The Purple Finch is a small North American songbird known for its colorful plumage. Males have bright reddish-purple heads and breasts, while females are more brownish in color. Purple Finches build nests in trees and lay pale blue or greenish eggs with brown speckles.
Nesting Behavior
Purple Finches begin breeding in late spring and early summer. The female builds a nest out of grasses, plant fibers, moss, and animal hair, lining it with softer materials like feathers. She constructs the nest in the fork of a tree branch, well-hidden among dense leaves and needles.
Nests are usually built 10-40 feet off the ground. Purple Finches often reuse the same nest or build a new one right on top of an old nest from the previous year. They may also occasionally take over an abandoned songbird nest. Females carry most of the nest-building duties, but the male may help gather some material.
Egg Laying
Once the nest is complete, the female lays a clutch of 4-5 eggs. She produces one egg per day in the early morning. Purple Finch eggs are oval in shape with a pale blue or greenish background color speckled with brown spots. The spots help camouflage the eggs when the female is away from the nest.
The eggs measure about 0.75 inches long and 0.5 inches wide. The female incubates the eggs for 12-14 days before they hatch. She develops a brood patch, which is a bare area of skin on her belly used to transfer warmth to the eggs. The male may visit the nest occasionally, but does not participate in incubation.
Hatching
Purple Finch hatchlings are altricial, meaning they are born naked, blind, and helpless. Their eyes remain closed for several days as they are brooded in the nest. The chicks are fed regurgitated insects and seeds by both parents. They grow quickly, opening their eyes at around 6 days old and developing juvenile plumage by 2 weeks.
The nestlings fledge (leave the nest) after about 12-17 days, when they can hop from branch to branch. The parents continue caring for the fledglings for another couple weeks, teaching them to find food and evade predators. Purple Finches typically raise one brood per breeding season.
Egg Description
Here are some key facts about Purple Finch egg size, color, and appearance:
- Size: 0.75 x 0.5 inches
- Shape: Oval
- Color: Pale blue or greenish white background with brown speckles
- Number: 4-5 per clutch
- Surface: Glossy, smooth
The background color varies slightly, from a greenish-white or pale blue to a very light tan. The speckles are small and reddish-brown to brown in color. They are concentrated more on the broad end of the egg. The eggs have a smooth, slightly glossy surface and oval shape with one end that is more pointed than the other.
Color Variation
There can be some variation in the intensity and exact hue of the background color from egg to egg. Some Purple Finch eggs appear whiter while others are more green-tinted or blue-tinted. The amount of speckling also varies, with some eggs being very densely mottled while others have sparser speckling.
These differences are due to genetic factors as well as environmental conditions and diet that affect the female’s physiology during egg formation. The egg color often matches the environment where it was laid as camouflage. For example, eggs may be more blue-green in coniferous areas and more tan or buff-colored in deciduous trees.
Egg Strength
Songbird eggs like those of the Purple Finch have evolved to be lightweight but very strong and durable. The eggshell is made of calcium carbonate and protects the developing chick inside. It has a smooth, pore-free surface that helps prevent bacterial contamination.
Yet, the shell is thin enough to allow air exchange for respiration. The oval shape also gives strength against cracking compared to spherical eggs. The female develops a bare brood patch to transfer heat to the eggs without crushing them.
Comparison to other Songbirds
Purple Finch eggs share many traits with related songbirds in the finch family. Below is a comparison of Purple Finch egg characteristics to other finches:
| Species | Background Color | Spot Color | Clutch Size |
|---|---|---|---|
| Purple Finch | Pale blue/green | Brown | 4-5 eggs |
| House Finch | Pale blue | Brown | 4-6 eggs |
| American Goldfinch | Pale blue | Reddish-brown | 4-6 eggs |
| Cassin’s Finch | Pale blue | Brown | 4-5 eggs |
As you can see, the colors and markings are very similar across finch species. However, Purple Finch clutches tend to be slightly smaller than other finches. Their eggs can be distinguished from other species by the more greenish or blue-green background tint.
Role in Identification
The appearance of the eggs can provide helpful clues in identifying Purple Finch nests, especially when the parents are away. Characteristics like the egg color, spots, size, and shape should be compared to other potential nesting species in the area.
Location may also help ID the nest, as Purple Finches choose specific nesting sites in trees. Identifying egg features along with behavior of the parents at the nest will confirm whether it belongs to a Purple Finch.
Field Marks
Here are the key Purple Finch egg features to look for:
- Background color: pale greenish-blue or greenish-white
- Spots: small, brown, concentrated on broad end
- Size: 0.75 x 0.5 inches
- Shape: Oval
- Number: 4-5
- Nest: cup in tree fork, 10-40 feet up
These field marks distinguish Purple Finch eggs from other songbirds. The nest site provides additional context on the identity. Combining these clues will allow positive identification.
Diagnostic Features
The greenish cast to the background color is the most diagnostic feature of Purple Finch eggs compared to other finches. The small brown speckling pattern is also unique.
House Finch eggs appear very similar, but lack the green tint. Cassin’s Finch eggs show more defined brown speckling. The nest location in trees helps differentiate from ground-nesting finches.
Conservation Status
Purple Finches have a large breeding range across northern North America. Partners in Flight estimates a global breeding population of 22 million with about 62% spending part of the year in the U.S. They are still common and their population appears to be increasing.
Purple Finches and their eggs face threats from habitat loss and predation, but not at levels that significantly impact their numbers. As a result, the IUCN Red List classifies the Purple Finch as a species of Least Concern.
However, Breeding Bird Survey data does show a small decline of about 1% per year in Purple Finch populations in the eastern United States since the 1960s. The reasons are unclear but could be linked to diseases at bird feeders. Overall the species remains common across its range.
Conclusion
The eggs of Purple Finches are pale blue-green with brown speckling. This coloration helps camouflage the eggs in the nest when the parents are away. The eggs measure about 0.75 x 0.5 inches and are laid in clutches of 4-5 per nest. The greenish background hue helps distinguish Purple Finch eggs from other finch species.
Identifying the eggs can aid in confirming the owners of a songbird nest along with behavior of the adults. Purple Finch populations are declining in some areas but the species remains common throughout its range. Protecting nesting habitat will help ensure healthy populations in the future.
