Long Term Effects Regarding Late 1960s Eastern Spruce Budworm Outbreak

One of the finest pieces of work in the field of ornithology that I have found was begun in the late 1960s and the effects are still being seen today, including even more research potential regarding the eastern spruce budworm.

One can only imagine that never has such material led to wide reaching data as this, but it continues to excite as well as direct us into more extensive information than thought possible even a half decade later.  History is being written regarding this, even this far in the future with additional crossbill subspecies.

I shall touch upon the highlights and try to fill in the blanks regarding modern eBird data gleaned through public information, as well as include what we may expect in the future with global warming continuing to thwart the avian world.  It is common knowledge that many species of animals, not just birds, are moving in a north and easterly direction.  It will both be interesting and likely shocking to see what the next half century will bring, especially regarding the survival of both generalist and specialist birds, especially along mountain ranges where the crossbills are even likelier to wander into the deep southwestern states and Mexico.

Numerous small scale studies have been put together and expounded upon with then trending spruce budworm defoliation, Christmas Bird Count (CBC), and Breeding Bird Survey (BBS) data as a junction of the original phenomena.

It was never dreamed initially that this information would reach such heights in the investigation process, nor that it would affect the movement of seven distinct species by the time it was considered at an end.

It was not suspected that global warming or climate change really existed at the time or how quickly the forward motion of the laying of eggs by the eastern spruce budworm, followed by climactic action could lead to such a large scale defoliation.

Because these infestations became larger over time with the right recipe--warm dry springs and large scale conifer forest with the correct percentage of white spruce, balsam fir, and black spruce--one infestation quickly flowed into another, only enlarging.

As the years passed, one pesticide replaced another to attempt to kill off the budworm, of course to no avail.  Replanting the forest was attempted with likely infected seedlings, large scale fire suppression, and extensive clear cutting all around the eastern portion of the US, where many individuals depended upon wood heat over the winter from southern Canadian provinces, including the New England states.

To make a long story short, there was a forest collapse and many of the dead trees were felled.  Outbreaks were minimized with the planting of least susceptible trees like jack pines and black spruce, but this change also affected birds that preferred living and nesting within the balsam fir.  At that time, the rare irruptions of Black-capped Chickadee and Red-breasted Nuthatch, occurred in a synchronized manner, and it was assumed that since food sources collapsed, the affected birds would seek sustenance elsewhere.

Ebird as well as CBC data was utilized, picking up trends of irruptions which went from every other year to some that were more or less often, and affected other birds such as Red- and White-winged Crossbills, Evening Grosbeak, Pine Siskin, and Purple Finch.  The finches and grosbeaks followed the increase of the budworm expansion, which the other five species increased and decreased inversely.

The interesting thing about the Black-capped Chickadee irruptions was the fact that it was discovered that they shared three contact zones with the Carolina Chickadee and hybridized as intermediate species, as a result of the events.

The Boreal Chickadee, which is even more northern than the other two, also got in on the action and periodically came to southern New England, New York and Pennsylvania as well as the south central states as another irruptive species.

The Pine Grosbeak was believed to have come south at the end of the budworm infestation and it was caused by destruction of the Boreal Forest.  This was why it appears that it has not been continual.

The crossbills are believed to have declined due to large scale budworm destruction, but these days, Red Crossbills have a much larger range than the White-winged Crossbill ever did with their current ten species.  The white-winged Crossbill never had such a large irruptive pattern.

There were also spruce budworm warblers, like the Bay-breasted, Blackpoll, Cape May, and Tennessee Warblers.  They will still periodically show up during outbreaks in the southern states.

So, in a nutshell, we are still observing from time to time, the aftereffects of many birds that were initially affected by the change in their habitats.  They are still predisposed to wander as irruptives as the circumstances dictate.

I wish to thank Nicholas Bolgiano, Zach, Falls, Erskine, Morse, Crawford, Jennings, Hagan, Hussell, Patten, Burger, Sauer, Blais, Raske, Kettela, and the many other individuals that invested the thousands of man hours in order for us all to benefit from their tireless efforts for the good of ornithology.  You are all a credit to your schools and your research papers that opened the doors for us all.  May we remotely aspire to your teachings.

For More Information on the Red-breasted Nuthatch:

https://debhirt.blogspot.com/2018/10/oklahoma-irruptive-species-profile-red.html

For More Information on the Pine Siskin:

https://debhirt.blogspot.com/2018/10/oklahoma-irruptive-species-profile-pine.html