Update: Influx of sick Brandt’s Cormorants
As we enter into an already busy spring season I wanted to take a few minutes to say thank you to everyone who supported IBRRC during the last year and more recently during the pelican event that we experienced this winter. We enter into spring with a smaller but similar influx of sick and disoriented birds. This time they are Brandt’s Cormorants. We have about 25 of them at the center right now and are expecting more soon. Most of these birds have come from the South Bay Area: Alviso and San Jose and some from Monterey as well. Most are adults in beautiful breeding plumage and all are in a weakened state but respond well to a treatment of fluid therapy and lots of fish. We also worm them as a courtesy to them to help them get back on track. All seabirds have internal and sometimes external parasites and although these are normal, they can aid in weakening a weak bird even more.
We asked the biologists at PRBO Conservation Science about Brandt’s Cormorants and how they should be acting this time of year. Here is a bit of what they communicated back to us on April 16.
From Pete Warzybok, Farallon Islands Biologist, PRBO Conservation Science:
“We have the largest breeding colony in the area on the Farallones, but the birds have been AWOL all spring. Usually we would have birds setting up nests by now, but they haven’t really even been around the island so far. My guess is that they are hanging out along the coast and foraging near shore. This also happened last year and we ended up with the smallest breeding population of Brandt’s and lowest reproductive success in almost 20 years. Similar failures were observed at colonies throughout northern California and Oregon. I hope that this is not the first sign of another colony failure.
We have certainly had a lot of wind out here the last few weeks and the ocean has really been churned up. In fact this is the windiest spring that I have experienced since I started here in 2000. It has more or less been blowing 25-30 continuously since the third week of March with few periods of relaxation. That might help to explain why the corms are not building nests. Cormies are visual predators, so the high winds and choppy seas might also make foraging difficult, resulting in the skinny birds that have been brought in to you. Although they should be able to dive below the chop, there just might not be much there to feed on. Right now I would imagine that there is a lot of upwelling with all this wind, but it doesn’t appear to be that productive. There has been very little krill seen out here and the water is still incredibly clear. This is typically not a good sign and generally indicates that there is little zooplankton to support the forage fishes and squid that the Brandt’s rely on.”
From April 17th Russell Bradley, M.Sc., Farallon Program Manager, PRBO Conservation Science:
“We have seen zero nesting activity yet out here, with intermittent low numbers of roosting birds, very few (if any) in colonies. No dead Brandt’s have been seen out here. Pelagic cormorants are attending sites, though not breeding yet. The Brandt’s response is very puzzling, as Cassin’s Auklets are breeding full swing and murre pre-breeding attendance has been strong. Definitely some mixed signals.”
So, IBRRC’s present theory is that these groundings of thin and weak adult cormorants are a combination of high winds, choppy seas and lack of fish. No signs of disease, seizures or anything else that would indicate something like domoic acid or Newcastle’s disease has been observed. Is it caused by climate change? Well, our climate is changing and we are seeing more of these die offs. In my 38 years plus of doing seabird rehabilitation along the coast of CA I have experienced die offs of scoters, loons, pelicans and some other species but they are clearly happening at an increased rate. I do want to point out that even as early as 50 years ago there were not rehab groups like IBRRC who took in these birds nor were there organizations like PRBO who studied seabird population levels so these types of “natural” or unnatural events may have occurred and go unnoticed. Who knows? But for sure, they are happening now. The weather and the seas are changing and that means that the animals that rely on them will have to deal with that also as we saw with the pelicans that experienced and unseasonable cold flash in Oregon and Northern CA this winter and now the cormorants.
We will keep you updated on the current situation as it changes.
– Jay Holcomb, IBRRC, Director