Huge Numbers of Redpolls

Observation by Richard Thoman

Redpolls have been extremely numerous all winter. While we sometimes see large numbers at the feeder in February and March, this winter the large numbers appeared in November and have continued with few breaks. The number of redpolls has not seem to vary depending much on whether it's unusually warm or cold and is frequently in excess of 50 birds around the feeder at any one time. Chickadees and nuthatches have been more infrequently seen at the feeder, presumably from lack of access.

LEO says:

Thanks Rick for this observation. Here in Anchorage it has also been a cold winter and we have also seen record snow. A wind storm early in the winter blew a lot of the seed off the trees (see attached post, "Abundance of seeds on snow"). I wonder if that might be a factor? We have also noticed huge flock of redpolls at our house, mobbing the feeders and emptying three in a single day (see photo)! We have also seen chickadees and nut hatches, but small numbers in comparison. According to the National Audubon Society, common redpolls typically feed on seeds and some insects.

"Feeds on catkins, seeds, and buds of willows, alders, and birches, small conifer seeds, also seeds of many weeds and grasses. Also eats insects, mainly in summer."

There was a report of February 10, 2024 on social media (X) from the USFWS about an increase in dead or sick redpolls in the Fairbanks area (see post image). We have asked Kimberlee Beckmen DVM with the Alaska Department of Fish and Game for a consult. M. Brubaker

Comment by Kimberlee Beckmen:

ADFG has observed mass mortality events of redpolls in January in the Fairbanks area, coinciding with severe cold for several days (below -40F). In several years, 2005, 2009, and 2024, we’ve documented the majority of mortalities (when more than 1 bird per feeder was found at the same time) was attributed to an intestinal bacteria infection similar to Salmonella, specifically enteritis from Escherichia albertii infection. When there is only 1 bird per day at a feeder and in 2017 and 2021, most mortalities were due to head trauma. This leads me to believe that E. albertii is a normal commensal bacteria in the gut of redpolls, but when they become highly stressed (severe cold, competition for food, etc.) the bird’s immune system can become overwhelmed and they succumb. It is also likely that when there are increased numbers of redpolls in the Interior, there is a greater likelihood that more dead birds would be discovered and reported but there is definitely a correlation with days of deep cold, always January, and only in the Interior.

I would also point out that prior to our first discovery of this pathogen, E. albertii, in 2005, it was known only as a pathogen in contaminated baby formula and responsible for human deaths. It has since been found in other wildlife but is still considered a zoonotic pathogen so when we see an outbreak we warn people not to handle dead birds, prevent pets from contact with wild birds, especially beware of cats bringing in dead birds that could contaminate the home and put children or immunosuppressed individuals at risk. I also advised that feeders where dead birds were found to be removed, disinfected and any droppings/seeds under the feeder be removed/disposed of and the area disinfected.

Comment from Gemini:

The observations linked to this report highlight a recurring pattern of redpoll population fluctuations and associated health concerns in Alaska. The abundance of seeds on snow due to the wind storm, as mentioned in the linked observation, could be a contributing factor to the large redpoll gathering. This aligns with previous observations such as the 2019 influx of redpolls attributed to a plentiful birch seed crop. However, the reports of sick and dead redpolls, particularly in relation to extreme cold, raise concerns about potential disease outbreaks. The observations from 2022 and the current report from Fairbanks highlight the recurring issue of redpoll mortality, potentially linked to E. albertii infection as explained by Kimberlee Beckmen. The correlation between severe cold, increased redpoll numbers, and mortality events suggests that environmental stressors and disease might be intertwined. This situation underscores the importance of monitoring redpoll populations and implementing precautions, as advised by Dr. Beckmen, to minimize risks to both birds and human health.