Archivos de diario de mayo 2020

08 de mayo de 2020

Calvert County Damselflies & Dragonflies: Part 18 – Bluet Damselflies of the Family Coenagrionidae

Family: Coenagrionidae (Bluets)

This is the third and final family of damselflies to be examined in this series of posts. Due to the large number of species present for the Coenagrionidae damselfly family, I have been breaking down this particular family into smaller segments. This grouping is comprised entirely of the genus Enallagma, the Bluets.

In Richard Orr’s Maryland database, there are eleven species of Bluet damselfly species listed as present in at least one of the three southern Maryland counties. Seven of those species are present in all three counties. All eleven species have been reported in Charles County with nine and seven species reported for St. Marys and Calvert Counties, respectively. Five of the eleven species are on the S3 Watch List.

The iNaturalist observation database for all damselflies in the southern Maryland counties is quite sparse and once again the same pattern continues with this group. There are only 10 research grade observations in total for the three counties and five of that total were submitted by me, all in Calvert County (Big Bluet x 4, Familiar Bluet x 1). They are the only Calvert County observations. St. Marys County has a single observation for each of two species (Big Bluet and Familiar Bluet), and Charles County has three observations total for two species (Big Bluet x 2, Orange Bluet).

Listed below are the species within this group that have been observed in at least one of the southern Maryland counties and a comparison of the two databases is made (as of March, 2020). As was done with the previous family, I have included notes extracted from the book “Natural History of DelMarVa Dragonflies and Damselflies” by Hal White (reference 1). Of particular relevance for Calvert County, I have also included information on the six species that were observed at the Cove Point LNG Property and reported in “2011-2012 Survey of the Dragonflies and Damseflies (Odonata) of the Cove Point LNG Property (Calvert County, Maryland” by Richard Orr (reference 2).

Azure Bluet/Enallagma aspersum
Damselflies and dragonflies have large compound eyes that dominate the head. They also have three small, simple eyes that lie near the top and middle of the head. The extra eyes are called ocelli and are believed to provide close-up vision. (1)
Cove Point adult abundance and flight period – common/05-May to 11-Sept. (2)
iNaturalist research grade observations:​ Calvert = 0​ St. Marys = 0 Charles = 0
MD Biodiversity (i.e., Richard Orr):​ Calvert – present St. Marys – present ​ Charles - present

Double-striped Bluet/Enallagma basidens
The Double-striped Bluet represents one of the most dramatic range expansions in the US. Prior to 1930, it was unknown north and east of Texas. In just over 50 years it has expanded its range to the eastern US and as far north as New York. (1)
Cove Point adult abundance and flight period – uncommon/05-Jun to 11-Sept. (2)
iNaturalist research grade observations:​ Calvert = 0 St. Marys = 0 Charles = 0
MD Biodiversity (i.e., Richard Orr):​ Calvert – present St. Marys – present Charles - present

Familiar Bluet/Enallagma civile
Familiar Bluets feed away from water and hover over plants to pluck insects from leaves instead of catching them in flight. (1)
Cove Point adult abundance and flight period – abundant/04-May to 02-Dec. (2)
iNaturalist research grade observations:​ Calvert = 1 (Oct) St. Marys = 1 (Sept)​ Charles = 0
MD Biodiversity (i.e., Richard Orr):​ Calvert – present St. Marys – present Charles - present

Attenuated Bluet/Enallagma daecki
S3 Watch List (see below for definition)
In the late 1800’s, damselflies were considered as a subgroup among dragonflies rather than the separate group equal to dragonflies as currently cataloged. (1)
iNaturalist research grade observations:​ Calvert = 0 St. Marys = 0 Charles = 0
MD Biodiversity (i.e., Richard Orr):​ Calvert – X St. Marys – present Charles - present

Turquoise Bluet/Enallagma divagans
S3 Watch List (see below for definition)
Adults can survive under water when ovipositing. Presumably the hairs on their thorax help to create a bubble of air that enables them to breathe underwater. (1)
Cove Point adult abundance and flight period – rare/16-Jun. (2)
iNaturalist research grade observations:​ Calvert = 0 St. Marys = 0 Charles = 0
MD Biodiversity (i.e., Richard Orr): ​Calvert – present St. Marys – present Charles – present

Big Bluet/Enallagma durum
S3 Watch List (see below for definition)
The Big Bluet is known for its salt tolerance and is common in freshwater estuaries along the northeastern Atlantic Coast. (1)
iNaturalist research grade observations:​ Calvert = 4 (Jul-Aug) St. Marys = 1 (Jun) Charles = 2 (Jun-Aug))
MD Biodiversity (i.e., Richard Orr):​ Calvert – present St. Marys – present​ Charles - present

