Käyttäjän lenarose16 päiväkirja

Date - 4/4/21
Start time - 10am
End time - 11:30 am
Location - North St. and surrounding areas, Winooski
Weather (temperature, wind speed/direction, precipitation) - 52 degrees Fahrenheit, 13 mph wind, 60% cloud cover, no precipitation.
Habitat(s) - Residential/suburban area with sparse trees/little vegetation.

Year-round species I saw were Black-capped Chickadees, European Starlings, Ring-billed Gulls, Mourning Doves, Northern Cardinals, and American Crows. Foregoing migration may allow birds to avoid the risks inherent in migration (predation risk, etc.) while maintaining their own territories and also enabling them to capitalize on spring resources the moment they are available (VS. migrants, which must stake a new territory claim every season and may arrive after resources have begun to become available).

However, overwintering itself requires a number of adaptations to the cold, both behavioral and physiological/morphological, which can be costly - Black-capped Chickadees, as a case study, roost overnight in cavities to keep warm, have extra insulating down feathers, cache foods to save for later (something our overwintering corvids will also do), and have fairly generalist diets which may aid in their ability to survive in the low-resource environment. Species dependent on insects are absent from VT in the winter. Shivering, cross-current exchange and regulated hypothermia are other ways in which overwintering species cope with the cold.

The obligate migrants I saw were the Eastern Phoebe, Turkey Vulture, and Common Grackle. Common Grackles typically move further into the western and southern portions of their ranges in the U.S. during the winter, but some may stay in far southern VT, so they would be coming from no less than 100 miles away, but most likely further. Turkey Vultures in the northeast winter in the southern states usually, ~850 miles away. Eastern Phoebes migrate similar distances. That adds up to a very approximate distance of ~1,800 miles migrated total by these 3 species to get to Vermont. Arriving in early April before other migrants may allow these early migrants to stake out territory claims and get a headstart on breeding---but, as the last week or so has shown us, early spring can be very variable in terms of temperature and conditions, so it's a gamble, and enduring snowstorms may be especially challenging for some species not adapted to overwintering.

As for facultative migrants, until recently we had Pine Grosbeaks and other irruptive species in VT which had come due to low food availability in their typical, more northern ranges to eat shriveled fruits and seeds. These seem to have departed at this point, going back to their northern ranges as winter turns to spring and food becomes more available. I saw European Starlings, which I believe will either stay in their northern range here in VT year-round or migrate south to the middle states; the decision is probably based on food availability, the harshness of the winter, and maybe on dominance status, too. The environment can support fewer individuals over the winter due to lower food availability, so dominant individuals may stay while individuals in excess of the carrying capacity for that species in VT winter may be forced to migrate.

Date - 4/18/21
Start time - 5:30pm
End time - 7pm
Location - Trail leading to Lone Rock Point in Burlington, VT
Weather (temperature, wind speed/direction, precipitation) - 58 degrees Fahrenheit, 3 mph wind, 30% cloud cover, no precipitation.
Habitat(s) - trails through young mixed deciduous forest. Walked from the wooded area surrounding Rock Point school garden/buildings to the edge of Lake Champlain.

Date - 4/25/21
Start time - 9am
End time - 10:30am
Location - clearing around a cabin in Weld, Maine.
Weather (temperature, wind speed/direction, precipitation) - 48 degrees Fahrenheit, 0 mph wind, 60% cloud cover, 15% precipitation.
Habitat(s) - clearing surrounded by mixed deciduous/hardwood forest that has been regrowing from having been cleared for sheep pasture up until the 1930s. Remote location ~1 mile trail hike from a road.

Some of the behaviors related to the breeding season that I observed were singing, increased aggression, and gathering nest materials. I watched one Red-breasted Nuthatch carry a large piece of chicken down it found on the ground into a nearby maple tree, where it stashed the down in the crux of two branches, subsequently abandoning it (the down blew away in the wind). This individual seemed to be performing behaviors related to nesting but hadn't yet found a suitable nest cavity. I assume other birds' feathers and animal hair may play an important part then in nuthatches' (as well as other birds') nests; I later saw the remains of a Ruffed Grouse that had been plucked nearby (presumably by an owl), and thought those feathers might be a good source of nesting material.

Many birds were also singing, including Eastern Phoebes. Eastern Phoebes nest in the eaves of our home each year, and this pair had been seen the prior day scoping out several potential nest sites on the building. Eastern Phoebes are not cavity nesters like nuthatches, which allows them more flexibility in finding suitable nesting habitats. Eastern Phoebes nest in somewhat more open habitats than some of the other species I observed, which show a preference for denser, more coniferous forests--e.g. the Yellow-rumped Warbler, Evening Grosbeak, and Purple Finch. There was a marked difference between the birds I saw at the feeder and heard singing (i.e., staking out territorial claims) in the clearing vs. when I walked out into the woods--chickadees, jays, nuthatches, juncos, phoebes, and sparrows (Chipping and Song) dominated in the clearing, and in the denser woods I also heard Hermit Thrush, a Winter Wren, a Blue-headed Vireo, and I flushed a Ruffed Grouse. This likely reflects different nesting habitat preferences for open vs. dense habitats and deciduous vs. coniferous.

Some of these birds were just arriving and staking out territory claims. Given how early they are, I would presume that the Winter Wren, Hermit Thrush, and Blue-headed Vireo that I already heard singing this early in the season were able to stake out high-quality territories before others got to them first. These birds may be more fit, e.g. if individuals that are in better physical condition are more likely to arrive on the breeding grounds early. Maybe they were able to fly faster during migration or leave earlier due to building up sufficient fat stores more quickly.

I found the mini-activity extremely hard! Surely there must be some standard way of notating bird songs by hand... Mine was a mess, but I'd like to learn because there have been times I heard a song in the field and didn't have my phone to record it but wanted to look it up later.