Crow Patrol: Dec 2018 Pellet Analysis

Crow Patrol: Dec 2018 Pellet Analysis

In early December 2018, the truck depot parking lot along South Canal St. in Lawrence, MA provided ample opportunity to collect ejected pellets from the wintering American and Fish Crows. Each morning, the Crows left behind cast pellets from the night before. From Birds of North America, we learn that Crows casts pellets throughout the day and overnight in the roosts; pellets contain indigestible, sclerotized parts of insects, chaff, pits, bones, and eggshells. Pellets are likely regurgitated after arrival at roost, perhaps within 2 hours. Typically plant material makes up much (69%) of the Crow diet, consistent with other studies. During the colder winter months, this is likely a much higher percentage.  The recently completed initial Crow pellet analysis performed by Tom French in 2019 offered up a number of fascinating highlights:

  • Preliminary report on the contents of the first 108 crow pellets collected in Lawrence, Essex Co., MA by Craig Gibson on December 6, 2018 (89 pellets), and December 10, 2018 (19 pellets).
  • In 2018, most pellets were stored separately and analyzed individually.
  • In 2017, about 95% by volume and 90-95% by frequency of the material contained in the pellets was from Asian Bittersweet (Celastrus orbiculatus) berries.
  • In 2018, bittersweet was again an important food item, but was far less dominant.

Here is Tom’s preliminary report:

This is a preliminary report on the contents of the first 108 crow pellets collected in Lawrence, Essex Co., MA by Craig Gibson on December 6, 2018 (89 pellets), and December 10, 2018 (19 pellets). More will be examined later. In December 2017, about 130 pellets were collected, but were not kept separately and most disintegrated so they could not be examined individually. In 2018, most were kept separately and were analyzed individually. In 2017, about 95% by volume and 90-95% by frequency of the material contained in the pellets was from Asian Bittersweet (Celastrus orbiculatus) berries. The pellets containing bittersweet were easily identified by their rich orange color.

In 2018, bittersweet was again an important food item, but was far less dominant. Many of the pellets contained unidentifiable plant fibers, skin, pulp, etc. Some of these pellets probably contained pumpkin pulp with no seeds to confirm an identification. The primary food and non-food items identified in the 2018 crow pellets are listed below with the number of pellets out of the total 108 in which the item was identified (and the percent frequency in brackets):

Seeds

An unknown seed (possibly Staghorn Sumac) – 49 (45%)

Asian Bittersweet seeds – 38 (35%)

Pumpkin – 16 (15%)

Buckthorn – 11 (10%)

Unknown small flat pea-shaped seed – 11 (10%)

Acorn – 10 (9%)

Large seed “meat” (acorn or other large seed) – 8 (7%)

Poison Ivy – 7 (6%)

Corn – 4 (3.7%)

Cantaloupe – 4 (3.7%)

Rubus sp. (blackberry/raspberry) – 3 (2.7%)

Safflower – 2 (1.9%)

Four other species of unidentified seeds from 1, 1, and 2 pellets each

Vertebrate animals

Bone fragments from squirrel/rabbit-size mammal – 26 (24%)

Mouse – 7 (6%) (1 Peromyscus leucopus, 2 Microtus pennsylvanicus, 4

Peromyscus/Microtus (possible prey or scavenged)

Larger rodent, probably rat – 2 (1.9%) (possible prey or scavenged)

Short-tailed Shrew (Blarina brevicauda) – 1 (0.9%) (possible prey or scavenged)

Muskrat fur – 1 (0.9%) (scavenged)

Raccoon/opossum (1 tail vertebra) – 1 (0.9%) (scavenged)

Small snake – 1 (0.9%) (possible prey or scavenged)

Bird (possible pigeon vertebrae) – 1 (0.9%) (probably scavenged)

Chicken (discarded human trash) – 3 (2.7%)

Chicken egg shell fragments – 8 (7%)

Invertebrates

Insect parts – 3 (2.7%)

Saltmarsh Snail, Melampus bidentatus – 3 (2.7%) (with 1, 1, and 26 each)

Crab shell fragments? – 6 (5.5%)

Non-food items picked up while feeding

Small stones (about 3-10 mm long) found in 104 of the 108 pellets (96%), and numbering up to 91 (average 30) per pellet

The following list of small foreign objects suggests that many of the crows were feeding in an old industrial area consistent with the abandoned parking areas associated with the old mill buildings where the crows have been seen staging, and possibly in the vicinity of where the pellets were collected.

Glass – 23 pellets (21%) with the number of pellets containing the following colors of small glass fragments. It was common to have 4 colors in a single pellet.

Clear – 16 (15%)

Light green – 13 (12%)

Dark green – 9 (8%)

Brown – 9 (8%)

Blue – 1 (0.9%)

Coal slag – 7 (6%)

Charcoal – 7 (6%)

Hard plastic – 5 (4.6%)

Aluminum foil – 4 (3.7%)

Asphalt – 4 (3.7%)

Plastic film/bag – 4 (3.7%)

Lead solder – 2 (1.9%)

Concrete – 2 (1.9%)

Red brick fragments – 2 (1.9%)

Plastic packing beads – 2 (1.9%)

Metal shaving – 1 (0.9%)

Silicone seal rubber – 1 (0.9%)

A paper staple – 1 (0.9%)

These foods suggest feeding in the following situations:

  1. In and along the edges of abandoned industrial parking lots with Asian bittersweet, sumac, poison ivy, asphalt, concrete, broken glass, lead solder, etc.
  2. Scavenging for squirrel/rabbit size mammals, and possibly smaller animals dead on the road.
  3. Possibly preying on white-footed mice, meadow voles, a short-tailed shrew, and a small snake, and insects.
  4. Possibly in agricultural fields with pumpkins and corn, but probably more likely around human refuse with pumpkins, cantaloupe, corn, and discarded chicken parts.
  5. Possibly feeding occasionally around a house with a bird feeder where a small number of safflower seeds were eaten in both 2017 and 2018, and one sunflower seed was eaten in 2017.
  6. Feeding in a saltmarsh (in both years) which is the only source of saltmarsh snails.
2019-06-04T07:59:06+00:00 June 2nd, 2019|0 Comments

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