Field Journal #5 ... My First Causeway Park Experience

Date --- 4/4/2021
Start Time --- 1:15 AM
End Time --- 3:15 PM
Location --- Causeway Park, Colchester, VT 05446
Weather --- (Temperature) = 45 degrees Fahrenheit, or ~ 7 degrees Celsius ... (Wind) = ~ 5mph N ... (Precipitation) = none. Sunny with low level of cloud cover.
Habitats --- Smooth mud/dirt trail for 0.5 miles, w/ slow moving, lentic brooks on both sides of walkway. Wooded areas extend out on land to W. Eventually transitioned to wetland and then open water, with walkway (or Causeway) extending out for miles across Lake Champlain w/ rocks and solid material serving as the barrier between land and lake.

A few weeks ago, I was attending Professor Trish O'Kane's office hours and I had asked where I could have good "birding" sessions; as spring continues to establish itself, the general weather has continued to gradually warm up. She had suggested the Causeway, located in Colchester extending outward into Lake Champlain. Last week, I ended up making it out to the Green Mountain Audubon Center and the Birds of Vermont Museum in Huntington, VT; my partner and I didn't observe many birds, but the trails (including a tree overtop a brook that served as a bench, and another overturned tree whose root system showed a masterpiece of a mural that spanned about 20 feet wide ... we stared at its complexities for about 15 minutes before continuing) were very calming and splendid to spend time in. Today, I visited the Causeway for the very first time, an experience I'll never forget ... I witnessed multiple new bird species such as a group of Tree Swallow and a pair of Bufflehead. As soon as I encountered the open water, a Herring Gull (another species I had never seen or successfully ID'ed before) swam alongside me for approximately 15 minutes as I strolled along the path. I declared us buds, and shortly following this named him Bugs (videos of him can be found all the way at the bottom of this post, linked to Imgur). An unexpected inhabitant (in my mind), a tiny mink, was spotted on the bridge about three quarters of a mile into the lake before hiding. I had never seen one of these before, and a fisherman on the bridge said the individual and/or a family member(s) must have been the ones eating the fish in buckets on land, to be utilized for bait.

Spring has now fully established itself (last journal was one of the first warm spring-esque days of 2021), as temperatures continue to consistently warm up; this week is predicted to supply Burlington residents with highs of 50s and 60s, partially cloud covered sun and nights nearing and perhaps dipping below water's freezing point of 32 degrees. With sunny conditions and a northward wind like the one felt today, birds are bound to be migrating back north, following the wind and allowing it to guide them in order to conserve energy; I even saw a group of five geese flying back North above me, as well as a few other individuals. However, not all birds that spend time in our area leave for the tail end and very beginning of each year to catch the sun's rays down south. The birds that are commonly observed left behind in the harsh, cold northeast winters include the Black-capped Chickadees (a bird I spotted around a half dozen times), the Northern Cardinals (whose sounds I heard along the wooded area of the path), the Mallards, the woodpecker species (such as the downy, hairy and pileated), the American Crows, both white and red varieties of breasted nuthatch, and other species that aren't as well known to Vermont's native winter wildlife not listed here. Most purposefully stay and stand their ground due to various reasons, but all of these different reasons all fall under one overarching theme; it would simply take an excess of energy, that these wintering birds do not have, in order to relocate anywhere between hundreds to thousands of miles. Birds' metabolisms are sky high as it is, and in WFB 130 lecture about a month ago, these animals were described as living "life on the metabolic edge" due to their high body temperature and water demand, efficient respiration system and a powerful heart and circulatory system. Often, these migratory flights made by the "vacationers" aren't supported by land underneath in case of a weather emergency or turbulent winds; the paths sail above the oceans most times, with no vertical obstructions whatsoever to slow these vicious winds down. At the Causeway where I was, these species that remain behind would most likely shelter in wooded areas, like the dense wooded area around the 0.5 mile path to the water body, in order to shield their light bodies from the harsher weather.

Behavioral adaptations for facing the winter weathers could include being picky about tree cavity selection (in one of my past field journals (FJ#3), I discussed how one paper I read noted that wintering birds prefer southward-facing cavities because of their greater light exposure rate during these months) and food selection (berries and other "insulating" diet items like nuts, seeds, insects and fruits can help a wintering bird retain heat). These cavities are called "microhabitats" due to their rather miniature nature and vast difference that separates it from the external environment. Other behavioral factors include "floofing" to trap warmer air along the body, standing on one leg, facing the wind (in the case of certain gull species), huddling to conserve heat and adjusting posture (WFB 130 lecture, 3/8/2021).

Thinking physiologically about winter birds, my mind is drawn to the bird's legs, one of and in some cases the largest apteria. The arterial, oxygenated blood is run down through vessels in and around the feet, and travels back up in a venous, unoxygenated state. This transfers heat to the regions most susceptible to thermodynamic biological damage. Photoperiod detection and other cyclic rhythms can also induce drastic life stage changes in the bird, which can also alter physiology and thermoregulation mechanisms within these creatures.

