The Decline in Bird Biodiversity

The nature trail

    I started birdwatching 7 years ago when I was 6-7. At that age, I didn't know much about birdwatching or how many bird species there were in the world. I spotted birds by going out to a nearby park filled with creeks, wooded areas, and marshland and looking for them with my naked eye. The American Goldfinch was the first "elusive" bird species I learned the name of. I was also amazed by the vibrant blue hues of the Blue Jay and learned about feather iridescence at an early age from Common Grackles and pigeons. Surprisingly, I also managed to spot warblers at that park, seeing the Yellow Warbler. 

    After about two years, I learned the primary bird species in my area and birdwatching tips, so I started going to a nearby nature trail that surrounded a lake. This nature trail had dense forest cover and was situated next to a river, so it was a phenomenal place to go birdwatching during migration months. When I went there for the first time, it was fortunately right in the middle of spring migration, so I spotted multiple wood warblers, vireos, and wrens. Just to give an idea, I saw a Red-eyed vireo foraging at eye level, spotted multiple baby wrens, and saw so many warblers I couldn't even count the number of species. I even saw a Green Heron! 

    Stunned by the sheer abundance of birds I spotted that day, I kept coming to the hotspot frequently. However, as time passed, I noticed that the number of bird species kept decreasing and decreasing. There were more backyard birds than forest birds, and different heron species did not appear for quite some time. While I took the first trip there to be beginner's luck, I consistently kept seeing fewer and fewer species. As two years passed, nearly the whole trail was inhabited by backyard birds, such as Song Sparrows, Red-Winged Blackbirds, American Robins, and Common Grackles. When I went right in the middle of spring/fall migration, I would see a couple yellow-rumped warblers, but nothing special. This was initially very confusing to me since I expected that if I had birdwatched for such a long time, then I would be keener, more knowledgeable, and overall a better birdwatcher than I was before. The bird species at the nature trail today are quite different than the set of bird species over there 5 years ago. The entire place is filled with squirrels, Song Sparrows, Gray Catbirds,  Gulls, and Cardinals. There are few rarities left. To see whether other people experienced the same phenomenon, I went onto eBird Hotspots and checked the bird sightings in the nature trail hotspot area. Indeed, as I scrolled down all the way down to sightings in 2018, multiple birders spotted 20-30 species in just 1 hour over there. For example, one individual could spot 5 warbler species,

    3 Empidonax flycatchers, and 2 Vireo species. Clearly, numerous bird species were present on the nature trail 5 years ago. To confirm my hypothesis that bird biodiversity had decreased, at least in this birding hotspot, I looked at sightings from 2021-2023. To maintain high accuracy, I chose the bird checklist with the highest number of bird species recorded. In this case, in the time range of the past 2.5 years, the most comprehensive bird checklist had only 23 species. Compare that to the 34 species bird checklist from 5 to 2.5 years ago! Let's take a look at the 23-species bird checklist:

    The rest of the species on this checklist were backyard birds. While this checklist had some remarkable species, it still paled in contrast to the golden age of birding a few years back. Another notable comparison worth reviewing is the date the list was recorded, which in this case was on the end of the spectrum:

    2 years ago, at the very end of the timeline! No wonder there were so many rarities present. While this decline may be accredited to habitat destruction or human activities, I have noticed nothing of the sort, except an increase in the number of joggers in the area. I do not believe jogging can have such a significant impact on bird biodiversity. However, I do not know the whole story of the nature trail, so let's refer to more knowledgeable resources such as the Cornell Lab of Ornithology:

A clear negative trend for land birds and shore birds can be seen in this graph, and I witnessed a small section of that. For the increase in dabbling ducks and water birds, look at this graph:

    Rising sea levels offer more habitat for such birds. However, the opposite story is shown for shorebird and sea duck populations. Shorebirds make nests on shorelines, as the name indicates, so when sea levels rise, they wipe out the nests. The decline in sea duck populations is due to a combination of causes; sea ducks are often hunted, they are difficult species to give accurate counts on, and overfishing decreases food sources for these birds. Whatever the reasons, the number of forest birds has been steadily dwindling. Habitat destruction and human prevalence is the root cause of all these problems.

    Now, here are some solutions and small steps we can take to stop this. As individuals, we can plant native trees and shrubs, provide food and water, and put up nest boxes for threatened species. However, these are all small steps that a small part of the population will follow. The real damage is from companies, governments, and institutions. Therefore, we can petition these large groups to limit and halt their impact on bird habitat and petition governments to keep more land aside for birds. If this destructive trend continues, there will no longer be any beautiful birds left in the world for birdwatchers to spot.