Cold Weather Kills Most Birds

Dead Birds Falling

On October 8th a resident of Pacifica California reported that 2 birds fell dead from the sky onto his deck. That would startle anyone and raised grave concerns. People began suggesting possible causes: a mid-air collision, West Nile virus, rat poison, wildfire smoke, and of course the climate crisis. Some pointed out they had found a dead bird in their yard. Others referenced a massive die-off of migrating birds in early September over Colorado and New Mexico suggesting thousands, maybe a million birds had died. The speculated cause of death was wildfire smoke, starvation and a cold snap that dropped temperatures from 90°F to near freezing in a matter of hours. Sky-is-falling fears and fearing a “ bird flockalypse” one person wrote, “if birds are dying, we humans are next”.

 

Good scientists must examine all likely factors. So, I investigated the stories behind most documented bird die-offs.  For the case of a single dead bird found in someone’s yard, that bird may have died from disease, flown into a window, or simply died of old age. Most of our sparrows, warblers and hummingbirds don’t live longer than 13 years. Twenty-five to fifty percent of young birds die in their first year.

 

California asks people who find dead birds to report them to local vector control agencies so the birds can be tested for disease, West Nile Virus in particular. For the year 2020, to date about 5200 dead birds have been reported in California, a fourth of which were tested. Only 320 have had the virus, while most died of unknown causes. (Mass die-off of 10 or more birds are not included in their reports.) Los Angeles county reports the most dead birds, while rural Sierra County reports none. That suggests higher population centers with more eyes find more dead birds.

 

In contrast, the die-off of hundreds and thousands of birds, often during migration requires very different explanations. Good scientists must place such unusual events into a historical context. Was the September 2020 die-off in the southwest so historically rare that we can attribute it to how humans have recently altered our environment? Or, are such die-offs relatively common occurrences. Scientists calculate millions of birds die each year during migration in North America. We just don’t know all the causes, or what percentage of dead birds are actually observed.

 

A 2007 scientific paper reviewed reported bird die-offs across the globe and major die-offs were observed more than once a decade for the past 120 years. Some happen during spring or fall migration, other die-offs happen while on the breeding grounds. Most are associated with cold weather. On New Year’s Eve night in 2011, people reported dead black birds “raining” from the sky around an Arkansas town. People blamed everything from secret military testing and UFOs to bad weather. Investigations later determined 5000+ birds had died from blunt force trauma, which confirmed reports that birds were flying into buildings and towers. Apparently, someone attempted to scare away a roost of a million black birds, which are agricultural pests, with fireworks. Black birds have poor night vision which explains their collisions with houses.

The most common cause of other cases of bird deaths was bad weather - heavy rains, cold or snow. For example, a sudden cold spell across southern Germany, Austria and Hungary caused birds numbed by the cold to fall from the sky. Residents eagerly brought still living birds inside to warm, then loaded 89,000 birds onto planes and trains, sending them south to a warmer Venice, from which birds continued their migration.

 

In March 1904, a small town in Minnesota reported dead birds falling. Investigations determined nearly a million birds, all Lapland Longspurs, died during a heavy rainstorm. Over 750,000 birds were counted on just 2 small lakes that were still covered with winter ice. Autopsies determined most birds died from blunt force trauma as birds crashed into the ice or buildings.

Migratory deaths of thousands of birds this September in southwest USA likewise, appear to be driven by a cold snap. USGS experts have indeed told me that the best explanation is still a sudden cold snap that dropped temperatures from the 90s to near 30 F, killing birds already stressed by the rigors of migration. My analysis of archived EPA air quality doesn’t suggest smoke particulates coincided with that die-off, but officials have not yet ruled out wildfire smoke. Corpses are still being autopsied and whether or not there is lung damage could implicate wildfire smoke. 

I suspect the most likely cause of the 2 birds falling dead from the sky in Pacifica was due to exhaustion from flying out over the ocean and trying to return to land. I have been on pelagic bird trips miles from shore where exhausted land birds flop down on our boat. Several studies have been performed on the Farallon Islands which are 26 miles offshore due west of Pacifica. Several studies note weather conditions, such as offshore winds that we naturally experience this time of year (ie Diablo Winds that also spread human ignited fires), cause birds to veer off course and fly out to sea. They can be further confused by the offshore fog bank. Many of the birds having arrived on the Farallons are later observed to be headed back to shore, suggesting they are guided to our coast if they can see land when not obscured by fog. Furthermore most of the Farallon birds are young birds born that summer and are typically less efficient at finding food and more likely to become emaciated after an extended overseas flight. 

Of course as for all tragedies, media like the Guardian always blame the “climate crisis”, and downplay cold weather.  They push flockalyptic fears even though there is no support to suggest the sky-is-falling or ecosystems are collapsing. Birds have indeed suffered from loss of habitat, overhunting and window crashes. Fortunately, people are working to change that. I removed my bird feeder because it attracted birds that flew into my windows. But it is natural weather events that have caused most major die-offs. Yet still birds have risked bad weather events for thousands of years in order to enjoy the benefits of migration.

