nightly, and as one adult did not leave back out to sea on the morning of the 23rd and decided to stay in the nest for the day (which happens rarely), it gave us the opportunity to identify which bird it was. Therefore around 10 am, we were on the phone deciding if we should commit yet another of our Sundays to going back out to Nonsuch to catch it and get the band ID#.
As we were jointly watching online, shockingly, a Tropicbird entered the nest, fought briefly with the adult, and started harassing the chick.
Once it started attacking the chick, the much smaller Cahow bravely lunged at it before being chased in to the tunnel, leaving the Tropicbird sitting on top of the chick.
As we had already lost a few Cahow chicks this year on the outer nesting islands to prospecting Tropicbirds that will kill the chick and takeover any nest that they can get into, Jeremy immediately dropped everything and raced to his boat to try to get to Nonsuch in time to interrupt this impending fatality…
In the early days of the Cahow recovery program, up to 2/3 of all of the Cahow chicks every season were being lost in this way until Dr. David Wingate, Jeremy’s predecessor, developed “Baffles” wooden barriers cut to block the more obvious ocean-facing burrows, which have a hole in them just large enough for Cahows to squeeze into, but too small for the usually larger full grown Tropicbirds to fit through.
These usually work, however as Jeremy has documented recently, and happened again today, persistent, smaller than average Tropicbirds can sometimes squeeze their way in and try to take over the nest, often killing whatever they find inside.
Ultimately Jeremy made it all the way from his home in Jenning’s land, to his boat in Flatts inlet, raced along a rough north shore and across Castle Harbour, and onto Nonsuch in a record 35 minutes and was able to extract the Tropicbird from the nest (which was sitting on top of, and had the chicks down in its beak) just in time to save our chick!
Zephyr, defending her sibling chick.
The adult Cahow in the nest was found as suspected to be a young female prospector (which by its presence stalled the Tropicbird long enough to save the chick), so Jeremy relocated it to an empty burrow further up the hillside, which it could claim as its own. When Jeremy was able to return home to check his banding spreadsheet and compare the band number (E0750) of the prospecting Cahow that had been with the chick, it was discovered that it had fledged as a chick from this very nest on June 12th, 2020, and named "Zephyr" by his daughter Lizzy Madeiros!
So “Zephyr” had returned just in time to save her Sibling!
To help reduce future Tropicbird invasion attempts, Jeremy then placed a mound of scurvy grass to make the entrance less visible to prospecting Tropicbirds from the air, a strategy that seems to be working on similarly exposed nest entrances on the outer islands, as unlike Cahows they are not able to walk properly / explore once on the ground and literally need to see their target from the air, and try to crashland into their nest openings.
So, the CahowCams continue to answer questions, and along with Jeremy, today at least, helped save the day…
The Nonsuch Expeditions, including the CahowCams, this website, and the extensive conservation work that we do (much of which isn’t publicly mentioned) are independently funded, and remain underfunded. If you would like to support these efforts, become a Patron, or perhaps sponsor a specific project please consider donating via the Ocean Foundation or contact us for more information/opportunities.