Field Notes Journal

Seasonal Analysis and Species Classification

Rosebay Willowherb

Model Family : Seasonal presence

Rosebay Willowherb (Chamaenerion angustifolium)
Rosebay Willowherb (Chamaenerion angustifolium) David Walker, Field Notes Journal ( CC BY 4.0 )
View of Chapelfield with Rosebay Willowherb (Chamaenerion angustifolium) in the foreground
View of Chapelfield with Rosebay Willowherb (Chamaenerion angustifolium) in the foreground David Walker, Field Notes Journal ( CC BY 4.0 )

Summary

Rosebay Willowherb

Moderate autumn seasonal presence

Rosebay Willowherb is classified as moderate autumn seasonal presence. The fitted seasonal window runs from about June to September, with a autumn peak around September. The season is moderate, with a sharp active window, strong post-peak decline, and strong off-season suppression.

Confidence
Medium
Peak
September
Season
June–September

Seasonal wheel

Seasonal wheel for Rosebay Willowherb Rosebay Willowherb Peak: September

Calendar strip

Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Highlighted months indicate stronger modelled presence or detectability. A ring marks the fitted peak; a hollow mark indicates the trough where available.

Classification evidence

Season start month
6.175
Season end month
9.295
Forcing peak month
8.615
Season width months
3.12
Season midpoint month
7.735
Season start label
June
Season end label
September
Forcing peak label
September

Observed and Simulated Seasonal Patterns

Rosebay Willowherb Observed Presence, Abingdon
Rosebay Willowherb Observed Presence, Abingdon
Rosebay Willowherb Observed Totals, Abingdon
Rosebay Willowherb Observed Totals, Abingdon
Rosebay Willowherb Simulated Presence, Abingdon
Rosebay Willowherb Simulated Presence, Abingdon

Cite this dataset

You are welcome to reuse or reproduce this material under the terms of the Creative Commons CC BY 4.0 licence but please cite it using the reference below, include a link to the licence, and indicate if any changes were made.

Walker, David. Rosebay Willowherb. Field Notes Journal. ID FN-WL-SEASONAL. Version 2026.05.21. https://fieldnotesjournal.uk/wildlife/seasonal/abingdon/rosebay_willowherb.html

Dataset FN-WL-SEASONAL Author David Walker Publisher Field Notes Journal Version 2026.05.21
Reference: Walker, David. Rosebay Willowherb. Field Notes Journal. ID FN-WL-SEASONAL. Version 2026.05.21.

BibTeX 
@dataset{fn_wl_seasonal,
  author = {Walker, David},
  title = {Rosebay Willowherb},
  year = {2026},
  publisher = {Field Notes Journal},
  version = {2026.05.21},
  url = {https://fieldnotesjournal.uk/wildlife/seasonal/abingdon/rosebay_willowherb.html}
}