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Avian Flu Along Colorado’s Front Range – “The Stuff of Bad Dreams” for Wildlife Watchers and Chicken Farmers

January 9, 2023

Northern Harrier picking over the remains of dead duck. Saturday, January 7, 2023 along S. Platte River Trail in Thornton, Colorado, in an area where avian flu is rampant. Was the duck a victim of this epidemic?

Nationwide, 57.8 million birds in 47 states have either died or been culled due to the virus, according to the Centers for Disease Control and Prevention. The previous record was set in 2015 when the avian flu outbreak killed off 50.5 million birds in 21 states.

Covid-19 among human populations, avian flu among birds, domestic and wild.

On Saturday (January 7, 2023), out for my weekly 3-4 mile walk to photograph birds along the South Platte River ten-fifteen miles north of Denver, I came across a dead duck on the walkway near the confluence of the South Platte and Clear Creek. Its beak suggested to me that it was more than likely a Northern Shoveler – a male, given the coloring of the remaining feathers. I stopped for a few minutes, wondering about the cause of death. A coyote? an eagle or big hawk? It was only much later that the idea that it might have died of avian flu – the formal name of which is Highly Pathogenic Avian Influenza (HPAI) came to mind.

After talking to a man walking his dog, I turned back to note that a hawk was pecking away at the ducks remains; as it was concentrating on its meal and not on me, I was able to get some good shots of it; it was easily identified as a female Northern Harrier. I posted a photo of the Harrier standing over its meal on social media. Above, another shot from the same series.

A week earlier, I’d seen another seen, suggestive but frankly not one that one could draw any firm conclusions to. A mallard, feet up, was floating downstream along the South Platte, near the spot where later I saw the Harrier feasting.

Of course there could me any number of reasons why these two ducks died and the bottom line is I’ll never really know. But an in-depth article that appeared at the on-line website of the Colorado Sun by Michael Booth, Tamara Chuang and Joshua Perry leads me to suggest that avian flu could have easily been the killer. The article includes a map done by the Colorado Department of Agriculture. It has mapped all the locations of HPAI it could document on its site. But “the Sun” article notes that the count is at best a kind of sampling as the department, given its limited resources and the extensive spread of the disease, is only testing in the most impacted areas. And as it turns out, among those highly impacted areas is precisely the stretch along the S. Platte north of Denver where I noted two dead ducks over a period of ten days.

Victims of Avian Flu noted by the state’s Department of Agriculture reported on their on-line site along with dates:

* 04/26/22 HPAI confirmed in 1 wild bird – Bald eagle
* 10/06/22 HPAI confirmed in 1 wild bird – Canada goose
* 10/26/22 HPAI confirmed in 1 wild bird – Great Horned Owl
* 11/9/22 HPAI confirmed in 1 wild bird – Canada goose
* 12/5/22 HPAI confirmed in 1 wild bird – Bald Eagle
* 12/15/22 HPAI confirmed in 3 wild birds – Common merganser
* 12/30/22 HPAI confirmed in 1 wild bird – Red tailed hawk

Note how the dates given go from late April of 2022 to last week (the December 30 figure). Most of those affected are either raptors or other big birds (Canada Geese) although a Common Merganser is included in this bunch. Are the mallard and Northern Shoveler carcases I saw a part of the diseased pack as well? Note that these are only figures for one Colorado county. Needless to say, don’t know.

HPAI seems to show no preference for genetically close enough domestic and wild birds. Regardless, the outbreak is already considered Colorado’s “worst-ever” case of avian flu and already the statistics – these for the state of Colorado along – are alarming. It includes:

  • nearly 6.4 million poultry deaths
  • a growing number of wild birds with increased targeting raptors
  • especially targeted is the state’s bald eagle population of between 250-300 pairs
  • a decline in monthly domestic poultry egg production to about 41.1 million eggs from a figure almost three times that number; price of eggs soaring.

Concerning how HPAI has devastated commercial egg production in the state, the Sun article notes:

Colorado’s 6 million egg-laying chickens typically produce about 1.56 billion eggs per year. In 2022, that number fell to less than 1 billion eggs. After slaughters of 260,000 and 1.35 million birds in Weld County in December, Colorado has now seen essentially its entire commercial egg flock wiped out in less than a year. …

It appears this devastation has far from run its course. Both state and national officials admit that they do not know how to stop the flu’s spread among migratory bird;  they expect the epidemic to rage on through early winter until birds settle into winter grounds with very possibly mass die-offs likely to pick up again in the spring as flocks of snow geese, Canada geese and other common birds head back north.

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