Stream Bluet/Enallagma exsulans
The Stream Bluet is a delicate damselfly that prefers Piedmont streams, while most of its bluet relatives prefer ponds. (1)
iNaturalist research grade observations:​ Calvert = 0 St. Marys = 0 Charles = 0
MD Biodiversity (i.e., Richard Orr):​ Calvert – X St. Marys – X​ Charles - present

Skimmming Bluet/Enallagma geminatum
Studies of mitochondrial DNA from bluets indicate that the many species of bluets found in DelMarVa represent a recently evolving species swarm (a group of closely-related species), recently meaning the last period of glaciation. (1)
Cove Point adult abundance and flight period – rare/04-Jun. (2)
iNaturalist research grade observations:​ Calvert = 0 St. Marys = 0 Charles = 0
MD Biodiversity (i.e., Richard Orr):​ Calvert – present St. Marys – present​ Charles - present

Orange Bluet/Enallagma signatum
Damselflies are often observed flying in tandem even after mating which assures that no other male can mate with the female. (1)
Cove Point adult abundance and flight period – common/03-Sept to 14-Oct. (2)
iNaturalist research grade observations:​ Calvert = 0 St. Marys = 0 Charles = 1 (Sept)
MD Biodiversity (i.e., Richard Orr):​ Calvert – present St. Marys – present​ Charles - present

Slender Bluet/Enallagma traviatum
S3 Watch List (see below for definition)
Look for Slender Bluets in June and July in the vegetation along the shores of ponds. (1)
iNaturalist research grade observations:​ Calvert = 0 St. Marys = 0 Charles = 0
MD Biodiversity (i.e., Richard Orr):​ Calvert – X St. Marys – present Charles - present

Vesper Bluet/Enallagma vesperum
S3 Watch List (see below for definition)
Approximately 90% of dragonfly and damselfly species found in DelMarVa had been described by 1919, the year that the Vesper Bluet was first described. (1)
iNaturalist research grade observations:​ Calvert = 0 St. Marys = 0 Charles = 0
MD Biodiversity (i.e., Richard Orr):​ Calvert – X St. Marys – X​ Charles - present

Definitions from the Maryland Department of Natural Resources “List of Rare, Threatened, and Endangered Animals of Maryland”:
S3 - Vulnerable / Watchlist — At moderate risk of extinction or extirpation due to a fairly restricted range, relatively few populations or occurrences, recent and widespread declines, threats, or other factors. Typically occurring in 21-80 populations.

Ingresado el 08 de mayo de 2020 por rosalie-rick rosalie-rick | 0 comentarios | Deja un comentario

26 de mayo de 2020

Calvert County Damselflies & Dragonflies: Part 19 – Forktail/Sprite Damselflies of the Family Coenagrionidae Family: Coenagrionidae (Forktails/Sprites)

Family: Coenagrionidae (Forktails/Sprites)

This is the third and final family of damselflies to be examined in this series of posts. Due to the large number of species present for the Coenagrionidae damselfly family, I have been breaking down this particular family into smaller segments. This is the final grouping within this family and this will also conclude the review of the various Odonata families found in Calvert County and the surrounding counties of Charles and St. Marys.

In Richard Orr’s Maryland database, there are five species of Forktail damselfly species listed as present in at least one of the three southern Maryland counties and two species of Sprites. Four of the seven species are present in all three counties. Six of the seven species have been reported in Charles County with four and five species reported for St. Marys and Calvert Counties, respectively. One of the Forktail species is on the S3 Watch List and both of the Sprite species are on the S1 or S2 list.

Unlike the the iNaturalist observation database for most damselflies in the southern Maryland counties that is very sparse, the number of observations for this group is significantly greater (as of May, 2020). This has been in large part skewed by my own abundant observations of Rambur’s Forktails. Currently there are not any observations for two of the Forktail species and none for the two Sprite species. St. Marys County has a total of four observations for two species (Rambur’s x 3, Fragile x 1), and Charles County also has four observations but for a single species (Eastern). Calvert County is discussed below.

During the summer of 2019, I developed a fascination for Rambur’s Forktails. They were the first species of damselfly that I had ever bothered to examine closely. This was due in large part because they could easily be observed in my own yard. A portion of my yard is in contact with a brackish body of water (Lake Charming) and once I discovered the existence of this particular species, I could observe them on a daily basis. I was rewarded with my first views of damselfly mating behavior, but also confronted with the challenge of trying to photograph such a small insect. Of the 25 Calvert County Rambur’s Forktails observations in the iNaturalist database, 21 are mine. My observations in 2019 started on 24 June and they were last observed in mid-October. In 2020 my first observation of a Rambur’s Forktail in the yard area was on May 8th, the day before a frost warning struck the area. The identification has not been confirmed (i.e., not research grade). No other individuals were sighted until yesterday (May 25th). A male and a female were observed, but I was only able to capture the female photographically. The second forktail damselfly recorded for Calvert County is the Fragile Forktail. Four of the seven observations were recorded recently (spring, 2020) including two from me.