The returning migrants could include species such as the Tree Swallows (perhaps coming from the Carolinas, Florida and the northern coast of the Gulf of Mexico ... they will most likely breed across the southern portion of Canada, extending south into the N/NE/NW continental United States and Alaska), the Buffleheads (coming from the SE/S/SW/W United States, heading towards S/SW/W Canada and Alaska); and other birds not witnessed today, such as Vermont's state bird, the Hermit Thrush (winters in SE/S/SW United States, migrates to NE/NW United States respectively; also flies to S Canada and S Alaska to breed). Some birds' wintering ranges overlap a little or a lot with breeding ranges, and migration distance could depend on factors like foraging technique, behavioral aspects of the species and energy conservation. The birds listed within this paragraph have mostly separate breeding and wintering ranges, leading me to infer most of these birds are obligate migrants. Throughout my field journal and birding excursions (specifically this FJ when citing ranges), I have been referencing my field guide ... National Audubon Society Field Guide to North American Birds -- Eastern Region, by Alfred A. Knopf (1994). Often times, the photoperiod increasing (as the Sun shines more and more on the Northern hemisphere as the seasons progressively warm up) prompts these birds to get ready for their journey back to their familiar summer family settings. Other factors could play a role, such as food availability, inability to handle excessive heat (thermoregulate) closer to the Equator and Tropic of Cancer during warmer summer months, the need to beat other birds to prime nesting sites, and winds as mentioned earlier.

Obligate migrants (mentioned in the paragraph above ... birds who migrate on a rather strict schedule and tend not to defer annual migration) are the birds most impacted by the photoperiod change effects described above; most of Vermont's avian population can be described as obligate migrants. There are some benefits that come with arriving at a set time window each and every year like early April (such as arriving before facultative or optional migrators, access to food and claims to nesting), but there are most definitely some detriments. With climate change altering Earth's naturally connected systems, these birds can't depend on the weather being consistently warm and the usual benefits they reap when they arrive to their northern destinations.

For the mini activity, I just calculated the potential approximate mileage for an individual bird based on species ranges, using my field guide and Google Maps "measure distance between points" feature. I am basing this data off of assumptions that A) birds in the SE United States will not migrate northwestward and rather towards NE United States, just like birds in the SW will not migrate northeastward; and B) relative latitude in wintering ranges will determine relative latitude in breeding ranges. This will not be the scenario for all bird individuals and species and I realize this, but it is a rough baseline for these calculations.

1) Black-capped Chickadee (x7 but assume 6 did not migrate ... ranges heavily overlap throughout N United States and S Canada ... therefore x1) ... distance from site (Causeway Park) to Charleston, SC is 550 miles ... 550 miles x 1 individual = 550 miles

2) Dark-eyed Junco (x1 but VT is right in the small-area sweet spot of overlapping ranges, therefore x0) ... 0 miles

3) Downy Woodpecker (x1 but almost entire range, which lies in most of US and some of Canada, overlaps ranges ... therefore x0) ... 0 miles

4) American Robin (x4, but breeding range overlaps heavily in NE United States ... assuming 2 individuals migrated from Lake Okeechobee, FL) ... 1,300 miles x 2 individuals = 2,600 miles

5) Canada Goose (x2, but northeast states like New York and Vermont are excluded from both ranges) ... n/a or incalculable based on source

6) American Crow (x1 and US serves as overlapping range) ... distance from site to Atlanta, GA is 950 miles ... 950 miles x 1 individual = 950 miles

7) Herring Gull (x1 but VT lies right in sweet spot of overlapping ranges, therefore x0) ... 0 miles

8) Bufflehead (x2 ... in Field Guide, says these birds breed in Alaska and S/SW Canada, winter in southern US ... Vermont not included in range whatsoever) ... n/a or incalculable based on source

9) Song Sparrow (x14 ... ranges partially overlap, especially in the NE and more specifically VT ... we'll assume 7 migrated from Charlotte, NC which is 750 miles away) ... 750 miles x 7 individuals = 5,250 miles

10) Tree Swallow (x8, assume 6 arrived from a Gulf Coast city as opposed to the East coast; New Orleans, LA is a 1,400 mile distance) ... 1,400 miles x 6 individuals = 8,400 miles

11) Ring-billed Gull (x3 but NY, VT, ME not included in either range ... assume one pair of these flew up from Washington, D.C. a distance equivalent to 530 miles) ... 530 miles x 2 individuals = 1,060 miles

12) Common Merganser (x2, but VT lies right in the sweet spot of overlapping ranges, therefore x0) ... 0 miles

13) Mallard (x2, VT lies just N of overlapping ranges. Say this romantic couple just arrived from Richmond, VA, 530 miles away) ... 530 miles x 2 = 1,060 miles

TOTAL MILEAGE CALCULATED, in miles ... 550 + 0 + 0 + 2,600 + (n/a) + 950 + 0 + (n/a) + 5,250 + 8,400 + 1,060 + 0 + 1,060 = 19,870 miles. Nearly 20,000 miles are estimated to be accumulated among the observed bird individuals on Sunday, April 4, 2021. Makes you wonder how many miles you've traveled on your feet (not in a vehicle) in your life ...

Once again these are all very rough estimates, with different confounding assumptions. We must also not forget that these distances are straight lines, and it is evident that in the natural world that not many things go directly from point A to point B on their own, whether that be biochemical reactions, migration paths, or other scenarios. As we saw with the Arctic Tern today in class (4/5/2021), the paths these birds take to vacation grounds can double in distance depending on weather events or priorities ... if a bird has time and doesn't want to get caught in an upcoming storm, it might flap on over to a nearby island (perhaps a little out of the way, adding mileage) in order to fuel back up and supply their relatively little bodies with the energy they need to complete their trip.

Bugs

A) https://imgur.com/a/BO0UIMD
B) https://imgur.com/a/KQRUAZS

Julkaistu huhtikuu 5, 2021 06:31 IP. käyttäjältä pyramidlakejake