Visually Sexing Loggerhead Shrike (Lanius Ludovicianus) Using Plumage Coloration and Pattern

Loggerhead shrike has lost more than 50%of the population across North America over the past 40 years. The ability to determine sex in loggerhead shrike has given us another tool to help understand what is causing the decline and how conservation breeding can best help offset the threats. The plumage of loggerhead shrike is sexually monomorphic so birds can not be reliably sexed in hand, using physical characteristics as in the case for many other species.

DNA sexing is possible but is expensive, time delayed and requires special equipment. Our simple method is easy and quickly undertaken, with results indicating a high accuracy rate, that increases with a small amount of training. Shrike's can be sexed, in hand, by examining the sixth primary wing feather.

However, the pattern varies amongst individuals. The most difficult part of our method is deciding how far the brown in the rachis extends through the white and only going on to additional steps if the sex cannot be determined based on this characteristic alone. We suggest that anyone who hasn't used this method before, review the video and become familiar with the characteristics they are looking at, as well as the order in which to assess them.

Feel free to contact us and we can provide sample photos used in our citizen science survey. Begin by firmly holding the bird using the banders grip and carefully extending one wing to allow the sixth primary feather to be viewed, making sure to not overextend the wing. Locate the P6 feather by counting forward from the first primary.

Assess the brown in the rachis and determine if it extends at least halfway through the white and touches the distal end of the primary covert feathers. If it does, the bird is female. If unsure of the sex, based on the color of the rachis, assess the symmetry of the brown to white transition on each side of the shaft.

If the brown meets at the same spot on either side of the shaft, the bird is male. If the line meets asymmetrically at the shaft, creating a step or notch, the bird is a female. If there is still uncertainty, examine the angle of the transition between the brown and the white coloration.

If the brown has a steep angle where it meets the white, forming an upside down V, the bird is a female. If the pattern looks more like an M, the bird is male. This sexing protocol was tested on 120 participants, who read a brief instruction on how to sex using feather patterns and then attempted to sex a series of 26 shrikes based on a photograph.

Most participants ranked themselves as having little or no experience with birds. The participants averaged a 77%correct assessment for both females and males. Ten volunteers received in person training on this method and attempted to sex the same series of 26 photos which they had not seen before.

The individuals trained one on one, correctly assessed 12 out of 13 photos of females and 11 out of 13 photos of males. When attempting this method, the most critical step is determining how far the brown in the rachis extends through the white, only if there is question about whether or not the brown touches the primary coverts, should the observer continue on to assess other characteristics. Out method of sexing shrike in hand, can be done when handling wild shrike's during banding, and included with other data collection like age and wing cord length.

For captive birds, sexing can coincide with the need to handle birds for vaccination, banding or other routine management. To date, more than 1000 young birds have been released into the wilds of Ontario. A rapid and inexpensive method for sexing young birds makes it possible to quantify how many birds of each sex are released and if sex biased mortality is occurring.