 

from What’s natural? column

Published in Battle Born Media October 28, 2020 

 

Greenland and the 1950s Climate Consensus

Glaciers around the world reached their greatest size in four thousand years by 1850. Then abruptly the world began to warm. Arctic sea ice lost 40% of its thickness by 1940. Around the Arctic island of Spitsbergen melting sea ice allowed shipping season to lengthen from 3 months to 7 by 1940, meanwhile 400 additional square miles of sea ice was melting along the Russian coasts. By 1950, 96% of Europe’s glaciers were retreating and small glaciers had simply disappeared. In the tropics, Africa’s Kilimanjaro’s iconic glaciers were also shrinking alarmingly.

 

In the far north, pine forests couldn’t reproduce between 1850 and 1900 due to the cold. But with warming, all age classes of seedlings proliferated. Tree-line rose by about 70 feet in a few decades. Plants were flowering earlier, and seeds and berries ripened earlier. Atlantic cod moved northward creating a new Greenland fishery and several southern bird species moved into Iceland.

 

 

This warmth was an extraordinary climate reversal and scientists sought to understand that change. By the 1950s a foremost glacier expert, H.W. Ahlmann, stated the growing consensus the dramatic warming was due to “an increased transfer of heat through the atmosphere by a strengthening of the winds carrying heat from southern parts to the Arctic."  Today’s top climate scientists are observing similar natural climate change that pushes warm winds and warm ocean currents northward, melting the Arctic once again. 

 

To be fair, In the 1940s the British engineer G.S. Callendar also suggested CO2-global warming was melting glaciers. But he was a lone voice and peer-reviewers had refused to publish his paper attributing CO2-global warming for Kilimanjaro’s melting glaciers.

 

Today there is growing scientific support for the theories that changing winds cause decades of warming or cooling in the Arctic. One measure of naturally shifting winds is called the North Atlantic Oscillation (NAO) index. The NAO alternates between a positive phase in which westerly winds increase, bringing warmer winters to western Europe. Switching to its negative phase, the westerly winds decline causing western Europe to cool, but that phase also causes warmer winds to blow from south to north more frequently.  Scientists admit that as much as 100% of observed climate change could be due to that natural variability.

 

As political battles over who controls energy policies intensified, interest in fossil fuels and CO2-global warming theory was revived. Scientists promoting CO2-global warming exhumed Callendar’s private papers and elevated his status to a founding hero of global warming theory. A few scientists believed that rising CO2 could affect the winds and the phase of the NAO. Because the  positive NAO had produced strong westerly winds that warmed much of Europe and Asia, they predicted the current positive NAO would continue and further intensify global warming.

 

But that hypothesis failed quickly. The NAO reversed to its negative phase as the 21st century began. That caused westerly winds to weaken. That produced more persistent blocking high pressure systems and a wavier jet stream as seen in the diagram.  Blocking weather systems are slower moving than normal storms and force the prevailing winds and other storms to move around them. This was outlined, again, in the 1950s by climate scientists who pioneered our present understanding of blocking systems. Weather satellites now confirm those weather effects. They also showed when early 20th century blocking systems forced warm air from the south to pass over Greenland, surface temperatures rose 10° to 12°C above normal. 

 

 

 

In the diagram orange colors are warmer and blue colors are cooler. Blocking systems in the Pacific push warmer air (orange) into Alaska and draw cold air into the southern USA. Thus, Alaskan temperatures are sometimes higher than northern Florida. Likewise, blocking in the Atlantic pushed warm air over Greenland causing extreme melting but brought a cold snap to Europe. Americans became aware of the power of a negative NAO and blocking when a weak hurricane was prevented from normally moving out to sea. Instead it was diverted into New Jersey, transforming into the devastating Superstorm Sandy. In 2019, a warm air mass from the baking Sahara Desert moved northward. Crossing Europe, the Saharan air brought record high temperatures. Continuing northward, that warm air then caused Greenland’s 7th greatest period of melting since 1978.

 

The theory that the NAO and shifting winds create the conditions that drive Greenland’s warming and cooling is supported by all observable evidence. Greenland lost ice in the 1930s then gained ice in the 1970s and 80s. Although Greenland’s ice has been melting extensively in recent decades, that melt rate is now slowing and the shifting NAO suggests the ice will rebound. In contrast, the competing CO2-global warming theory suggests as CO2 continues to rise, Greenland’s ice will increasingly melt and dramatically raise sea levels. That theory has prompted calls to abandon our coastlines and invest in managed retreat. But before you panic, know your climate history and listen to the science. All the science!

Published in Battle Born Media newspapers 10-13-2020 

Contact: naturalclimatechange@earthlink.net