Reproductive Ecology and Evolution

I started my walk at 8:35 A.M. in Warren NJ on April 21st ending my walk at 10:10 A.M. It was partly cloudy and 55 degrees F in a suburban neighborhood. Many birds were calling often especially that it was earlier in the morning and getting close to/ already breeding season. These calls/songs(mostly) particularly now can be related to territory defense, mate defense and mate attraction. Over the past three bird walks and just passing the same spots over the weeks it seems that there are a few birds that can regularly be found in the same area. Consistently in the same spot I have noticed one Eastern Bluebird flying over the same yard and sitting on the same power line that crosses over that lawn. This could very likely be the males territory that he is defending and by sitting on the power line over the more open part of the lawn he is better able to see and defend his territory. I am not sure whether or not it is a "quality" territory but it seems during this breeding season that this male is keen to protect it. Although I am not sure about the quality or exact size I can guess that it would be a relatively large area that the Eastern Bluebird can defend it easier which would attribute it to being a higher quality territory with more food. If the territory is also easily defendable this could be good for a potential nest the male can defend the nest from a distance which would decrease the risk of predation at the nest. Overall these attribute to a good quality territory and if it is in fact a quality territory this would mean that the bird is in good physical shape/condition to be able to keep this territory. Having a good territory would also help to attract a mate and increase the chance of his genetics being passed on.
A really common sight this time of year near me is to see a pairs of birds together, especially the House Finch. Often visiting the feeder you will see one male come up to the feeder and then immediately after the female shows up at the feeder. They fly away together and stay close. On today's walk one male and one female were sitting across the street and came over to a thorny bush together. The female flew back over the street and the male flew to the top of the bush. This could have been where they planned to nest or were already nesting as it would have provided good protection from bigger birds or animals. The bush was thick covered and had some thorns on some of the sticks which would help add some extra protection. Although this bush was near the open street and across from a large open lawn behind the bus and to the side of it there were big pine trees that provides some extra cover and could be a good place for the birds to fly into first before flying back to the nest which would help to lower the risk of predation. The female flew away and the male flowed right behind. This cold be an example of an over protective male that want to make sure that she doesn't go off and try to mat with other males for extra-pair bonds. During the breading season the pairs of birds stay close together and sometimes the females are followed by over protective males to prevent their mates from copulating with other males.
On a different day outside my friends house on the reef of a door was a robins nest with large clutch size of 6 blue eggs in a small open cup nest. Although the family rarely uses that door it still might not be the best spot to nest because it would be obvious of were the female is flying to. If prey was to be sitting on a tree at the edge of the lawn they would easily see the robin fly into her nest whereas in the dense forest the robin would not be as visible and could fly closer to the nest on one tree then more subtlety move into the nest in a short flight. Also by having such a large clutch size the mother would have to frequent the nest even further risking the chance of predation.
Mini activity: For the sound map I was able to hear birds from all around. It was a lot of different types of birds but the same individual birds calling repeatedly. There were a few birds that would call then another bird of the same species would call after. If these were songs it was most likely males completing for territory and/or females. One example of this that I heard was at least 2 different White-throated Sparrows singing in the distance. They have been often singing in this spot for the past 3 week and they are still here which may be usually since in central New Jersey they are really only supposed to be here for the non-breeding season and are supposed to move up to southern New York or only the very top of New Jersey (or even further north) for the breeding season. This may be a special localized case where White-throated Sparrows are staying further south year round because of climate change or maybe because they are able to be sustained in the are due to abundant resources that can support them during their nesting time. It is also a possibility that these locations change slightly over time and that books with range maps are not able to completely draw where each bird is but instead do a rough estimate of where they usually are during certain times.

(The picture of the area where i sat down are provided in the entry with the diagram of the sound map.)

Overall I saw Hermit Thrush(1), Eastern Bluebird(2), House Finch(3), Black-capped Chickadee(1), White-breasted Nuthatch(1), Turkey Vulture (1), Hawks(2)(maybe one Red-shouldered Hawk and one Sharp-shinned Hawk).

Publicado el abril 22, 2020 04:43 MAÑANA por carterl