Listed below are the species within this group that have been observed in at least one of the southern Maryland counties and a comparison of the two databases is made (as of May, 2020). As was done with the previous family, I have included notes extracted from the book “Natural History of DelMarVa Dragonflies and Damselflies” by Hal White (reference 1). Of particular relevance for Calvert County, I have also included information on the four species that were observed at the Cove Point LNG Property and reported in “2011-2012 Survey of the Dragonflies and Damseflies (Odonata) of the Cove Point LNG Property (Calvert County, Maryland” by Richard Orr (reference 2).

Citrine Forktail/Ischnura hastata
In the Azores, researchers discovered a population of Citrine Forktails that were able to produce fertile eggs in the absence of males. This is the only documented case of parthenogenesis in damselflies or dragonflies. (1)
Cove Point adult abundance and flight period – uncommon/21-Apr to 30-Sept. (2)
iNaturalist research grade observations:​ Calvert = 0​ St. Marys = 0 Charles = 0
MD Biodiversity (i.e., Richard Orr):​ Calvert – present St. Marys – present ​Charles - present

Lilypad Forktail/Ischnura kellicotti
S3 Watch List (see below for definition)
Many species of damselflies and dragonflies exhibit sexual dimorphism (male and female look different). In the case of Lilypad Forktails, the females also exhibit polychromism and can be found in three different color forms. (1)
iNaturalist research grade observations:​ Calvert = 0 St. Marys = 0 Charles = 0
MD Biodiversity (i.e., Richard Orr):​ Calvert – X St. Marys – X Charles - present

Fragile Forktail/Ischnura posita
Fragile Forktails are our most common and widespread damselfly. They have a wide habitat tolerance and can be found at nearly every pond, marsh, or slow-moving stream. (1)
Cove Point adult abundance and flight period – abundant/01-Apr to 30-Sept. (2)
iNaturalist research grade observations:​ Calvert = 7 (Mar-May) St. Marys = 1 (Jul) Charles = 0
MD Biodiversity (i.e., Richard Orr):​ Calvert – present St. Marys – present Charles - present

Rambur’s Forktail/Ischnura ramburii
Damselflies identification is often based on the species-specific shape of the appendages at the tip of the abdomen which the male uses to grasp the female during mating. (1)
Cove Point adult abundance and flight period – abundant/21-Apr to 14-Oct. (2)
iNaturalist research grade observations:​ Calvert = 24 (May-Oct) St. Marys = 3 (Jun-Sept) Charles = 0
MD Biodiversity (i.e., Richard Orr):​ Calvert – present St. Marys – present Charles - present

Eastern Forktail/Ischnura verticalis
Female Eastern Forktails mate only once and carry up to 2,000 eggs. (1)
Cove Point adult abundance and flight period – common/21-Apr to 30-Sept. (2)
iNaturalist research grade observations:​ Calvert = 0 St. Marys = 0 Charles = 4 (Apr-Sept)
MD Biodiversity (i.e., Richard Orr):​ Calvert – present St. Marys – present Charles – present

Sphagnum Sprite/Nehalennia gracilis
S2 Watch List (see below for definition)
The Sphagnum Sprite, as its name implies, lives in sphagnum-choked bogs and fens. (1)
iNaturalist research grade observations:​ Calvert = 0 St. Marys = 0 Charles = 0
MD Biodiversity (i.e., Richard Orr):​ Calvert – X St. Marys – X Charles - present

Southern Sprite/Nehalennia integricollis
S1/S2 Watch List (see below for definition)
The Southern Sprite is one of our smallest damselflies. It is easly overlooked because it is inconspicuous and rarely flies unless disturbed. (1)
iNaturalist research grade observations:​ Calvert = 0 St. Marys = 0 Charles = 0
MD Biodiversity (i.e., Richard Orr):​ Calvert – present St. Marys – X Charles - X

Definitions from the Maryland Department of Natural Resources “List of Rare, Threatened, and Endangered Animals of Maryland”:
S1 - Critically Imperiled / Highly State Rare — At very high risk of extinction or extirpation due to very restricted range, very few populations or occurrences, very steep declines, very severe threats, or other factors. Typically occurring in five or fewer populations.

S2 - Imperiled / State Rare — At high risk of extinction or extirpation due to restricted range, few populations or occurrences, steep declines, severe threats, or other factors. Typically occurring in 6-20 populations.

S3 - Vulnerable / Watchlist — At moderate risk of extinction or extirpation due to a fairly restricted range, relatively few populations or occurrences, recent and widespread declines, threats, or other factors. Typically occurring in 21-80 populations.

Ingresado el 26 de mayo de 2020 por rosalie-rick rosalie-rick | 0 comentarios | Deja un comentario